CHAPTER VIII
New Hebrides, Solomon Islands, Saint Matthias Group, and Ryukyu Islands
Paul A. Harper, M.D.,Wilbur C. Downs, M.D., Paul W. Oman, Ph. D., and Norman D. Levine, Ph. D.
A review of the experienceswith malaria control of the USAFISPA (U.S. Army Forces in the South PacificArea) may logically be divided into two parts: The first, dealing with theproblem of malaria and other insect-borne diseases on those South Sea Islandswhich lay within the jurisdiction of the wartime command known as the SouthPacific Area; the second, dealing with similar problems on Okinawa and otherislands which were the responsibility of the Ryukyu Islands Command. 1
The military campaigns in both these areas were a series of amphibious operations which called forthe closest cooperation between land, sea, and air forces. The antimalaria organization in both areas was also a joint Army, Navy, and Allied operation under centralized control. This report is concerned primarily with the malariacontrol activities of Army personnel, but it is emphasized that much of thesuccess of the organization was due to its joint service nature which wasthe concept of the first theater malaria and epidemic disease control officerin the South Pacific, Comdr. (later Capt.) James J. Sapero, MC, USN, 2 and of his successor, Comd. F. A. Butler, MC, USN. 3
1 Unless otherwise indicated, Part I of this chapter is based on the material from a series of papers published in a supplement to the American Journal ofTropical Medicine, May 1947, on "Malaria and Other Insect-Borne Diseasesin the South Pacific Campaign, 1942-1945." Appreciation is expressed to theeditor and publisher of this journal for permission to utilize this material.
Appreciationis also expressed to Brig. Gen. Earl Maxwell, U.S. Army, Surgeon, U.S. ArmyForces in South Pacific Areas, and subsequently Surgeon, Ryukyu Islands command:to Capt. Arthur H. Dearing, MC, USN, Force Medical Officer, South PacificArea; to his successor, Capt. Frederick R. Hook, USN; and to Brig. J. W.Twhigg, Director of Medical Services, New Zealand Expeditionary Forces, Pacific.These officers gave their constant support to the Malaria and Epidemic ControlOrganization and its work as described in this chapter.
2 (1) Sapero, J. J., and Butler, F. A.: Highlights on Epidemic Diseases Occurring in MilitaryForces in the Early Phases of the War in the South Pacific. J.A.M.A. 127:502-506, March 1945. (2)Sapero, J. J.: The Malaria Problem Today; Influenceof Wartime Experience and Research. J.A.M.A.. 132: 623-627, November 1946.(3) Sapero, J. J. : Tropical Diseases in Veterans of World War II. New EnglandJ. Med. 235: 843-846, December 1946. (4) Sapero, J. J.: Tropical Diseasesas a Cause of Manpower Loss in Military Operations. Mil. Surgeon 106 : 111-114,February 1950. (5) Sapero, J. J. : Prevention of Malaria Infections by DrugProphylaxis. In Malariology, edited by Mark F. Boyd. Vol. II,pp. 1114-1132. Philadelphia: W. B. Saunders Co., 1949.
3 (1) Butler, F. A.: Malaria Control Program on a South Pacific Base, U.S. Nav. M. Bull. 41: 1603-1612, November 1943. (2) Butler, F. A., and Sapero, J. J.: Postwar Tropical Disease Problems in the United States. South. Med. J. 38: 459-465, July 1945. (3) Butler, F. A., and Sapero, J. J.: Pacific Vivax Malaria inthe American Negro. Am. J. Trop. Med. 27: 111-115, March 1947.
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Subsequently, CaptainSapero occupied a similar position on the staff of Commander in Chief, Pacific,during the campaign for the Ryukyu Islands.
The reason for havingone group of authors report about malaria control in such widely separatedplaces is that members of this group, together with their Navy colleagues,participated in the planning and execution of insect control programs inboth areas, first in the South Pacific and later on in the Ryukyu Islands,which was the scene of the last severe land fighting of the war.
Part I. New Hebrides, Solomon Islands, and Saint Matthias Group
GENERAL CONSIDERATIONS
Malaria problem, 1942-45. - Malaria was the single most serious health hazard to Allied troops in the South Pacific Area during World War II; it caused more than five times as many casualties as did combat. It is estimated that more than100,000 individuals among Allied military personnel contracted malaria inthe South Pacific, most of whom had several attacks. At least, on Guadalcanal, Solomon Islands, this disease threatened the success of the military campaign.
The first outbreak of malaria occurred on the small island of Efate in the New Hebrides, where it reached epidemic proportions with a rate of nearly 2,700 cases per 1,000 troops per annum in April 1942. The most serious epidemic of this disease began on Guadalcanal within 3 months of the initial landings. Lesser outbreaks occurred on Espíritu Santo, Tulagi-Florida Islands, the Russell Islands,and Munda, New Georgia. No serious outbreaks occurred on Treasury, Bougainville,Green, or Emirau Islands, which were the last four bases to be occupied andwhich were the scene of intense anti-malaria measures from the time of theinitial landings.
In the early days of the South Pacific campaign, it was considered good medical practice togive therapeutic doses of Atabrine (quinacrine hydrochloride) or quinine toheavily seeded troops after removal from malarious areas and then to stopsuppressive medication and treat the remaining malaria as it occurred. Thisprocess was called demalarialization and was based on the thesis that iftroops were first treated with therapeutic doses and then allowed to havetheir malaria relapses they would develop an immunity and so overcome thedisease. This regimen was undertaken by the 2d Marine Division, the AmericalDivision, the 147th Infantry, and other troops who had been on Guadalcanalduring the malaria epidemic. It resulted in an enormous amount of malariabefore it was abandoned in favor of continuous suppressive therapy for heavilyseeded troops. The rehabilitation period of units who were subject to thisprocedure was approximately double the time estimated for this purpose andmeant a serious decrease in the number of available combat troops.
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Malaria was serious enough for the Allies, but it was far worse for the Japanese; the few prisoners taken were almost invariably malarious. For example, 9,000 Japanese died ofdisease--malaria, malnutrition, beriberi, and dysentery--on Guadalcanal; 4 this was nearly one-half of all their dead on this island.
Other insect-borne diseases which occupied the attention of the antimalaria organization were dengue fever, filariasis, and tsutsugamushi disease. The importance of denguetended to be obscured by the deluge of malaria; actually, dengue could anddid cripple a military force for short periods more rapidly and more effectivelythan did malaria. Filariasis also led to the medical evacuation of many thousandsof troops. Rodent control was undertaken to prevent the spread of epidemicdiseases which were harbored by rats or their ectoparasites as well as toprevent the economic loss by large rat populations. The control of all thesearthropodborne diseases became the responsibility of the South Pacific Malariaand Insect Control Organization.
Antimalaria organization .- The South Pacific Malaria and Insect Control Organization5 was developed to meet the peculiar needs of a mixed Army-Navy-Marine-NewZealand combat force engaged in a series of amphibious operations on 11 malarious islands scattered over many thousands of square miles of ocean (maps 23 and24). This organization had several unusual features which were important toits success and which are briefly noted, as follows:
1. The mixed service character greatly facilitated the best utilization of scarce technical personneland aided the supply problem by making it easier to draw available suppliesfrom all services and to distribute them as needed.
2. The chain of commandwas unusual for a medical organization in that the senior malariologist (Navy)was on the staff of ComSoPac (Commander, South Pacific) and in that on eachbase the reports and recommendations of the senior base malariologist weresubmitted directly to the island commanders with copies to subordinate servicecommands.
3. Malaria control headquarters were established at the theater level and on each large base, although there was no table of organization and equipment for such groups. The theater malariologist and his staff were responsible for recommending assignment of scarce personnel and for establishing uniform policies regarding control measures and supplies.
4. The last unusual feature was the amount of autonomy and initiative allowed to the local malariacontrol groups on each island base.
Malaria control activities. - From the very beginning of planned malaria control in theSouth Pacific Area, the approach was primarily one of control of the mosquitoesresponsible for transmission, with suppressive medication
4 Miller, John: Guadalcanal: The First Offensive. United States Army in World War II.The War in the Pacific. Washington : U.S. Government Printing Office, 1949.
5 This organizationwas first known as "South Pacific Malaria Control," and later as "South PacificMalaria and Epidemic Control."
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as a secondary insurance factor. Theexact sequence in which measures directed against mosquitoes could be applieddepended upon such factors as supplies, manpower, and authority to undertakethe work; once these problems were solved, the mosquito was attacked withall these weapons in combined offensive.
The basic control measure, and that usually first initiated, was larval control by larvicides. Until mid-1944, the chief larvicide was diesel oil, applied by knapsack-type sprayers and vehicle-mounted power sprayers. After the advent of DDT, which became generally available about July 1944, airplane spraying was utilized effectively for elimination of larval populations. Coupled with the larvicidal program was a systematic program of reduction of water surfaces through drainage,road-rut elimination, stream cleaning, and installation of flumes to permitfluctuation of water level in lagoons along the beaches. Through these twogeneral methods, the control of anopheline breeding became highly effective.
The control of adultpopulations of Anopheles was at first limited to spraying with petroleumbase insecticides by hand-operated "flit guns," by the use of Aerosol bombs,and by barriers, such as bed nets and screens. Head nets were never widelyused, nor were repellents, and the degree of
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MAP 24.- Malariousislands of the South Pacific Area
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malaria control attained by these meansis considered negligible. During the latter half of the war in the SouthPacific, DDT was widely used as a residual spray in living quarters, messhalls,latrines, and native quarters.
The systematic indoctrinationof troops in the principles and practices of malaria control was, in thefinal analysis, probably as important an undertaking as any phase of malariacontrol. This training not only made possible a great extension of mosquitocontrol activities but also paid dividends in the observance of personalprotective measures, which at first were completely ignored. The successof the malaria control activities resulted from the multiple-faceted approachto the problem by many individuals.
MILITARY DEVELOPMENT
Mission
The Allied Armed Forces in the Pacific area were ordered on 2 July 1942 by the U.S. Joint Chiefsof Staff 6 to mount a limited offensive to stop the southward advanceof the Japanese toward the sealanes between the United States, New Zealand,and Australia. The immediate objective was to obtain control of the Guadalcanal-Tulagiarea where the Japanese were beginning the construction of an airfield (Guadalcanal)and had established a seaplane base (Tulagi). The ultimate objective of Alliedwar effort in this area for the next 2 years was to be the capture or neutralizationof Rabaul as a Japanese stronghold.
It is to be recalled that the Allies had agreed to make their first major effort in Europe against Germany; meanwhile, the operation against Japan had to take a secondary placeand was limited by the ships, troops, and supplies which could be spared.Furthermore, the initial surprise achieved by the Japanese gave them an extraordinaryadvantage which in less than 12 months of war enabled them to overrun andcontrol a huge area of land and ocean. This area, with Japan as the hub,swung in a great southwestward arc from the western Aleutians through Guadalcanalto the southern tip of New Guinea and thence through the East Indies to themainland of Asia. The Allies and particularly the United States were unreadyin many ways for this onslaught. Our lack of preparedness to handle the malariaproblem and our failure even to realize how important malaria would becomewere symptomatic of the more general unreadiness.
The division of responsibilityfor operations in the Pacific is shown in map 23. The South Pacific Areawas commanded first by Vice Adm. Robert L. Ghormley and, subsequently, byAdm. William F. Halsey, Jr.; they were responsible to Adm. Chester W. Nimitz,the Commander of the Pacific Ocean Areas. The Southwest Pacific Area wasunder the command of Gen. Douglas MacArthur.
6 See footnote 3, p. 401
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The South Pacific Area and Force was eventually given responsibility for land operations throughoutthe Solomon Islands and the Saint Matthias Group. Its area of authority wasextended by successive orders and attained its maximum extent as shown inmap 24.
Chronological Table of Operations
Early in the War, Allied naval, land, and air forces were gathered as rapidly as possible inthe major nonmalarious bases--Samoa Islands, New Zealand, Fiji Islands, andNew Caledonia. Theater headquarters were first established in New Zealand and later were moved to New Caledonia. Subsequent land operations were onmalarious islands in the New Hebrides, Solomon Islands, and Saint Matthias groups. The chronological table for occupation of malarious bases was as follows:
Unopposed landings in New Hebrides:
Efate - advance grouplanded, 18 March 1942.
Espí ritu Santo- 4 May 1942.
Assault landings in Solomon Islands and Saint Matthias Group:
Guadalcanal - 7 August1942. Island secured, 9 February 1943.
Tulagi and adjacent island - 7 August 1942. Secured, 9 August 1942.
Russell Islands - 21February 1943 (no land opposition).
New Georgia (Rendova landings) - 30 June 1943. Secured, 26 August 1943.
Vella Lavella - 15August 1943. Secured, 9 October 1943.
Treasury Islands -7 October 1943. Secured, 10 October 1943.
Bougainville (EmpressAugusta Bay area) - 1 November 1943. Perimeter defense until V-J Day.
Green Island - 15 February1944. Secured, 20 February 1944.
Emirau Island, SaintMatthias Group - 20 March 1944. No land opposition.
"Secured" was the official term to denotethe end of effective enemy opposition. The length of time between the initialattack and the date when each island was declared secured approximates theperiod during which malaria control activities were carried out under combatconditions.
Rear Area and Air Force Installations
The rear area installationsof greatest importance were on New Caledonia, which was the headquartersof the South Pacific Area Command. This island was 1,000 miles south of Guadalcanal.During the early part of the campaign, it was an important transshippingand supply base. But, after Guadalcanal was secured, many supply activitieswere gradually moved to that island which became the staging area for successiveattacks on Japanese-held islands to the northwest.
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There were excellent harbors at Nouméa in New Caledonia, at Havannah Harbour in Efate, andat Segond Channel in Espíritu Santo. Major naval supply and repairdepots were developed at Nouméa and at Espíritu Santo, andan advance naval base was established at Tulagi in the Florida group. Allthese were malarious areas except New Caledonia, and even there mosquito controlactivities were required to prevent dengue fever which caused sharp epidemicsbefore it was brought under control.
AREA CHARACTERISTICS AS THEY PERTAIN TO MALARIA AND ITS CONTROL
Physiography
Extent and area . - The malarious areas here discussed comprised 11 bases in the South PacificArea. Although the total occupied area on these bases consisted of only approximately350 square miles of territory, they were scattered over vast reaches of thePacific Ocean (map 24). These islands, from Efate, in the New Hebrides toEmirau in the Saint Matthias Group, extend in a long chain from 17o30' south longitude and l68o 30' east longitude to 1 o 8' south longitude and 1500 east longitude. The totaldistance from Efate to Emirau is approximately 1,550 nautical miles. Thetotal area of the New Hebrides is 5,700 square miles; that of the SolomonIslands is 18,000 square miles. Espíritu Santo, the largest islandin the New Hebrides, is 76 miles long and 40 miles wide. Efate, at the southernmosttip of the New Hebrides, is 26 miles long and 14 miles wide. Bougainville,largest of the Solomon Islands, is 120 miles long and averages 40 miles inwidth; while Guadalcanal, the second largest of the Solomons, is 90 mileslong and has an average width of approximately 30 miles.
The military occupied area of Efate and Espíritu Santo included approximately 40 square mileson each base. On Guadalcanal, approximately 110 square miles of territory on the northwest coast were occupied, although combat Operations had extended well beyond the area of occupation. On Bougainville, the area originally occupiedtotaled about 30 square miles but was later expanded to 50 square miles.Approximately 30 square miles were occupied on Empirau. The military occupationof other South Pacific bases involved relatively small areas, usually lessthan 20 square miles each.
Types of terrain and watered areas. - With the exception of Emirau, Green, and Treasury Islands, which are coral, all the malarious bases occupied during the South Pacific campaign are of volcanic origin and are mountainous. On Bougainville, Mount Balbi reaches to 10,171 feet; on Guadalcanal, Mount Popomanasiu reaches 8,005 feet; and on Espíritu Santo, Mount Tabwemasana reaches 5,940 feet. Occupied portions of the bases were usually limited to relatively narrowcoastal strips, which consisted, for the most part, of coral uplifts or alluvialplains. In the occupied portions of some of the bases, the hills extendednearly to the sea; on others, such as Guadalcanal, the major portion
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MAP 25.- EspírituSanto, New Hebrides.
of the occupied area was on an alluvial plain from 1 to 10 miles in width. There are no large rivers and only a fewpermanent streams on the smaller islands, but the three largest bases representeddifferent and varying types of terrain and deserve more detailed discussion.
The occupied area on Espíritu Santo (map 25) consisted of a long, narrow coastal strip on the southeastern portion of the island, extending from Turtle
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MAP 26.- Guadalcanal,Solomon Islands.
Bay on the north to the Renee River on the south. This area is underlaid with coral, and the hills extend nearly to the sea. There are numerous large streams, some of which emerge near thecoast from huge coral craters. The longer streams, arising in the mountains, are swift flowing and subject to considerable variation during times of heavyrainfall. The short streams, emerging from the coral craters, have a fairlyuniform flow but are subject to considerable tidal influence, their leveloften fluctuating as much as 3 feet each day for a mile or more inland andsometimes to the crater source. A considerable part of the occupied areaof Espíritu Santo consisted of coconut, coffee, and cacao groves.
The occupied area on Guadalcanal (map 26) extended from the Balasuna River, near the north centralportion of the island, to beyond Doma Cove toward the northwestern tip andincluded about 45 miles of coastline. The broad alluvial plain on the northcentral coast of Guadalcanal becomes progressively narrower from a widthof about 10 miles between the Balasuna and Metapona Rivers to less than amile at the Lunga River, the largest of the rivers in this area. West ofthe Lunga, the plain narrows rapidly and beyond Kukum Point consists largelyof a narrow fringing strip. The broad portion of the plain is transectedat intervals of about 3 miles by major drainage courses arising in the mountainsto the south. Between these rivers (Balasuna, Metapona, Nalimbiu, Tenaru,and Lunga) are numerous sluggish meandering streams.
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The beaches east of the Mataniko River, the first river west of the Lunga, are of dark volcanic sand and slope rather gently to the ocean floor. West of the Mataniko River, the beaches are of relatively coarse gravel and are more precipitous. The soil of the alluvial plain is a fine, black silt, underlaid by a yellow claysubsoil. The topsoil, when undisturbed, is capable of absorbing and holdingan enormous amount of water but once packed by vehicular traffic becomeshighly impervious. All the small streams between the Balasuna and the Lunga,and many of those to the westward, were periodically blocked at the mouthby sandbars built up by surf action. The coastal lagoons and swamps thusformed often remained blocked for long periods of time, permitting the developmentof aquatic vegetation and making ideal breeding places for Anopheles farauti. West of the Mataniko River, streams are generally smaller than in thenorth central part of the island but are less likely to become blocked bysandbars at the coast because of the more precipitous beach and the obliqueocean currents striking the coast in this area. Many of the small drainagecourses west of the Mataniko are dry during a part of each year.
The occupied portion of Bougainville (map 27), near Empress Augusta Bay on the southwest coast, is a recently uplifted area. The soil is volcanic sand for some miles inland, and the terrain consists of a series of sandy terraces, representing old beachlines. The eastern portion of the area contains some steep foothills. Thesand terraces are transected by a few rivers and small streams, some of whichwere clogged by the accumulated debris of centuries with the result thateach terrace contained a series of fresh-water swamps. A high water table,which quickly filled foxholes and shell and bomb craters, characterized muchof the area before cleaning of drainage courses, but subsoil drainage wasgenerally good. As on Guadalcanal, streams were often blocked at the mouthby sandbars to form coastal lagoons.
Prevailing vegetationcovers. - The occupied malarious bases of the South Pacific lie withinthe true tropic belt, and the vegetation of these islands is accordinglyinfluenced greatly by the climate of the tropics. For purposes of discussion,it is convenient to distinguish between the low coral formations, such asEmirau, Green, and Treasury Islands, and the larger volcanic islands thatconstituted the remaining bases.
Because of the veryporous condition of the soil, the coral islands are without tropical rainforests and have relatively little dense growth that approximates true jungle.The vegetation consists primarily of coconut palms, low-growing brush, grass,and weeds. More luxuriant, junglelike growth occurs in the marshy areas ofthe islands. Vegetative cover was not an important factor in malaria controloperations on these islands.
The larger volcanic islands of the South Pacific are typically covered with heavy rain forests except along the coast where narrow strand formations occur. The coastal areas,and sometimes the inland areas as well, are often occupied by extensive plantingsof coconut palm, coffee, and cacao. There
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are occasional rubber plantations andother cultivated tropical plants. Since plantation areas are usually leveland open, they were widely used for bivouac areas and supply dumps. As such,they became an important part of the malaria control problem.
The coastal strand formation consists of two general types. Around the tidal mudflats at the mouths of the numerous permanent streams, mangrove swamps are common. These mangrove swamps were of little importance ex-
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cept in the innermost portions where tidal action was minimal and relatively fresh water permitted the growth ofaquatic vegetation. On the beaches, between streams, the strand formation consists of coconut palms intermixed with scattered large forest trees growingto a height of 60 feet or more. Occasionally, there are huge banyan trees.In most places, a dense undergrowth extends to within a few feet of the hightide line, and, except on the more barren shores, the undergrowth withinthe strand formation is almost impenetrable. The secondary plants makingup the strand formation contain such forms as Hibiscus, Pandanus, and a herbaceous ground cover of tangled vines, grasses, sedges, and other low plants. The entire formation is narrow, often no more than a few yards in width.
Wherever they occurredand had been maintained, plantations were relatively open at ground level.Before military occupation on most bases, and throughout the occupation on some, cattle were widely grazed in cocoanut groves. Grazing together with periodic removal of secondary undergrowth maintained such groves as open, parklike areas offering easy passage for traffic of all kinds. Coconut grovesthat were not grazed or otherwise maintained quickly developed into a thicktangle of young cocoanut palms, brush, and tall grass. Coffee and cacao plantations,being heavily shaded by towering jungle trees, had somewhat sparse groundcover. The orderly arrangement of the plantings and their excellent camouflagequalities made them ideal for supply dumps. When used for that purpose, however,roads were but rarely constructed until after long use. This resulted inmile after mile of water-filled ruts caused by the movement of heavy vehiclesbetween the rows of trees. Plantations in general, and coconut plantationsin particular, became one of the big problems from a malaria control standpoint.
The true rain forestformation consists of a towering canopy of trees reaching to 150 feet inheight, with successively lower layers of trees which supply a very denseshade at ground level. Various climbing plants, some of which extend to theuppermost canopy, form an undergrowth that is difficult to penetrate exceptalong established trails. Off the trails in the jungle, where it is necessaryto hack a way through the undergrowth with machetes, a half-mile per houris considered a rapid march speed. Even along trails, rapid movement is impossiblebecause of the slippery footing, obstructing roots, and the long, whiplikeextensions of the rattan palm that hang across the trails and grasp at clothingor flesh with sharp, stout, recurved spines. Because of high humidity, lackof aeration, and difficulty of clearing these areas, the true rain forestwas little used for bivouac purposes and only to a limited extent was itnecessary to extend malaria control activities into this type of growth.
The plant formations of Guadalcanal,7 and to a limited extent those of Tulagi, differ considerably from those encountered on others of the major
7 Pendelton, R. C.: The Rain Shadow on the Plant Formations of Guadalcanal. Ecological Monographs 19: 75-93, 1949.
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South Pacific islands. Guadalcanal liesathwart the prevailing trade winds in the area, and the high mountains inthe central part of the island, forcing the air upward, cause heavy rainfallon the south side of the island and diminished rainfall on the northwestcoast. Within this area of rain shadow effect, which extends to Tulagi, thereis a greater seasonal variation in rainfall than is characteristic of partsof the island not influenced by high elevations in the path of the tradewinds, and a total rainfall somewhat less than is required to support tropicalrain forests. This results in the absence, from the northwest coast of Guadalcanal,of true rain forest formations and accounts for the extensive grasslandsof the coastal plain and lower hills. Because these extended grasslands andassociated vegetative features had a profound influence on the malaria controlproblem on Guadalcanal, they are discussed in some detail.
On the eastern partof Guadalcanal, where seasonal variation and total rainfall is not influencedby high elevations in the path of prevailing winds, there is dense rain forest.From the Berande River, some 4 miles east of the limits of the occupied area,to the northwestern tip of the island, the vegetation of the north coastis influenced by the rain shadow caused by mountains. This portion of theisland is characterized by extensive grasslands, while the high central partof the island and the south side are covered by rain forests. 'The northwestcoastal area is transected by numerous rivers and smaller streams, and alongmost of these there is a strip of forest connecting the forests of the hillswith the narrow coastal-strand formation.
Although these foreststrips along stream courses are narrow, being in some places only a few hundredfeet in width, they consist of much the same type of vegetation as is encounteredin typical rain forests. These jungle strips rise abruptly from the grasslandsto a height of 100 feet or more, often with scattered taller trees reachingmany feet higher. The height and uniformity of the vegetation increases withthe width of the jungle zone bordering the stream, and forest belts alongthe larger permanent streams present a relatively uniform canopy. The vegetationbordering temporary streams usually consists of a narrow belt of trees ofvarious heights, so that from a distance the canopy presents a ragged appearance.Because these forest belts admit a considerable amount of sunlight, the undergrowthis frequently more dense than that of true rain forest, particularly at theforest edge. From the standpoint of mosquito control operations, these junglestrips were comparable to true rain forest. On Guadalcanal, they were widelyused for bivouac and supply areas when cocoanut palm groves, were not available.
The extensive grasslandsare the dominant vegetative feature of the northwest coast of Guadalcanal.Between the Berande and Lunga Rivers, they occupy the major portion of theflat coastal plain and extend inland for several miles. well into the foothills.West of the Lunga, where the coastal plain becomes progressively narrowertoward Cape Esperance, the grasslands are largely on the rugged foothills.The dominant grass in these areas grows to
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a height of 4 to 6 feet, forming atangled mass of vegetation that is often more difficult to penetrate on footthan is the jungle. On the flat alluvial plain between the Balasuna and LungaRivers, these open grasslands offered an inviting area to drivers of vehicles,either on legitimate business or aimless exploring. Soon the entire areawas crisscrossed with innumerable trails, most of which became badly ruttedand held water either periodically or constantly. Once a trail became impassablebecause of rutting, a new trail parallel to the old one would be started,adding to the miles of ruts. The elimination of these road ruts, and theclosure of the grasslands to indiscriminate driving, became a major malariacontrol problem on Guadalcanal.
Climatic Features
In general, it maybe said that the climatic features of the South Pacific islands favor malaria.The absence of the vector of malaria, and hence the absence of the diseasefrom many of the smaller islands in the malarious zone, appears to be correlatedwith physiographic rather than climatic features. Although rainfall is abundantthroughout the area and the temperatures are high and fairly uniform, manyof the smaller coral islands have no permanent fresh water suitable for anophelinebreeding.
Rainfall.- On all bases, the total yearly rainfall was high, usually exceeding 100 inches.This factor, coupled with a constantly high humidity, served to keep thesoil well saturated during the greater part of the year. The terms "dry season"and "wet season" are relative; during most months of the year, there wassufficient rainfall to maintain numerous small surface pools of water. Duringthe period from June to August, the intertropical front is north of the Equatorand the prevailing winds are from the southeast. This is the so-called dryseason. From December to February, when the intertropical front is southof the Equator, the prevailing winds are from the northeast. The periodsfrom March to May and from September to November are characterized by unsettledweather when the. doldrums and their intertropical fronts are moving acrossthe Equator. Marked seasonal variation in rainfall, such as occurs on thenorthwest coast of Guadalcanal, may have been due to local topographic features.During the so-called wet season, heavy rains may be expected daily for asmuch as a week at a time. As much as 36 inches of rainfall in 1 month hasbeen recorded for Bougainville (Kieta) ; the total rainfall for March 1944on Espíritu Santo was 28 inches, of which 10.5 inches fell duringone 24-hour period on 27 March.
The influence ofrainfall on the problems of malaria control is difficult to evaluate, butit was undoubtedly the most important single factor in causing seasonal variationsin the problems. Periods of heavy rainfall, causing flushing of drainagecourses and opening of some lagoons, resulted in the temporary eliminationof anopheline breeding from most streams. The great increase in surface waterthat resulted from heavy rains served to disperse current larval
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populations and gave the impression that there was some cessation of breeding. On most bases, peak anopheline populations usually occurred soon after the cessation of heavy rains. A numberof factors apparently contributed to this situation. The stabilization ofabundant water surfaces combined with increased sunlight and its resultant effect on the development of plant life to make conditions ideal for larval development. Larvicidal crews were frequently unable to obtain complete coveragefor several days or weeks following heavy rains.
Temperature . - There is little variation in temperature at sea level in the Solomon Islands, and the daily temperature range is remarkably uniform throughout the year. The maximum daily temperature rarely exceeds 94 0 F.,and the minimum is seldom below 67 0 F. The usual daily temperaturevariation was about 20 0 F. from a high of about 90 0 to a low of about 70 0 F. These temperatures, together with ahigh relative humidity of approximately 80 percent, provided almost optimalconditions for mosquito development. At no time were temperatures in theSolomon Islands bases so low as to be considered unfavorable to anophelinebreeding.
Temperatures in theNew Hebrides exhibited a greater range of daily variation, as well as lessuniform daily change throughout the year. Temperatures as low as 530 F. were recorded at Segond Channel on Espíritu Santo, andas low as 58 0 F. on Efate. Maximum temperatures of 98 0 and 95 0 F., respectively, were recorded for these two bases.Because the periods of both low and high temperatures were relatively brief,it is doubtful if these extremes had any appreciable effect on mosquito development.
Local Population
New Hebrides . - The population of the New Hebrides in 1939 was given as 218 British, 687 French, 2,282 Asiatics (Tonkinese, Chinese, and Japanese), and about 40,000native Melanesians. Of the Melanesians, about 4,000 lived on Espíritu Santo and 1,700 on Efate, mostly in small, independent villages scattered through the islands.
During the first part of the occupation of Efate and Espíritu Santo, the troops were bivouacked near labor camps of natives who were heavily seeded with malaria, and in areas where anophelines were numerous. Later on, troop concentrations were kept away from local communities as much as possible, but this could not be done in outlying areas.
In the New Hebrides, yaws, hookworm infestation, malaria, dysentery, and tuberculosis are endemic. Wucheria bancrofti is also present. The results of surveys by themalaria control organization follow.
Solomon Islands and Saint Matthias Group . - The natives of the main Solomon Islands andthe Saint Matthias Group are Melanesians. In 1939, the population of theSolomons, including Bougainville, was given as 500 Caucasians, 140,000 Melanesians,and 200 Chinese. At the time of Allied
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occupation, most of the Caucasians hadfled. The population of Guadalcanal was about 20,000 and that of Bougainville about 45,000. The natives lived rather primitively in small villages, family groups, or families.
When the fighting began in the Solomons, the local inhabitants left the combat areas. After the islands had been secured, they were usually prevented from reentering the troop area. Native labor camps, however, were at first often located inthe troop area. Later, some were moved away. Local traders also visited thetroop areas during the daytime to trade, but were not permitted to sleepthere.
Solomon islanders are heavily infected with tuberculosis, yaws, and hookworms. In surveys of2,500 Guadalcanal residents carried out by military malaria control personnel,22 percent were found to have W. bancrofti microfilariae in theirblood. Malaria is hyperendemic among the natives.
Incidence of malaria. - Data on the incidence of malaria in the New Hebrides, Solomon Islands,and Saint Matthias Group have been given by Levine and Harper. 8 In addition, the report of Sayers 9 on malaria in the New GeorgiaGroup, Solomon Islands, became available during the war. Sayers, who hadconducted a hospital at Munda and later at Vella Lavella, Solomon Islands,from 1927 to 1934, had treated 741 parasite-positive natives from a populationof about 6,000. In these clinical cases, Plasmodium falciparum was present in 44 percent, Plasmodium vivax in 32 percent, Plasmodium malariae in 18 percent, and undetermined species in 6 percent. The splenomegalyrate among 365 children was 73 percent. Clinical malaria was not common inNew Georgia natives over 30 years of age.
The malaria rates reported by the military malaria control personnel were based on single-smear surveys made on thick smears stained with Giemsa stain. They are not comparable with Sayers figures, since his were based on clinical cases.
The prevalence ofmalaria observed in these surveys is given in table 59. The surveys on nativesof Malaita and San Cristobal, Solomon Islands, and one of those on Guadalcanalwere made on adult male laborers who were living in labor camps on Guadalcanalat the time of examination. The parasite rate was relatively low in thesethree surveys, ranging from 7 to 11 percent. Since the parasite rate amongthe Guadalcanal villagers was 52 percent and the rate among the Guadalcanallaborers was 10 percent, it is clear that the prevalence of Plasmodiumin healthy, adult laborers cannot be taken as indicative of the rateamong the people as a whole.
Plasmodium species distribution .- The species of Plasmodium encountered in the surveys are given intable 60. P. vivax was the most common on all islands except Emirau,being found in 41 to 88 percent of the positive
8 Levine, N. D., and Harper, P. A.: Malaria and Other Insect-Borne Diseases in the SouthPacific Campaign, 1942-1945; IV. Parasitological Observations on Malariain Natives and Troops, and on Filiariasis in Natives. Am. J. Trop. Med. 27(suppl.) : 119-128, May 1947.
9 Sayers, E.G.: Malaria in the South Pacific with Special Reference to the Solomon Islands.New Zealand Government Printing Office, 1943.
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smears from these islands. The most common species on Emirau was P. falciparum, which was present in 45percent of the smears. On the other islands, this species was found in 6to 37 percent of the positive smears. P. malariae was not found onEfate, Treasury, Malaita, or San Cristobal Islands. However, surveys on thelast two islands were made on adult laborers. P. malariae comprised25 percent of the positive smears on Emirau and 20 percent of those on Savo.Its prevalence on the other islands ranged from 0.5 to 12 percent.
TABLE 59.- Prevalence of malaria parasitemia on South Pacific islands
Relation of ageto prevalence of malaria and species of Plasmodium . - In surveys made on Guadalcanal, 91 percent of 44 children from birthto 5 years of age, 72 percent of 51 children from 6 to 15 years of age, and38 percent of 96 persons over 15 years of age carried plasmodia in theirblood. Similar decreases in prevalence with age were found on Savo, Green,and the Russell Islands. On Guadalcanal, the most common species in all agegroups was P. vivax. In the youngest age group, P. falciparum was the least common species, but its prevalence was higher in the two oldergroups, while that of P. malariae decreased with age. The prevalenceof P. falciparum also increased with age on the other islands butthat of P. malariae was variable.
Splenomegaly rates . - Splenomegaly was observed in 61 percent of 110 residents on Ef ate,57 percent of 101 on Espíritu Santo, 73 percent of 258 on Guadalcanal,70 percent of 37 natives on Florida, 57 percent of 219 laborers
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TABLE 60.-Plasmodium species in South Pacific surveys
from Malaita, 66 percent of 193 residents on the Russells, 75 percent of 500 natives on Bougainville, 57 percent of219 laborers from San Cristobal Island, 34 percent of 37 villagers on Treasury,65 percent of 542 natives from Green, and 85 percent of 263 on Emirau.
Mosquito Vectors of Malaria
Six species of Anopheles are known to occur in the islands of the South Pacific Area.These species and their recorded distribution are as follows:
Area
Anopheles farauti Laveran 1902............................................Allmalarious bases.
Anopheles koliensis Owen 1945............................................Guadalcanal,north coast.
Anopheles lungae Belkin and Schlosser1944.........................Guadalcanal, north and northeast coast; EmpressAugusta Bay, Bougainville;Munda, New Georgia.
Anopheles nataliae Belkin 1945.............................................Guadalcanal, north coast.
Anopheles punctulatus Dönitz 1901.......................................Guadalcanal, north and south westcoasts; Empress Augusta Bay, Bougainville.
Anopheles solomonis Belkin, Knight,and Rozeboom 1945.....Guadalcanal, northwest coast; Munda, New Georgia.
Characteristics ofmalaria vectors
In the South Pacific Area, the principal vector of human malaria, and probably the only one ofmilitary importance, was A. farauti Laveran (fig.
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53A). Anopheles koliensis Owen (fig. 53B) was known to be strongly anthropophilic and thus potentially animportant vector but of limited geographic distribution. In the limited areaon Guadalcanal, in which it is known to occur, it may have been of some consequenceduring the period of combat and early occupation. Available information indicatesthat other species of Anopheles were not involved in the transmissionof malaria to troops.
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Breeding habits. - Anopheles farauti larvae usually occurred in greatest numbers andhighest concentrations in sunny, slightly brackish lagoons in association with emergent aquatic vegetation and surface debris. The species also utilized almost every conceivable type of aquatic habitat with the exception of artificialcontainers, tree holes, open moving water, and highly saline water. On occasions,A. farauti larvae were even found in artificial catchments when thesewere of sufficient size to approximate ground pools. The ability of the speciesto utilize these many types of habitats greatly influenced its importanceas a malaria vector. It occurred abundantly in permanent or temporary surfacewater catchments of all kinds, in tidal and fresh-water swamps and lagoons,and to a lesser extent in streams, seepage areas, and open wells. Althoughit preferred sunlit water, it also occurred in rather heavily shaded areas.The larval developmental period was short, especially during the so-calleddry season when prolonged periods of sunlight considerably increased thewater temperature of typical breeding habitats.
Observations on Guadalcanalshowed that under favorable circumstances A. farauti could completedevelopment from egg to pupa in 5 days, and from egg to adult in 8 days.The normal developmental cycle from egg to adult was usually considered tobe between 7 and 10 days, and larvicidal schedules were arranged accordingly.The ability of A. farauti to initiate an epidemic of malaria is clearlyillustrated by the experiences of combat troops during the early phases ofthe Guadalcanal Campaign.
Insofar as they areknown, the larval habitats of A. koliensis are similar to those ofA. farauti, although information is not available to indicate whetheror not A. koliensis adapts itself to the wide range of habitats thatare utilized by A. farauti. During periods of prolonged rainfall, A. punctulatus larvae are found in typical A. farauti habitats, but during the dry season this species disappears from the coastal section of Guadalcanal. Anopheles lungae occurs in coastal swamps and seepage areas and shows a decided preference for shaded habitats. Both A. solomonis and A. nataliae occur in the low foothill section along the northwest coast of Guadalcanal, the former having been collected from potholes in acoral streambed and from seepage areas. Both species were usually found inclear water, densely shaded.
Habits of adult Anopheles. - All the species of Anopheles encountered in the South Pacific Area werenocturnal in their biting habits, although under favorable conditions oflow light intensity daytime biting by A. farauti was not uncommon. This species was observed to bite as early as 1500 hours in jungle area ona cloudy day and as late as 0730 hours in thatched huts on a relatively brightday. Normally, the biting activities of A. farauti were limited tothe period from dusk to shortly after dawn. Practically all Anopheles caught in routine night-biting catches on Guadalcanal were A. farauti, except for the relatively limited area in which A. koliensis wasknown to occur.
Man is generally considered to be the normal host of A. farauti perhaps in part because there are usually few other large mammals available in the
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South Pacific islands. However, host preference tests conducted on Efate showed that the species fed readily oncattle, horses, goats, pigs, dogs, and chickens. Available evidence alsoindicates the probable existence of host-adapted strains of A. faraution Guadalcanal. In 1944, numerous attempts were made to attract adultA. farauti to humans at night in the vicinity of an abandoned plantationnear the mouth of the Balasuna River. Although weather conditions were favorablefor mosquito activity, and high larval and pupal populations were known toexist in nearby lagoons, no adults were seen. Similar observations were madein other areas remote from existing human habitations. It was also repeatedlyobserved that adults reared from larvae collected outside the zone of normalhuman activity fed rarely or not at all on humans under laboratory conditions.On the other hand, specimens in captivity reared from the eggs of gravidfemales captured in native villages usually fed readily on humans. The successfulcolonization of A. farauti for laboratory study was usually accomplishedby starting the colony with such material. Inadequate facilities and lackof time prevented detailed study of this interesting and probably importantphenomenon.
As previously indicated,A. koliensis was strongly anthropophilic and frequently taken in nightcatches with humans as bait, and in the tents and thatched huts of nativelaborers. Anopheles punctulatus and A. lungae were but rarelyattracted to humans, even when existing populations were high.
The daytime resting places for both A. farauti and A. koliensis, except for recently engorged females, apparently consisted of any cool, moist, shaded place. Becauseadult population sampling is generally thought to be the most accurate measureof an existing mosquito population, many efforts were made to seek out thedaytime resting places of A. farauti in the South Pacific. Althoughalmost every conceivable type of habitat was explored, at no time were adultsencountered with sufficient consistency or in sufficient numbers for thismethod to be used as a basis for measuring the effectiveness of a controlprogram. On the day following a nocturnal blood meal, A. farauti and A. koliensis females frequently remained in the dark parts of native huts or tightly closed tents but would leave by dusk or shortly thereafter. There was little evidence to indicate that blooded females lingered after obtaining a meal in open tents such as were usually used by troops, in thatchedshelters without walls, or in the more open type of native huts.
Observations conducted during 1944 on Guadalcanal, involving daily counts of the Anopheles resting in pyramidal tents used to house Melanesian laborers, showed thatthe population remained fairly constant but consisted almost entirely offreshly blooded females.
Anopheles punctulatus and A. lungae were observed to rest during the daytime on themoist, lichen-covered surface of the buttressed bases of huge forest treesin deep jungle shade. Only rarely were specimens of A. farauti observed in such places.
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Results of Combat and Occupation on Malaria Potentialities of the Area
The full significance of the changes which led to increased mosquito breeding under conditions ofcombat and occupation in the South Pacific Area are appreciated only whenviewed in contrast to the conditions prevailing in jungle or tropical areasoccupied only by local populations. Before invasion or occupation, extensivebreeding of A. farauti was limited largely to coastal lagoons andnative clearings along inland streams, if one may correctly judge by thesituation pertaining in those areas not disturbed by occupation forces. Althoughmosquitoes were almost invariably present in isolated native villages, thenumbers were small.
With the advent ofcombat and occupation, and its associated myriad activities of supply andmovement, there were soon created innumerable water catchments such as shelland bomb craters, abandoned gun positions and bomb shelters, foxholes, andruts made by vehicular traffic. Airfield construction and roadbuilding, oftenhastily done, created further impoundment of water. Once created, these watercatchments could never be quickly eliminated because of the limited amountof personnel and equipment that could be assigned to malaria control activities.Anopheles farauti soon utilized these many water surfaces for larvaldevelopment, with the result that there was a rapid and enormous increasein the anopheline population of the area. Because personal protection fromthe bites of mosquitoes during combat and early occupation was difficultto attain, a high percentage of the female Anopheles were able toobtain blood meals, further enhancing the mosquito breeding and malaria transmittingpotential.
MALARIA EXPERIENCE
Admission rates formalaria in Army personnel in the South Pacific theater are given in tables61, 62, 63, and 64. Since these rates include both malarious and nonmalariousbases, they do not give a true picture of the situation in the command. SinceArmy, Navy, Marine, and Allied troops lived in close proximity and sincedifferent islands differed markedly, a much better picture of the situationis given if the rates of all troops are considered on each island. Ratesin these tables refer to clinical malaria cases and do not indicate the actualmalaria infection rate. Many troops on suppressive Atabrine therapy did notdevelop clinical malaria until after they had stopped taking the drug. Anindication of the true infection rate was obtained in units which were takenoff suppressive Atabrine therapy after having become more or less heavilyseeded with malaria.
Efate . -Efate was the first malarious island to be occupied in the South Pacific. Troops landed, in March 1942, to build an airfield. They were bivouacked neara native labor camp in an area where anophelines were numerous. They lackedsufficient bed nets and were required to work at night.
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Furthermore, they did not realize how serious malaria could be. The malaria rate reached 2,678per 1,000 per annum in April (table 61). Quinine was the only antimalarial drug available, and in May about one-half the troops were ordered to take 0.33 gm. quinine daily; this amount was later increased to 0.66 gm. daily. These amounts failed to suppress the disease satisfactorily, and in July, 0.4 gm. Atabrine weekly was begun. The first malaria control personnel, oneNavy officer and three enlisted men, arrived on 28 July 1942. Malaria ratesdecreased to 982 per 1,000 per annum in May and continued to decline untilthey reached a low of 144 per 1,000 per annum in September. This declinewas due to the initiation of insect control measures, to suppressive therapy,and to the onset of the dry season. Atabrine was given to the villagers,and their huts near the troop areas were sprayed daily with a pyrethrum spray.The largest native labor camp was not moved to a safe distance from troopsuntil nearly a year after the original epidemic. Antimosquito work was wellorganized by early 1943, but heavy equipment for semipermanent mosquito controlwork did not become available until 16 months after the first landing.
Suppressive Atabrine therapy was discontinued in September 1942 because of the low malaria rate. The rate promptly increased, reaching 520 per 1,000 per annum in November. Suppressive Atabrine therapy was resumed in November except for lightly seededpersonnel living in screened quarters, and the malaria rate again decreased.In 1943, many of the heavily seeded troops left Efate, and the remainingtroops were withdrawn from poorly controlled areas. By July 1943, the malariarate was 128 per 1,000 per annum, of which only 66 were original admissions(table 62). At this time suppressive Atabrine therapy was discontinued onthe island. The subsequent rates remained low, with a high percentage ofrelapses.
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Espíritu Santo. - This island was occupied without opposition in May 1942. The dry season had begun, and there was very little mosquito breeding near thecampsites. Even though drug suppression was not practiced, no cases of malariawere reported until September. In September, October, and November, freshtroops were camped near heavily seeded natives in anopheline breeding areas.The more exposed personnel were placed on suppressive Atabrine therapy, andthe malaria rate did not rise beyond 255 per 1,000 per annum.10 It reached this level in January 1943, and thereafter declined slowly (table 62). After the original admission rate had reached 109 per 1,000 per annum in May 1943, suppressive Atabrine therapy was discontinued. The rate continued to drop, the original admission rate being 16 per 1,000 per annum in November 1943 and declining still further later on.
A base malaria controlgroup consisting of two Navy officers and eight Navy enlisted men was setup in September 1942. Troop areas were kept as far from local settlements as possible. The inhabitants were given suppressive Atabrine therapy, and their huts were sprayed regularly with pyrethrum beginning early in 1943. Residual spraying of the huts with DDT was begun in mid-1944. An extensive larviciding and semipermanent control program was in operation by mid-1943. It was so effective that after this time it was unusual to find adult anophelines in the main troop areas. Outlying areas, however, continued to be highly malarious,and troops on outpost duty became heavily infected.
Guadalcanal . - The first landing on Guadalcanal was made by Marine units in August 1942.The first Army units arrived in October. At first anti-malaria supplies wereeither unavailable or inadequate, and no significant amount
10 Malaria rates on Espíritu Santo are not comparable with those on the other islands. Only cases contracted on Espírito Santo are included, while on the other islands all cases wherever contracted (except cases among hospitalpatients admitted on an in-transit basis) are included.
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of mosquito control was done. The factthat there were few cases of malaria in August and September led to the feelingthat the disease would be unimportant. No malaria control measures were undertakenduring the early months, partly because of the desperate military situationand partly because responsible officers did not understand how serious ahazard malaria could be. The prevailing attitude was expressed by one highranking officer who said: "We are here to kill Japs and to hell with mosquitoes."
However, the terrain and the results of combat combined to produce ideal conditions for the breedingof enormous numbers of mosquitoes. The combination of abundant anophelinebreeding, a highly malarious source of infection (the native Melanesiansand the Japanese troops), and almost complete absence of antimalaria precautionscaused the malaria rate to rise precipitously to 1,664 per 1,000 per annumin October 1942 and to 1,781 in November (table 61). Malaria remained epidemicfor at least 9 months. Of the estimated 100,000 cases of malaria contractedin the South Pacific, more than three-fifths were probably contracted onGuadalcanal, and most of these during the period October 1942 to August 1943.In July 1943, the malaria rate was 608 per 1,000 per annum, of which 342per 1,000 per annum were original admissions (table 62). The rate droppedto 263 per 1,000 per annum (of which 142 were original admissions) in August1943 and continued to decline steadily thereafter. In February 1944, whenthe original malaria admission rate was 74 per 1,000 per annum, suppressiveAtabrine therapy was discontinued in lightly seeded units. The rate continuedto decrease. By October 1944, about 26 percent of the troops bad been takenoff Atabrine, the total malaria rate was 51, and the original admission ratewas 22 per 1,000 per annum (table 63). By June 1945 over 75 percent of thetroops had been released from suppressive Atabrine, the total malaria ratewas 9, and the original admission rate, 6 per 1,000 per annum (table 64).
A base malaria controlgroup consisting of two Navy officers and eight Navy enlisted men was establishedin November 1942. This organization was later expanded greatly, and Armypersonnel eventually predominated. By far the largest amount of antimalariawork on any island was done on Guadalcanal. By the latter part of 1943, controlwork was well advanced. After that time, adult anophelines were difficultto find in the occupied area except during sporadic infestations.
The most important measure responsible for the great decline in the malaria rate was the extensive mosquito control work, both larvicidal and drainage, which was carried out.Atabrine suppressive therapy lowered the rates in heavily seeded troops. Administrationof suppressive Atabrine and mass therapy to natives, spraying of their huts,and removal of native labor camps from troop areas (not accomplished completelyuntil August 1944) were also helpful. Other factors were the improvementin living conditions for the troops, particularly the provision of screenedquarters, and extensive education in personal malaria preventive measures.
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During the early period, troops which had staged in uncontrolled areas on Guadalcanal for onlya few days and then moved on to other islands often had severe malaria outbreakstraceable to their exposure on Guadalcanal. To prevent this, a troop bivouacarea of about 90 square miles was established in November 1943. Mosquitocontrol was carried out here continually. No organization was allowed tobivouac outside this area without special permission.
Tulagi-Florida Islands. - The initial landing in the Florida group of islands as made in August 1942. Combat did not last long, but small groups of troops were widely scattered and had inadequate antimalaria supplies. A Navy malaria controlgroup began its activities late in 1942. Before this time, no malaria ratesfor all troops were available, although in one organization of 237 men themalaria rate was 2,004 per 1,000 per annum in December 1942, when the menwere supposedly taking 0.4 gm. Atabrine a week.
The highest total rate for this small group of bases was 593 per 1,000 per annum in May 1943 (table 62). Most of the cases were in a few units in poorly controlled areas.Atabrine suppression therapy was discontinued in about one-half the troopsin August 1943; it was discontinued in all troops in September 1944. At thistime, the total malaria rate was 58, and the original admission rate, 16per 1,000 per annum (table 63). Effective mosquito control work played themajor part in reducing the malaria rate on these small bases. It was madedifficult and complex by their scattered situation.
Russell Islands . - Unopposed landings were made on the Russell Islands in late February 1943, and a base malaria control unit arrived on March 3. There were neither natives nor Japanese on Banika or Pavuvu, the two main islands occupied. Mosquitobreeding sites were numerous; hundreds of ponds about 30 feet in diameterwere present in the coconut plantations.
The 43d Division, which made the initial landings, had been seeded with malaria on Guadalcanal, as had many of the troops which arrived later. Antimalaria details were establishedin all units of the 43d Division and in the Navy and Marine units withina month of occupation. A small staff of malaria control personnel was ableto effect a very considerable degree of control under conditions which werefavorable to the development of epidemic malaria. The malaria rate for Marchwas 281 per 1,000 per annum, most cases being caused by P. falciparum.Suppressive Atabrine therapy was given at the rate of 0.4 gm. per week,a dosage later found to be inadequate; supervision was unsatisfactory. Asa consequence, malaria rates of 200 to 400 per 1,000 per annum continued throughSeptember. However, unseeded units which came to these islands did not developthese high rates.
New Georgia Group . - The 43d Division attacked Rendova Island in the New Georgia Group on1 July 1943 and assaulted Munda in mid-July; the 37th and 25th Divisionsjoined it later. During the first 2 months, heavy combat caused the formationof many shellholes, bomb craters, foxholes, nits, and other sources of mosquitobreeding. The seedbed consisted of Japanese and already infected Allied troops.The Allied troops were presumably taking
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0.4 gm. suppressive Atabrine weekly, but its administration was poorly supervised. Anopheline breeding rapidly became a serious problem both on Rendova and New Georgia.
A malaria control team consisting of an Army malariologist, a Navy parasitologist, and several corpsmen landed on Rendova on 11 July and moved to Munda in August. This groupearly initiated a control program on Rendova which kept mosquito breedingat low levels and then vigorously attacked anopheline breeding areas in themain occupied areas of New Georgia. This was the first attempt to controlmalaria under combat conditions in the South Pacific Area and demonstratedthat a small group of trained personnel with simple equipment could accomplishmuch valuable work. It was a new concept in malaria control and was the basisfor the subsequent assignment of survey and control personnel to all largecombat units.
The malaria rate reached a peak of 629 per 1,000 per annum in September 1943; much of this was due to relapses in the heavily seeded 25th Division which had a rate above1,000 per 1,000 per annum at this time. By December, most of the heavilyseeded units had left the base, and the rate was 258 per 1,000 per annum.By May 1944, it had dropped to 51 per 1,000 per annum.
Vella Lavella . - Vella Lavella was invaded on 15 August 1943 by the 3d New Zealand Division and a small American force. It was secured on 9 October. A malaria control unit consisting of 4 officers and 33 enlisted men arrived with the division, and a Navy control group was also present. Most of the malaria cases occurred in a Marine defense battalion which had been heavily seeded on Efate in 1942.The rate in this battalion was 964 per 1,000 per annum in April 1944; atthe same time, the island rate was 329 per 1,000 per annum (table 63). Themethod of administration of suppressive Atabrine in this battalion was improved;in May its malaria rate had fallen to 114, while the island rate was 54 per1,000 per annum. The continuing low rates in the previously unseeded NewZealand division are a tribute to its malaria discipline and effective larvicidingprogram.
Bougainville . - The landing was made at Empress Augusta Bay, an almost uninhabited area,in November 1943. Malaria control groups accompanied the 3d Marine, Americal,and 37th Divisions. A base malaria control group was established in January1944. Because there were extensive swamps near the beach, the troop areawas established at some distance from the beach, where the underlying sandysoil proved easy to drain. Control work was started early, and the malariarate never became high. A peak rate of 119 per 1,000 per annum was recordedin January 1944 (table 63). Even though many of the troops were already seeded,0.6 gm. weekly of suppressive Atabrine helped keep the rate low. Aerosolbombs were available and were widely used.
Minor outbreaks ofmalaria occurred in troops on perimeter defense and in those making sortiesinto enemy territory. Most of these cases were due to P. falciparum. while most of those in the controlled area were relapses due to P. vivax.
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Emirau Island. -An unopposed landing was made on this small island in March 1944. Amalaria control group accompanied the troops and began a very effective mosquito control program immediately. Even heavy equipment drainage of all swamps wascompleted in 3 months. The 220 natives who lived in Emirau were moved toanother island.
The malaria experience of some of the Army units is of particular interest, since their personnel did not change so much as did those on the various islands.
Americal Division . - This division moved to Gaudalcanal by echelons in October, November, and December 1942. The troops lived and fought in highly epidemic areas. Therewas very little malaria discipline, no repellents or Aerosol bombs, and,although 0.4 gm. Atabrine weekly was prescribed, it is doubtful if it wastaken very carefully. The monthly malaria rate ran as high as 1,358 per 1,000per annum, while the division was on Guadalcanal.
In March 1943, thedivision was moved to Fiji, a nonmalarious island, for rehabilitation. Theentire division was treated with Atabrine and Plasmochin between April andJune. Thereafter, no antimalarial drugs were administered except to personswith clinical malaria. The malaria rate rose promptly to a high of 3,760per 1,000 per annum in August; it was still 2,880 per 1,000 per annum inOctober. The division was alerted for combat in November, and suppressiveAtabrine therapy was given at the rate of 0.4 gm. per week. This was increasedin December to 0.6 gm. per week. By January, the malaria rate had fallento 43 per 1,000 per annum. After 5 months of combat on Bougainville, thetotal rate for May 1944 was only 112 per 1,000 per annum. More details onmalaria in this division are given by Tumulty and coworkers.11 The malaria experience of this division is shown in chart 20.
Plasmodium falciparumcaused more than one-half of all malaria cases reported on Guadalcanalduring January, February, and March 1943, and P. vivax caused about25 percent of the cases. Plasmodium falciparum continued to predominatefor a few weeks after the division arrived on Fiji, but P. vivax rapidlycame to the fore and caused practically all the subsequent cases.
Suppressive Atabrine therapy was discontinued on Fiji in the hope of demalarializing the division. The theory was that if the troops were allowed to have their malaria, they would get it out of their systems and become free of it. The experience withthis and other units showed that this would not take place within a reasonablelength of time but that repeated relapses would occur.
147th Infantry . - This regiment landed on Guadalcanal in November 1942 and February 1943, and took part in combat. The regiment was on 0.4 gm. weekly suppressive Atabrine,but its administration was not closely supervised. While most of the diagnoseswere not confirmed by blood smear examination,
11 Tumulty, P. A., Nichols, E., Singewald, M. L., and Lidz, F.: An Investigation of theEffects of Recurrent Malaria; an Organic and psychological Analysis of 50Soldiers. Medicine 25: 17-25, February 1946.
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CHART 21.- Incidence of malaria in the 147th Infantry, December 1942to October 1944, inclusive
the regiment's sick reports showed malariain 48 percent of the men, and the malaria rate reached a peak of 1,558 per1,000 per annum in April 1943.
In May 1943, the regiment was sent to British Samoa, a nonmalarious island, and demalarialization was begun. Downs 12 described the malaria history of this regiment in detail. The regiment was divided into four groups. One received Atabrine mass therapy at once; the second received Atabrine mass therapy after a 10-dayperiod without medication; the third received mass therapy with Atabrineand Plasmochin; and the fourth received no mass therapy. Suppressive treatmentwas then discontinued, although clinical cases were treated as they occurred.
There was no relationship between the treatments and the incidence of malaria in the four groups. Becausethe termination of mass therapy was staggered, the peak malaria rate of theregiment did not exceed 4,090 per 1,000 per annum, although peak rates indifferent groups exceeded 14,000 per
12 Downs, W. G.: Results in an Infantry Regiment of Several Plans of Treatment for VivaxMalaria. Am. J. Trop. Med. 26: 67-86, January 1946.
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CHART 21.- Incidence of malaria in the 147th Infantry, December 1942 to October 1944, inclusive
1,000 per annum. The rate continued high until suppressive Atabrine therapy was begun again in December 1943. In January 1944, the rate had dropped to 334 per 1,000 per annum, and it continuedto decline thereafter (chart 21).
An even more marked reversal than in the Americal Division of species predominance from P. falciparum to P. vivax occurred in this regiment after it left Guadalcanal.
25th Division . - This division landed on Gaudalcanal in late December 1942 and fought through the latter part of the campaign. It soon became heavily infected; in April 1943, the malaria rate reached a peak of 2,335 per 1,000 per annum, although the division was presumably receiving 0.4 gm. per week suppressive Atabrine. The division took part in the New Georgia and Vella Lavella campaigns from July to October. In October 1943, its malaria rate was 1,550 per 1,000 per annum. In December, the division was sent to New Zealand and later toNew Caledonia, both nonmalarious islands. Suppressive Atabrine therapy wasdiscontinued in a small group to learn how heavily the division was seeded.In 4 weeks, the rate in this group was 2,091 per 1,000 per annum. Becauseof the experience already described, no attempt was made to demalarialize this division. Atabrine administration was improved, and the malaria rate declined progressively to 44 per 1,000 per annum in October 1944 (chart 22).
37th Division . - The division arrived on Guadalcanal in March 1943 and was bivouacked in a relatively well controlled area. It. at once instituted an
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CHART 22.- Incidence of malaria in the 25th Division, January 1943 to October 1944,inclusive
effective larviciding program and enforcedthe use of individual malaria discipline. Suppressive Atabrine therapy wasadministered by roster, 0.4 gm, per week being given until October 1943,and 0.6 gm. per week thereafter. The division took part in the New Georgiacampaign, from July to September 1943, and then returned to Guadalcanal.It was sent to Bougainville in November 1943, where it took part in limitedcombat for nearly a year.
The malaria rate remained low in this division, never exceeding 250 per 1,000 per annum, andusually being much below this figure. This was partly because the division was bivouacked in a relatively well controlled area when it first came toGuadalcanal, partly because of its early recognition of the malaria hazard,and finally to the energetic and thorough control program that it carriedout.
43d Division . - This division bivouacked on Guadalcanal in February 1943 while en route to the Russell Islands and New Georgia. It remained on the latter islands until December 1943, when it was transferred to nonmalarious New Zealand. Throughout its service on the malarious islands, the division had been kepton suppressive Atabrine therapy. During February and March 1944, a smallgroup was taken off Atabrine to learn how heavily the division was seeded.The malaria rate in one company rose to 2,025 per 1,000 per annum, approximatelyone-half the peak rate of the Americal Division. The monthly malaria rateof the remainder of the division did not exceed 235
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per 1,000 per annum and by July 1944 had dropped to 64 per 1,000 per annum. During all this time, the division was receiving 0.6 gm. Atabrine per week.
Plasmodium species in troops. - P.malariae was rare among troops in the South Pacific, almost all thecases being due to P. falciparum or P. vivax. The predominantspecies changed with the progress of each campaign. Early in the campaign, falciparum malaria predominated, but, as control measures progressedand the general malaria rate declined, vivax malaria became increasinglycommon, until at length it far outweighed falciparum malaria.
This sequence ofevents is well illustrated by the experience on Guadalcanal. In January 1943,there were twice as many cases of falciparum as of vivax malaria; the two species were about equally common in July, while in January 1944 therewere 20 times as many vivax as falciparum cases. The totalmalaria rates per 1,000 per annum for the island decreased coincidentally from 1,169 in January 1943 to 608 in July 1943 (table 62) and to 200 in January1944 (table 63). Several factors were responsible for this change. In January1943, a condition of hyperendemicity existed, with a high transmission rate.Many of the cases recorded as falciparum were probably mixed vivax-falciparuminfections in which the vivax had been temporarily suppressed.During this period, too, almost all malaria cases were primary ones, whilelater on an increasing percentage of them were relapses. Since relapses occurmore frequently in infections of vivax malaria, than in falciparum,the proportion of vivax cases increased steadily. The infectedtroops formed the seedbed for new infections, and as the species distributionof the seedbed shifted, so did the species distribution of new infections.As a result, the percentage of vivax cases increased progressively.In addition, as the overall incidence of malaria decreased, double infectionsbecame less common, so that falciparum malaria no longer masked thevivax form. Improvement in Atabrine discipline also decreased theincidence of falciparum malaria.
Prevalence and Decline of Malaria
High malaria rates occurred in the early landings because the importance of malaria was not properlyassessed by the troop commanders until it had incapacitated many men andhad interfered seriously with the efficiency of their activities. No attemptwas made at first to carry out individual protective measures, to enforcesuppressive medication, or to combat mosquitoes. In addition, the proximityof infected natives or Japanese provided a seedbed of the disease, and thecombat-produced shellholes, foxholes, and ruts greatly increased the mosquitobreeding areas. When the importance of malaria was once recognized, eliminationof mosquito breeding places, larviciding, enforced use of suppressive Atabrineand of individual protective measures, elimination of infected Japanese,and removal of infected natives all helped to control the disease. The mostimportant of these measures was the elimination of anopheline mosquitoes.While Atabrine undoubtedly prevented the clinical
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appearance of falciparum malaria in many thousands of troops, it merely postponed the inevitable clinical attackof vivax malaria.
Malaria in Enemy Troops
Data on the prevalence of malaria in South Pacific natives have already been given (table 59).
The Japanese suffered more severely from malaria than did the Allied troops. They apparently carriedout little mosquito control in the Solomons, although a few knapsack sprayersand small quantities of larvicidal oils were captured. They also had bednets, a repellent cream whose active ingredient was oil of citronella, amosquito-repelling punk, quinine, and Atabrine.
Captured medical reports quoted by Harper, Lisansky, and Sasse 13 stated that amongthe Japanese forces in the Solomon Islands and Bismarck Archipelago the primarymalaria rates per 1,000 per annum were 450 in December 1942, 1,098 in January,and 1,637 in February 1943. At Rabaul, New Britain, 32.4 percent of one unitand 22.09 percent of another were malaria patients during February 1943.The total malaria rate for Rabaul and vicinity was 2,503 per 1,000 per annumin April 1943.
The few prisoners captured in the South Pacific were usually emaciated and almost invariably malarious.
ANTIMALARIA POLICY AND ORGANIZATION
At Theater Level
The South Pacific Force under Navy command was a joint U.S. Army, Navy, Marine, and New Zealand group. Commander, South Pacific, was the senior Navy command. The senior Armycommand within the area was U.S. Army Forces in the South Pacific Area. Islandcommanders were responsible to ComSoPac and to Commanding General, USAFISPA.On each base, there was an army service command and a naval headquarters,each responsible to the island commander. Commanding generals of divisions,if on established bases, were responsible to island commanders on matterspertinent to that base.
Development of area organization
The initial malaria epidemic among Allied troops occurred on Efate which was occupied in March 1942. During the following month, the military forces on this island experienced a malaria rate of 2,678 per 1,000 per annum (table 61). This explosive outbreakof malaria caused great concern, and an experienced Navy medical officer,Commander Sapero, was sent to Efate in July 1942 to take charge of malariacontrol measures. An organization had to be created
13 Harper, P. A., Lisansky, E. T., and Sasse, B. E.: Malaria and Other Insect-Borne Diseasesin the South Pacific Campaign, 1942-1945; I. General Aspects and ControlMeasures. Am. J. Trop. Med. 27 (suppl.) : 1-67. May 1947.
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from the ground up; personnel had tobe secured, trained, and assigned, directives issued, and supplies obtained.
This organization developed slowly. It required time to procure and train personnel in the problemsof entomology, engineering, and malariology peculiar to this area. Only afterfield trial was it possible to develop a staff for area headquarters andto make those transfers which were essential to build a strong organization. The directives which formed the legal basis of this organization and which established malaria control policy were written and rewritten as new problems were encountered over a period of more than 2 years. The first directive, ComSoPac Serial 301e, was issued on 2 September 1942 and called attention to the existence of a "malaria control unit" available for use on the three bases then occupied, Efate, Espíritu Santo, and Guadalcanal. A group of 10 persons was sent to Espíritu Santo in September 1942 to set upthe base malaria control unit there.
Despite the fact that anopheline populations on Guadalcanal were increasing and that malaria was beginning to appear, no malaria control personnel was allowed to start work on that island until mid-November, when the malaria epidemic was in fullswing and the anopheline breeding had reached a high level. Such an attitudetoward malaria control measures was typical of the prevailing opinion thatmalaria and malaria control were of minor importance during combat operations.This attitude was largely due to ignorance of the damage that uncontrolledmalaria could do to military personnel. The difficulties in establishingmalaria control on Guadalcanal despite the obvious need made it increasinglyevident that a stronger area directive was necessary. Such a directive, ComSoPacSerial 0094b, was issued on 13 November 1942 and is quoted in part:
Malaria control units,with headquarters at Base Roses (Efate), have been and are being establishedat various bases in the South Pacific Area. Each unit consists of a medicalofficer in charge, an entomologist, and laboratory and field technicianswho are specialists in problems of malaria control. These units will adviseand render service in connection with malaria control to U.S. Army, Navy,and Marine Corps Units and Allied Forces occupying malaria infested islands.
It is the responsibility of the Malaria Control Units to: (1) make epidemiological studies pertaining to malaria, (2) operate laboratories for diagnosis, (3) train personnel fromother organizations in laboratory procedures pertaining to malaria control,(4) advise in regard to mosquito control measures, (5) advise in regard todisinsectization of aircraft, (6) make such recommendations to the properauthorities in regard to malaria control as the circumstances require, (7)procure, store and distribute antimalarial drugs for chemoprophylaxis asmay be required by the forces at each base.
A laboratory section of a Malaria Control Unit will be established at certain nonmalarious bases. The officers in charge of these units will carry on studies of malaria infectedpersonnel evacuated from malarious bases and will make recommendations withrespect to treatment of and malaria control measures pertaining to evacuatedpersonnel. They will also undertake training of laboratory and medical fieldtechnicians attached to organizations preparing to enter malarious basesin the special procedures applicable to malaria control.
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Personnel of Malaria Control Units will be attached to the major medical department activity ofthe base to which the unit is assigned for administrative purposes, berthingand subsistence. The major medical department activity will also providelaboratory facilities for these units.
The Commanders ofall bases in which Malaria Control Units are established are enjoined tocooperate to the fullest extent with the officer in charge of Malaria ControlUnits in order that those units may accomplish their extremely importantmission. It is directed that officers in charge of malaria control unitsbe consulted in connection with the selection of sites for camps and airfieldsand that their recommendations in such matters be given due consideration.
The last sentence of this quotation gave the malaria control personnel on each base a voice in and a responsibility for the location of campsites and other facilities. The malariologists, entomologists, and sanitary engineers made surveys andgave valuable advice concerning the selection of sites which were or couldbe made relatively malaria free and to the avoidance of highly malarious areas.
A year later this and other orders governing malaria control operations were consolidated greatlystrengthening control efforts. Responsibility for the control of insect-bornediseases in all forces was now clearly fixed on one officer with a headquartersunit of mixed Army and Navy personnel. The provision that this officer shouldrecommend "the establishment of Malaria Control Units at bases, and the administrationand coordination of malaria and epidemic control" was translated in practiceinto responsibility to recommend the assignment and reassignment of all malariacontrol personnel in the area. Similar centralization of responsibility forantimalaria activities on each base was provided by the provision that thesenior malariologist at each base should make recommendations and reportdirectly to island commanders. This centralization of responsibility followeda year after the height of the epidemic of malaria on Guadalcanal and ata time when repeated malaria relapses were seriously delaying the returnto combat of such combat troops as the Americal Division and the 147th Infantry(charts 20 and 21). Excerpts from ComSoPac Serial 002263, dated 24 September1943, are as follows:
Organization and Responsibilities
a. Pertaining tothe area program of control. A Malaria and Epidemic Control Officer on theStaff of Commander South Pacific has cognizance of all matters pertaining to the control of malaria in all forces in the area. He makes recommendations to the Commander South Pacific for the overall area program of control andrecommendations for the establishment of Malaria Control Units at bases, andthe administration and coordination of malaria and epidemic control.
An Area Entomologist and an Area Engineer serve to coordinate efforts in their special fields. A Training and Education Officer is responsible for an educational program of practical measures of malaria prevention for all shore-based forces inthe Area. He prepares such educational material as malaria training manualsfor line and medical officers, and for enlisted men. Posters, films, andother useful training aids are distributed.
b. Pertaining tothe control program at malarious bases. The senior Malaria and Epidemic ControlOfficer of base units is directly responsible to the Island Command for
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an effective program of control, applicableto all forces at the base. He formulates the control program for the baseand makes recommendations to the Island Commanders who in turn will requiresubordinate units to carry out prescribed control measures within their respectivecommands.
Reports of the seniorbase Malaria and Epidemic Control Officer are submitted directly to the IslandCommander. Copies of such of these as are pertinent are forwarded directlyto the senior subordinate commands of the various services at each base,to the Force Medical Officer, Commander South Pacific, the Surgeon, USAFISPA,and Headquarters, Malaria and Epidemic Control.
Base Malaria Control Units are permanently established and serve all forces without service distinction.The units are jointly constituted, being composed of specially trained Armyand Navy personnel--malariologists, entomologists, engineers, parasitologists,and laboratory and field enlisted technicians.
The Malaria Control Unit described in this directive, or Malaria Control Group as it was subsequently called, consisted of a malariologist, one or more Army malaria survey detachments, and one or more Army malaria control detachments, or equivalent Navy personnel. The command channels of this group are discussed later (p. 442).
The area organization developed as the area expanded to 11 malarious bases, as the legal basis wasbroadened, and as the personnel increased from 4 persons in July 1942 toover 750 technically trained personnel and nearly 4,000 laborers in June1944. This growth made clear the need for an area staff which was developedin the following order of appointment: An area malaria and insect controlofficer; an area entomologist; an Army liaison officer, an area trainingand education officer; an area administrative assistant; an assistant malariaand insect control officer; an area engineer and two filaria survey officers.
Responsibilities and duties
The duties and responsibilitiesof the area organization were as follows:
1. It served all Allied Forces in the area.
2. It formulated areadirectives which were issued by ComSoPac and Commanding General, USAFISPA, and which defined and gave authority to insect and rodent control policy, organization and function.
3. It made recommendations for the procurement, assignment, and transfer of all personnel assigned toinsect control activities.
4. It provided technicaland supervisory assistance to the various base and division malaria and insectcontrol groups.
5. It was responsible for the control work of the base groups and established a uniform system ofreports and inspections.
6. It recommended allowancesand provided for procurement and distribution of malaria control equipmentand supplies.
7. It provided an areawideeducational and publicity program of malaria and insect control for all personnel,and special information for line officers, medical officers, and for personnelassigned to malaria and control work.
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CHART 23.- Malaria and Insect Control Organization, South Pacific Area, 1 June1944
8. It made personnel and equipment available for special problems of malaria control such as airplaneapplication of DDT solutions and spraying of bed nets with DDT, and for problemsconcerned with filariasis, mite-borne typhus, dengue, and rodent control.
Chart 23 shows thepersonnel of the area organization and the distribution of base and divisiongroups. Letter orders authorizing all necessary travel to malarious baseswere given to the area staff. Some member of the headquarters staff madea complete circuit of the malarious bases every 4 to 8 weeks to keep in touchwith local work and needs. The area entomologist and engineer offered technicalassistance and advice to the corresponding officers in each base unit. Distributionof technical information was also accomplished through a newsletter and throughspecial publications such as synoptic keys to mosquitoes. Uniform methodsof reporting information were adopted for all base reports as well as forarea reports.
Procurement andassignment of technically trained personnel. - Table 65 describes the personnel engaged in insect control work as of 15 May 1944. The technically trained personnel comprised medical officers, entomologists, parasitologists, sanitary engineers, and enlisted personnel of the control and survey detachments. They formed the Base and Division Malariaand Insect Control Groups. As of 15 May 1944, this personnel comprised 128officers and 643 enlisted men, divided as follows: Army, 452; Navy and Marine,282; New Zealand, 37.
Technically trained Army malaria control personnel was provided by the War Department in three categories: Malariologists (medical officers), malaria survey detachments, and malaria control detachments.
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TABLE 65.-Malaria and insect control personnel, South Pacific Area, 15 May 1944
Army malariologists arrived as casual officers. Almost all of these officers had taken the coursein tropical medicine at the Army Medical School, and the majority had hadfield work at the Army school in Florida or Panama. They were attached toHeadquarters, Services of Supply, South Pacific Area, and then ordered ondetached service to the various bases and divisions. There were 21 Army malariologistsin the area: 2 lieutenant colonels, 8 majors, and 11 captains. One Army malariologistwas on the area malaria control staff, 6 were senior base malariologists,6 were division malariologists, 1 was assigned to the Office of the ChiefSurgeon, USAFISPA, 1 to Headquarters, XIV Corps, and the remainder actedas assistant base malariologists.
There were 17 malariasurvey detachments and 20 malaria control detachments within the area, asof 1 June 1944. The officers of these detachments all met the basic technicalrequirements for their specialty. The enlisted men were untrained at timeof assignment but were usually of high caliber and rapidly became competenttechnicians under the guidance of their officers. There would be great advantagesif in the future these enlisted men could have a period of formal trainingat Army medical centers or at one of the Army malaria control schools.
Navy malaria control personnel was procured through the Navy Department either from the Malariology School of the Naval Medical School, Bethesda, Md., or from Navy replacement pools or other organizations within time South Pacific. The usual Navy malariacontrol team consisted of one officer, an entomologist, and from three tofive enlisted men. Each Marine division
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was provided with a larger team (called an epidemiology unit) of 3 officers (malariologist, entomologist, parasitologist) and 12 enlisted men. An engineer for this team was provided from the sanitary section of the naval construction battalion which was attached to each Marinedivision. Enlisted men from Bethesda were well trained in laboratory diagnosisand in elementary field procedure. Several Navy officers experienced in rodentcontrol were obtained from organizations in the South Pacific. Navy warrantand Hospital Corps officers were also secured locally to administer malariacontrol personnel and supplies on larger bases.
The Navy malariology teams were often broken up and assigned to Army-Navy or all Navy groups tomeet the needs of a local or island situation. This was in contrast to thepolicy of assigning Army units intact and resulted in a valuable flexibility.
Procurement oflabor and equipment. - Skilled and semiskilled labor was needed for semipermanentmosquito control work which required the operation of heavy equipment suchas bulldozers and draglines and special skills such as those of a dynamiteexpert. Almost all such skilled labor and heavy equipment were obtained fromnaval construction battalions or from the Army Corps of Engineers.
An entire naval constructionbattalion was assigned to malaria control work on Guadalcanal in May 1943on recommendation of the theater malariologist. Subsequently, sanitary sectionsfor malaria control work were organized in all naval construction battalions.
Unskilled labor wasrecruited from three sources: Army medical sanitary companies, natives, andtroop unit antimalaria details. The first Army medical sanitary company arrivedabout mid-1943 and was assigned to Guadalcanal. Subsequently, nine such companiesarrived of which eight were assigned to malarious islands on recommendationof the theater malaria and insect control headquarters. It should be emphasizedthat every medical sanitary company on a malarious island in the South Pacificworked full time at malaria control. Credit for withstanding the pressureto assign these units to other work must be given to the Surgeon, USAFISPA.
Native labor was scarce and was strenuously competed for by both combat and service units. Usually a certain proportion were assigned by the Island Command headquarters to malaria control work.
The work of skilled and unskilled labor is described on pages 445 and 487.
Supplies and equipment . - There were acute shortages of all antimalaria supplies and equipmentin 1942, of which the most important were Atabrine, mosquito repellent, insecticideand knapsack sprayers. In this early period, the area malaria control organizationadvised on allowances and was responsible for the establishment of quotasand distribution of those items in which shortages were acute. Excerpts fromthe pertinent directive14 follow:
14 Circular Letter No. 15, Headquarters, Services of Supply, South Pacific Area, 13 May1943.
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1. Central procurement, distribution and issue of insecticides, pest control supplies and equipment for all Armed Forces located in the South Pacific Area (less those located in the Samoan Group) has been assigned to the Army Services of Supply by ComSoPac.
2. Service Command Quartermasters,* * * in cooperation with the Base Malaria ControlOfficers, will receive, store, and distribute the above supplies to all ArmedForces at each base. Navy Supply Officers, Marine Quartermasters and NewZealand Supply Officers may obtain their stocks in bulk from Base or ServiceCommand Quartermasters at each Base, by requisition.
* * * * * *
5. The use of insecticidesand insect repellents within the South Pacific Area will be governed by Instructionsissued by each base malaria, control officer.
Transportation wasoften a serious problem. Each malaria control group was responsible for aterritorial coverage which averaged about 20 square miles, often in the shapeof a long narrow beachhead. In addition to distributing their own surveyand control crews to all parts of this territory, most groups transported50 to 100 native laborers to and from work each day and hauled labor details.They also did power spraying, hauled gravel, and did other work requiringvehicles. The increased number of vehicles which were finally authorizedfor malaria detachments and for medical sanitary companies were adequate.A special theater directive provided transportation for malariologists.
Liaison
Since this was ajoint service organization, no liaison was needed between branches of militaryservice or with Allied Forces. There were contacts with the civil populationon New Caledonia and on Efate chiefly in connection with antimosquito operations.These were ordinarily easily handled through official channels. The assistanceof the parish priest was sought, and generously given, when dengue carryingmosquitoes were found breeding in flowerpots and other receptacles used fordecorating graves in the cemetery.
Local or Island Organizationand Procedure
The work of the malariologist
The command basis for the work of the island malariologist has been described (pp. 435, 436). By these directives, the senior malariologist at each base eventually was made directly responsible to the island commander for formulation of a programof control applicable to all forces--Army, Navy, Marine, and Allied--and forrecommendations to make this program effective. The commanding officer ofeach subordinate organization on the island was responsible for all malariacontrol activities within amid adjacent to this bivouac site. Reports andrecommendations of the senior base malariologist were submitted directly tothe island commander, who, in turn, required the subordinate commanders tocarry out prescribed control measures. This chain of command was unusual inthat it did not conform with the ordinary channels through the
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CHART 24.- Island organization and command channels, Joint Army-Navy malaria and insectcontrol
commanding officer of service command or through the Commander, Naval Advanced Base.
This latter point may be expanded by citing the problem of Guadalcanal where the malaria controlorganization was a mixed one of Army and Navy personnel and where the firstisland malariologist was a Navy officer, subsequent ones being Army officers.The question arose: Should command channels through Commander, Naval AdvancedBase, be utilized when the senior malariologist was a Navy officer and shouldthese channels be changed to go through Commanding Officer, Service Command,when the senior malariologist was an Army officer, or should both commandchannels be utilized since this was a mixed service group? The solution wasdirect reporting to the Island Command with copies to subordinate commands.
The organization of the Army-Navy malaria control personnel on a typical island base is shownin chart 24. A mixed Army-Navy group was developed on most islands. The variablesize of the Navy units was particularly advantageous for small bases whereonly one or two officers and a few enlisted men were needed and where theArmy units of fixed size were too large.
Chart 25, Guadalcanal Malaria and Insect Control Organization, is presented as an example of organizationaldevelopment on islands large enough to require two or more malaria controlgroups. (The term "Malaria Control Group" is used to designate a workingorganization comprising a malariologist,
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CHART 25.-Guadalcanal Malaria and Insect Control Organization
a malaria survey detachment, and amalaria control detachment.) The Island headquarters was not provided forby any table of organization but developed to fill a need for overall supervisionon larger bases. Modifications of the headquarters section, diagrammed inchart 25, were established on Efate, Espíritu Santo, New Georgia,and Bougainville.
The malaria control personnel on most bases formed a joint Army-Navy group who lived under oneroof and worked together in one area. Two-thirds of the groups were attachedto Army or Navy hospitals for quarters and rations, one-third to Navy advancedbases or Army service commands. Three groups set up independent housekeepingwith a medical sanitary company assigned to malaria control work. This haddistinct advantages, among which was a time for meals favorable for fieldwork.
The position of themalariologist in this organization was an ambiguous one which can be explainedbest by saying that he was a staff officer whose duties often required theassumption of command responsibility. This was evident in his relations withassistant malariologists and with personnel of survey detachments, controldetachments, and sanitary companies. He selected their locations, directedtheir work, and initiated or approved recommendations for promotion. Thisassumption of command responsibility functioned well because of a generalwillingness to cooperate and because the high command fostered such a situationby directives quoted previously which made the ma-
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lariologist responsible for all insect control activities on a base. However, the malariologist had no legal command authority over the malaria detachments and medical sanitary companies which were small, independent commands. In a long-range program, this officer shouldhave command authority corresponding to his responsibility.
The duties of themalariologist included:
1. Formulation of aneffective program of mosquito control, utilizing the advice and assistance of specialists, the entomologist, the parasitologists, and the engineer.
2. Integration of thework of the survey detachment, the control detachment, and labor.
3. Estimation of needfor and requisition of personnel and supplies to execute the program.
4. Development of aneffective malaria training and educational program.
5. Preparation of directivespertaining to malaria discipline and the making of spot inspections for violationsof malaria discipline.
6. Consultation andrecommendation in regard to the selection of sites, for camps, airfields, bivouac and maneuver areas.
7. Segregation of natives.
8. Recommendations concernedwith the institution and discontinuance of suppressive medication.
9. Supervision of disinsectizationof airplanes and ships and other measures to prevent the dissemination ofdisease.
10. Preparation ofreports of the malaria situation on his base or in his division area, includingespecially statistics regarding malaria incidence, status of malaria discipline,entomological and climatological data, work of control units, activitiesof the training program, status of antimalaria supplies and of personnelengaged in control work, and recommendations.
The first work wasdone where troops were concentrated. Speed in instituting control measures was most important in occupying a new base. Initial surveys were done rapidly and more thorough work came later. Larviciding and other temporary work, suchas clearing of paths to facilitate oiling, were usually initiated coincidentallywith the first survey.
The initiation ofsemipermanent work depended on the size of the troop population to be protected,the period the area was to be occupied, and the available labor and equipment.As soon as surveys were completed, a list was prepared of semipermanent controlprojects with detailed estimates of labor and equipment. These projects werelisted in order of priority and were initiated directly if they were withinthe scope of the malaria control personnel under the jurisdiction of themalariologist. Larger projects requiring special equipment and labor weresubmitted through proper channels to the commanding general for approvaland for assignment of the needed equipment and personnel. These projectscompeted with other high priority work, such
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as roadbuilding, airfield construction, and erection of hospitals. Presentation had to be clear and concise and hadto include an adequate justification for priority.
The need for continuous integration of the work of the survey and of the control units was recognized rapidly. In wartime practice, survey and control work were initiated simultaneously and continued to be interdependent.
The malaria survey and the malaria control detachments
The Army malaria survey detachment consisted of 2 officers and 11 enlisted men, all technically skilled, and charged with entomologic and parasitologic work to aid the controlof malaria and all other insect-borne disease.
The entomologist and his enlisted men furnished information about the breeding of mosquitoes and other insects, their biology, and relations to disease. This information was always accompanied by recommendations as to specific control measures. The work was continuous and was recorded on maps and other forms so as togive a clear and continuous check on the effectiveness of control.
The parasitologic section of the survey unit furnished information about the incidence of malariaand other parasites in natives, in U.S. troops, and in Japanese prisonersand recorded this knowledge so as to aid both the planning and the evaluationof control work.
The Army control detachment comprised an engineer and 11 enlisted men and was responsible forplanning, executing, and maintaining all insect control measures based onthe findings of the survey detachment; for supervision and correlation ofall labor and equipment for this work; and for maintenance of suitable recordsto give a continuous and clear picture of control activities.
The enlisted personnel performed a variety of duties, according to the local situation. These menwere most economically and efficiently employed as supervisors. Occasionally, on large bases, an entire control team was made responsible for a special project such as work on flume and culvert maintenance. Additional enlisted personnel were assigned to work with dynamite or bangalore torpedo ditching crews. Men were trained to operate bulldozers, draglines, and other heavy equipment. On islands where airplane spraying of DDT solutions became an importantcontrol measure, crews of one to six men were assigned to mix DDT solutionsand to service the spray apparatus installed in the planes.
Table 66 shows theaverage number of personnel available for the work of the malaria control units during the 6-month period from December 1943 to June 1944. The engineer was responsible for the work of these laborers except that of the troop antimalariadetails. Thus, on the larger bases, each engineer had from 100 to 250 men,exclusive of troop units, working under his general supervision.
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TABLE 66.- Personnel available for work of malaria control units, South PacificArea 1
Troop Unit Antimalaria Organization
From the first, antimalariadetails were expected to do the larvicidal work in their own areas. The assignmentof men to oiling details in 1942 and the early half of 1943 was irregularand depended on personal arrangements between the island malariologist andeach commander. In September 1943, an areawide directive, ComSoPac Serial01619, dated 13 September 1943, ordered the formation of a mosquito controlsquad in every battalion. A subsequent directive, ComSoPac Serial 02158,dated 19 October 1944, ordered the formation of an antimalaria detail ineach company, battery or similar unit. This detail consisted of one noncommissionedofficer and two enlisted men per infantry company or a proportionate numberfor other units. In nonmedical units, these details were made up of nonmedicalpersonnel. These details were responsible for all insect control work withinthe region occupied by their units, and their work was checked by techniciansfrom the base or division malaria survey detachment described previously.
These antimalaria details worked effectively in all situations except those of frontline combat.It was not only impossible for most antimalaria details to do antimosquito work under combat conditions, but these personnel were as fatigued as their comrades at the end of the combat period and so further postponed this work.To remedy this situation, temporary spray teams were formed in combat regimentsand are described in the next section.
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Division Malaria and Insect Control Organization
The Division Malaria and Insect Control Group comprised the division malariologist, a malaria surveydetachment, and a malaria control detachment totaling 4 officers and 22 technicallytrained enlisted men. This group was attached to the division over and aboveits established allowance for Medical Department personnel. They performedthe same functions for the division as did the base malaria and insect controlgroup for each island base, with the additional duty of providing antimalariaprotection during the periods of active combat. This resulted in less emphasison specialization and more emphasis on flexibility, with every man trainedto aid in all phases of a simple anti-mosquito program.
It was the duty ofthe division malariologist to provide plans for the control of malaria, dengue,mite-borne typhus, and other insect-borne diseases during a period of activeoperation. The final plan, selected from several prepared in advance, wasdetermined by the particular military situation.
An important feature of all such plans was the provision for a pool of trained men to do temporary insect control work behind the lines during combat periods. This pool of personnelwas obtained by drawing one man from each antimalaria detail and adding atechnically trained nucleus from the attached survey and control detachments.In most plans, this personnel was split into four temporary spray teams,of which one was attached to division headquarters and one to each of thethree regimental headquarters. The temporary spray team went ashore withthe division or regimental headquarters to which it was attached and beganwork. Fly control was done by spraying unburied bodies with 5-percent DDTsolution or 1-percent sodium arsenite solution. Straddle trenches, pit latrines,and other sources of fly breeding were treated similarly. Mosquito controlmeasures were carried out around headquarters, medical facilities, supplydumps, and along communication lines, (See appendix A, p. 582.)
Malaria Control Labor
Unskilled labor wasobtained from Army medical sanitary companies and natives. Each Army medicalsanitary company consisted of 3 officers and 109 enlisted personnel. Thesecompanies provided their own messing facilities and were authorized 15 to operate nine vehicles and other suitable equipment. They were assignedto island commands and were employed as directed by the malariologist inconjunction with antimalaria work. There were eight medical sanitary companiesused only for malaria control within the South Pacific Area as of 1 June1944, located as follows: Four companies on Guadalcanal; one each on RussellIslands, Munda, and Bougainville; and one divided company
15 T/O&E 8-117, Medical Sanitary company. 13 May 1944.
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with a platoon on Green Island and aplatoon on Emirau Island. They rapidly developed an understanding of theproblems of malaria control and facility in necessary procedures. Enlisted men who showed aptitude were trained in the operation and maintenance of heavyequipment, in dynamite work, and in mosquito survey work. These troops wereof great value as a constant source of experienced labor. Their activities included larviciding, application of residual spray, hand ditching, and similarwork.
Natives were employed on nearly all bases. The decision to utilize this source of labor was made early in the campaign with the knowledge that these local inhabitants constituted a potential seedbed of malaria and filariasis. The malaria control organization attempted to minimize this health hazard by segregation and by other means described in the section on malaria control measures. Laborers worked in sectionsof 25, each with its own native sergeant. The total number of imported Melanesianlaborers on all bases was over 6,000 in 1944. About 600, or 10 percent, workeddaily on malaria control during the period of maximum activity in the theater.
Airplane Spraying Arrangements
Arrangements made by the malaria and epidemic disease control organization for the accomplishment of airplane spraying varied on different bases. In one respect, however, theywere uniform; that is, all spraying was done on a scheduled basis and becauseof known need for larvicidal work, with the exception of spraying done ona purely experimental basis for evaluation of equipment. Only small aircraftwere routinely used. Frequently, the equipment used and operating arrangementsresulted from informal arrangements, and much of the spray equipment wasfabricated at airplane maintenance shops. On most bases, pilots were assignedto the malaria control organization for operational control, a most importantfactor in the accomplishment of efficient airplane spraying. The arrangementseventually worked out for airplane spraying on Guadalcanal may be consideredrepresentative of this work in the South Pacific.
All regularly scheduledand special flights were under the control of the Island Command entomologistwho briefed the pilot on the area to be covered and arranged for loadingthe airplane with insecticide. The pilot arranged for operational clearancefrom the field where the plane was based and from the field from which operationswere to be carried out. Usually, the field nearest the site to be sprayedwas selected for use, in order to minimize the time required for return tothe field for reloading. Frequently, abandoned airstrips were used untilthis practice was forbidden because of the lack of emergency equipment. Aircraftwere serviced by means of a mobile service truck developed and equipped forthe specific purpose. In practice, the use of aircraft without radio equipmentproved an advantage because of priority in landings and take-
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offs from busy fields. Experienced pilots,properly briefed, needed no ground guides other than terrain or vegetativefeatures in order to accomplish thorough coverage.
Other Military Agencies Engaged in Antimalaria Work
Skilled labor formalaria control work included dragline and bulldozer operators, dynamite experts,carpenters, and welders to make flumes and culverts. Such skilled personneland heavy equipment were obtained chiefly from naval construction battalionpersonnel, and in small part from the Army Corps of Engineers.
In May 1943, the need for large-scale mosquito control work on Guadalcanal became so urgent that the entire 63d Naval Construction Battalion was ordered by ComSoPac tomalaria control work at that base. The personnel of this battalion rapidly became acquainted with malaria control problems and techniques and accomplished an extraordinary amount of semipermanent control work over the entire base.
The formation ofsanitary sections in all naval construction battalions for use on malaria control work was authorized by a series of directives issued in July and August.These directives ordered each naval construction battalion to form a sanitarysection of 110 enlisted men and to provide specified equipment for work onmalaria and epidemic control projects under the direction of base and division(Marine) malariologists. Equipment assigned to each sanitary section includedone dragline crane, one tractor with bulldozer blade, and seven trucks. Sincethere were about 20 naval construction battalions on malarious bases in theyear subsequent to this order, these directives made available to malariacontrol a potential total force of over 2,000 men and more than 20 bulldozers,20 dragline cranes, and 140 vehicles. Actual compliance with these directivesfurnished about 500 men, 10 to 15 bulldozers, and 8 to 12 dragline cranesdaily for work on malaria control projects during the 8-month period, November1943 to June 1944.
Despite outstanding work by many of these battalions, compliance with these directives was usuallydelayed and incomplete. Work often was done too late to forestall an initialoutbreak of malaria and seeding of troops. This was due to high prioritiesfor airfields, roads, harbor, and storage facilities. Requests for diversionto malaria control of 10 percent of men and equipment often seemed unreasonableto the officers responsible for major construction projects.
Certain faults wereinherent in the sanitary section of the construction battalion as originallyconceived. Construction battalion personnel comprised for the most part highlyskilled labor with technical ratings and with only few unskilled workers.It was wasteful and damaging to morale to use skilled labor for unskilledmanual work. Wherever possible, the use of skilled construction battalionlabor was limited to the use of heavy equipment and to other skilled jobswhile unskilled manual work was done by native labor.
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The use of Army engineersfor malaria control was authorized 16 as follows:
"The Corps of Engineersis charged with the responsibility for the execution of mosquito controlwork on real property. This includes such measures as drainage, filling,larvicidal programs, and screening."
The number of troopsin the Army Corps of Engineers in the South Pacific Area was small, as comparedwith the number in the naval construction battalions. The use of such troopsfor malaria control projects was subject to the same delays encountered withnaval construction battalion sanitary sections with the added handicap thatno set percentage of troops in the Army Corps of Engineers was directed todo malaria control work. A few of these troops did excellent work on insectcontrol projects, but the total was small.
The practice was begun during 1944 of submitting consolidated estimates for all base malaria control projects to the commanding general, with the request that these projectsbe assigned to heavy equipment units. This resulted in the division of theseprojects between Army engineer units and naval construction battalions. Suchprojects were well prosecuted.
A large share ofsemipermanent work was done with borrowed equipment which was maintained andoperated by personnel of malaria control detachments and medical sanitary companies. Such equipment which was in great demand was obtained by a process of barter and exchange, the details of which were best known to Army supply sergeants and Navy warrant officers.
Thus, malaria controlpersonnel on Guadalcanal operated an average of 10 bulldozers, 2 draglines,and several disk harrows throughout 1944, and similar personnel on EspírituSanto and Bougainville operated about one-half of this amount. of equipment.A few experienced operators of such equipment were found in the various malariacontrol detachments and others were trained. The great majority of all semipermanentdrainage work done in the early months of occupation on several island baseswas accomplished in this extralegal manner. These experiences led to a recommendationto the War Department, which was approved by Headquarters, Services of Supply,South Pacific Area, to add a limited amount of heavy earth-moving equipmentto the table of organization and equipment of medical sanitary companies.This recommendation was rejected on the ground that medical sanitary companiesdid not have time necessary maintenance crews and facilities to service suchheavy machinery. This objection was theoretically valid; in practice, however,such equipment in the hands of malaria control units had an excellent recordfor days worked per machine per month and for rapid repairs when needed. 17
16 War Department circular No. 223, 21 Sept. 1943.
17 It is stillour opinion that some plan of assigning such equipment to a malaria controlorganization is essential if semipermanent control work is to be accomplishedduring the early months on a new base--Authors' Note.
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ANTIMALARIA ACTIVITIES
Training, Information, and Propaganda
The training and education program was planned to reach every officer and man in the area ona level consistent with his responsibility. This program fell into two parts:(1) The work of the area headquarters staff which developed the necessarydirectives, provided manuals, posters and other educational aids and conducteda small area training center; and (2) the work of base and division malariacontrol groups which directed the mass education program.
The area stall preparedsix pocket-sized manuals, three on malaria and one each on dengue, filariasis,and rodent control. The three manuals on malaria were written respectivelyfor medical officers, for line officers, and for enlisted personnel. About500,000 copies were printed locally to provide one for every officer andman in the area. The area staff included an artist, who, over a 2-year period,produced 15 posters, a monthly pinup calendar, and a weekly cartoon for theSunday edition of the local mimeographed paper. "Malaria Moe" and the FrankMack versions of a pinup girl and of an anopheline mosquito were found innearly every tent and quonset hut in the area. Posters were reproduced innumbers to supply one large and one small size for every 200 men. One calendarwas printed monthly for every five men.
A library of malaria control films was obtained and circulated to all base and division groups which arranged for command showing of the more important ones. Only two filmswere considered adequate, a "Snafu" film on malaria and a film produced bythe Army Air Corps, TF1-3343. Such excellent results were obtained from thefew satisfactory films that were available that it is to be hoped that moreand better training films will be prepared for these subjects.
A monthly newsletter was found to be a most successful method of disseminating current information to malaria control officers, hospitals, and base and division surgeons.
An area training center in malariology and other insect-borne diseases was established first on Efate and later on Espíritu Santo. It began late in 1942 with smallclasses of three to five officers for 2-week periods. The students at thisschool included all newly arrived malariologists and such troop unit malariacontrol officers as could be spared from their organizations. The schoolwas located on the grounds of a large hospital which had a high census ofpatients ill with malaria and other tropical diseases and who were availablefor clinical and parasitologic study. The medical staff of the hospital aidedthe area malaria control staff in the teaching program. Adequate parasitologicand entomologic collections were built up and a small but good library wasobtained. Thirty malariologists, or more than two-thirds of those
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who worked in the area, attended theseschools as did a larger number of troop unit malaria control officers.
The training program on each island or base was divided into three parts: An apprenticeship systemfor newly arriving personnel of malaria control and survey detachments; ashort school for troop unit antimalaria details; and a simple educational program for every man in the area.
The apprenticeship system was devised to meet the needs of incoming malariologists, entomologists, parasitologists, engineers, and the men of their detachments, a few of whomwere experienced in the problems peculiar to the South Pacific Area. Thisapprenticeship period lasted from 1 to 3 months. The teaching staff consistedof the entire personnel of a veteran group, and the curriculum was the dailywork of this established group. After a short time, the newly arrived personnelwere assigned a small area and were made responsible for all phases of antimalariawork therein, before being given a completely independent assignment.
It was often possible to place six or eight men of a control unit with a naval construction battalion or Army engineer company, where they rotated through a program of work withdragline crew, transit crew, dynamite gangs, and heavy maintenance section.
The training of enlistedpersonnel as technicians qualified to read blood smears for malaria was oneof the urgent problems in the early period. The first school for technicianswas started at Efate, using as instructors corpsmen who had been trainedat the Naval Medical School. From 50 to 100 routine thick-blood smears wereexamined each day by these corpsmen and were available for teaching purposes(fig. 54). Similar schools were established on Espíritu Santo, Guadalcanal,and other bases as soon as malaria control groups arrived. Students weretrained either singly or in small groups. Over 450 technicians were trainedin the first 2 years of this work with an improvement in malaria diagnosisthroughout the area to the point where over 95 percent of all cases wereconfirmed by the laboratory.
The School for TroopUnit Anti-Malaria Details was designed to teach the elements of larviciding and other control measures to the men who comprised these details in each company. This activity was initiated by ComSoPac Serial 01619, issued on 13September 1943 and revised on 19 October 1944 by ComSoPac Serial 02158.
An effort was madenot only to show how to control malaria but also to explain the rationale of this work, thus creating a nucleus of informed officers and men in each battalion and company. An average class consisted of 10 to 15 students. Theofficers and selected enlisted men from base and division malaria control groups comprised the faculty. The period of instruction was usually 2 to 3days. The presentation of subject matter was elementary. The unit medical officer was required to attend because he was expected to use this type ofpresentation in his talks with the men of his
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FIGURE 54.- Recording results of microscopic examinations of blood smears.
organization. Emphasis was placed onpractical fieldwork. Between 4,000 and 5,000 officers and men attended theseschools during the first 2 years of their activity.
Educational Program for All Personnel
All of these programs were concerned with personnel engaged in full- or part-time insect and rodentcontrol work. The basic educational program, to be described, aimed to impressevery man with the importance of malaria and with how he might protect himselffrom mosquitoborne disease. Few troops had had any education in malaria beforearrival in the area. The need for this educational work was so apparent thatprograms were initiated almost simultaneously on several staging bases includingthe Fiji Islands, New Zealand, and New Caledonia. The value of these earlyuncoordinated efforts was immediately evident. At the same time, there wasapparent need for a uniform area training and education program, for approvedtraining manuals, and for a publicity program employing the radio and othereducational aids. A theater directive was first issued in mid-1943 and wasrevised by ComSoPac Serial 02158, 19 October 1944. An extract follows:
Training Program in Malaria Control
1. Unit Commanders will allot in the training schedules sufficient time for the proper instruction of their troops in the principles of malaria prevention.
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2. Lectures will be given to small groups of men by their respective medical officers. These lectures will cover the following:
a. Military importance of Malaria.
b. Nature of Malaria, How Transmitted and Effects.
c. Individual Protective Measures, Conditions in Which Each is Applicable, Especially in Combat.
Repellents,
Use of Ordinary Clothes for Protection.
Spray-killing of Adult Mosquitoes.
Bed Nets.
Atabrine Suppressive Therapy.
Avoidance of Unnecessary Exposure.
d. Control of Mosquito Breeding.
e. Man-made Malaria--How to Avoid It.
3. All personnel will be given initial instruction in prevention of malaria by lectures andmotion pictures as soon as practicable. Subsequently, a review of the subjectwill be carried out at least once a month.
4. Additional instructionwill he given to officers and non-commissioned officers, or petty officers,covering especially the selection of campsites, the hazard of natives asa source of malaria, and the enforcement of precautions under varying fieldconditions. Emphasis will he put on the responsibility of officers and non-commissionedofficers for good "Malaria Discipline" and its importance to military success.Arrangements may he made to have members of Base Malaria Control Units assistin this program.
5. To aid in this program permanently based Malaria Control Units (or Island Surgeons) will issue the following malaria training manuals:
All Medical Officers: MTM No.1. Prevention of Malaria in Military and Naval Forces, SPA.
All Officers: MTM No.2. Military Malaria Control, in the Field.
Enlisted Men: MTM No.3. Malaria. Mosquitoes, and Men.
Movies, additional literature, posters, and other material will also be made available by Malaria Control Units.
6. Every unit willperiodically conduct field exercises in the practical application of antimalarialmeasures. On maneuvers, these measures will be standard procedures.
Arrangements were made for brief radio announcements on each base every evening which reminded listeners to roll down sleeves, to use repellent, and to take other precautions. The radio stations were known as the Mosquito Network, and on Guadalcanal a program of recorded music known as the Atabrine Cocktail Hour began each evening with a plug for malaria or dengue control.
Parasitological SurveyActivities
The parasitology sections of the malaria survey units participated in the educational and inspectionactivities of the malaria control groups. In addition, they were chargedwith the responsibility of seeing that all blood smears were read correctly.Upon request, they trained technicians for the hospitals, sickbays, amidother installations where blood smears were examined. They also made periodicchecks on the accuracy of the diagnoses made by these installations. Theyprovided a microscopic diagnostic service for dispensaries, sickbays andother installations which were unable to examine slides them-
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selves. In 1943 alone, over 75,000 slideswere read on Guadalcanal. The parasitology sections carried out surveys ofmalaria and filariasis among natives and others. The parasitologists alsocollected and compiled statistical data on malaria incidence in the troops.
Entomologic Survey Activities
The personnel andorganizational structure utilized for entomologic survey activities in theSouth Pacific Area were discussed previously (chart 25). In actual practice,this organization was an exceedingly flexible one, adaptable to peculiarcircumstances and problems as the need arose, and Army malaria survey detachmentswere seldom used as distinct and independent units. Responsibility for surveywork was assigned on an area basis, with an entomologist, either Army orNavy, in charge, and personnel from either or both of the services detailedas needed or available. An area entomologist was on the staff of the areamalariologist to provide overall coordination of the work. Island entomologistswere designated to coordinate the survey work on the larger bases; namely,Bougainville, Espíritu Santo, and Guadalcanal.
In general, within a designated area, the entomologist and his crew were responsible for surveys to determine the incidence, distribution, and biology of arthropods of medicalimportance; for recommendations as to the areas requiring control operations,their proper treatment, and relative importance; for routine inspection surveysto evaluate the effectiveness of control operations; and for maintenanceof appropriate records of insect populations and their fluctuations in responseto control activities or other factors. Special investigational projectswere undertaken as times permitted or the need arose.
The duties of thearea entomologist were to advise the area malariologist concerning the broadaspects of the entomologic work, to aid in the procurement of entomologicsupplies, and to assist base entomologists in the establishment of surveyprocedures. A similar relationship existed between the island entomologistsand the malariologists of the respective bases. In no instance were thesecommand positions, and the personnel assigned to them acted merely as technicaladvisers and coordinators. The value of this type of coordination was recognized,particularly since it facilitated the dissemination of ideas and informationof value to the general program. The area entomologist prepared and distributeda monthly newsletter which included pertinent entomologic and engineeringdata. Monthly meetings of the entomologists on Guadalcanal were held, andthese were occasionally attended by entomologists from Tulagi. These meetingswere conducted in the best entomologic traditions and greatly facilitatedthe problem of coordinating survey work on the base.
Field survey work within an assigned area was usually conducted by from 7 to 10 enlisted techniciansin addition to the officer in charge. The senior noncommissioned officerwas in direct charge of both field and laboratory work,
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2 or 3 men were usually detailed toinsectary and laboratory activities, and the remainder to field surveys. Areaassignments varied in size, depending upon the complexity of the problems encountered and the terrain involved. They usually consisted of from 10 to45 square miles of territory. The entomologist and the senior noncommissioned officer were necessarily familiar with the entire territory in a general way,and field scouts were expected to become acquainted with their assigned subareasin a detailed fashion.
In actual practice, no sharp distinction could be made between initial exploratory surveys androutine inspection surveys, since the one gradually evolved into the other.Under ideal conditions, initial surveys of a territory followed criticalinspection of maps and aerial photographs of the area. Unfortunately, duringthe early phases of the South Pacific campaign, this was seldom possible.The lack of adequate maps for malaria control activities reflected the situationfrom the tactical standpoint. There were no good maps of Guadalcanal beforethe invasion, nor was that deficiency corrected throughout the combat period.Initial surveys were often sketchy and incomplete, either because of combatconditions, inadequate personnel, or other factors. The objective of theinitial surveys was to determine as quickly as possible the location, extent,and description of actual or potential mosquito-breeding places; the recordsof current adult and larval populations; and the locations of native villagesor other possible reservoirs of tropical diseases. As survey work progressed,the accumulated information was used to draw up detailed recommendationsfor a control program. As the control program developed, the survey activitiesbecame progressively more routine, but field survey personnel were at alltimes enjoined to report on the necessity for new projects to correct potentiallydangerous situations, as well as the need for maintenance work of any kind.Because of the ever-changing situations on most bases, initial survey activitieswere never really terminated.
Routine survey activitieswere primarily aimed at improving the larvicidal program. Various attemptswere made to evaluate the control program through sampling the adult mosquitopopulation, but these were not generally successful. As indicated previouslyin the discussion of the habits of A. farauti, all attempts to estimatethe population of this species through counts of adults in daytime restingplaces failed, or were of very limited practical value. The routine operationof mosquito light traps seldom produced Anopheles in sufficient numbersto be of significance and in areas of relatively low populations seldom producedany specimens. Night catches of mosquitoes were fairly reliable as a measureof the population but were time consuming if properly carried out. For thesereasons, sampling of the larval population was usually the method of evaluatingthe control program. In addition to supplying a more sensitive measure ofpopulation fluctuation, larval sampling permitted immediate application ofcontrol measures.
It was recognized early in the work in the South Pacific that close coordination of survey andcontrol activities was necessary to attain the highest degree
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of efficiency in the approach to malariaand epidemic disease control. This was particularly true with respect tothe larvicidal program. In order to facilitate coverage of all available watersurfaces, survey crews routinely maintained maps showing the location ofwater catchments and the results of larval population sampling. Since primaryemphasis was placed on malaria control, the location of A. farauti breeding foci was indicated on the map in red, the density of the populationbeing shown in terms of a fraction, the number of larvae over the numberof dips taken. Thus 150/60 meant that a total of 150 larvae was taken in60 dips. Populations of culicine larvae were similarly recorded in blue.These data were recorded daily on large-scale wall maps covered with a transparent overlay.
At the end of eachchecking period, usually 1 week, the data were transferred to record-size maps, and the overlay was cleaned off before the results of the next survey were added. Control crews consulted the map daily and guided their efforts accordingly. This system permitted personnel concerned to note at a glance the situation throughout the area and enabled the entomologist and engineer to follow, week by week, the progress being made in the elimination of "hotspots." These data gave an accurate picture of the potential malariousness of an area long before that information could be derived from reports of incidenceof the disease.
Antimosquito Operations
The story of mosquito control operations in the South Pacific is a story of improvisation and salesmanship.Under the stress of wartime conditions, it was necessary to work under thehandicap of critical shortages of personnel and equipment. Much of the equipmentavailable during the early phases of the work was ill adapted to the joband had to be discarded or constantly repaired. Attempts to obtain heavyearthmoving equipment always met with competition from high priority projectssuch as airfield and road construction. Control work other than hand larvicidingwas delayed for many months after occupation on all of the bases occupiedduring the first 1 1/2 years of the campaign. Larviciding wasnot started on Efate and Guadalcanal until a malaria epidemic was well underway.
DDT, with its immenselaborsaving potentialities, did not become available for general use untilafter the middle of 1944, by which time the major task of malaria control--thaton Guadalcanal--had already been accomplished. The urgency of the situationin late 1942 and early 1943 made it necessary to undertake the work withall possible speed. A studied and strictly scientific approach was not possible.Although primary emphasis was placed on malaria control from the outset,it was not known how many vectors of this disease were present, or what othermosquitoborne diseases might be encountered. It was felt that quick controlof mosquitoes in general would ultimately be the cheapest control of malariaand other epidemic diseases transmitted by mosquitoes.
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Antilarval activities
Larviciding .- The initial approach to mosquito control was largely through elimination of the immature stages of development. In part, at. least. this decision wasdictated by the limited materials at hand, mostly diesel oil and a smallnumber of hand-operated sprayers. Only limited drainage could be accomplishedwith the few troops assigned to malaria control activities, and line andservice organizations were slow to cooperate in reducing the extensive watersurfaces unless compelled to do so for personal comfort. Many months wereto pass before an adequate number of vehicles and power sprayers was available,and airplanes were not used until after DDT became available late in 1944.
Of the several makesof hand-operated sprayers that were ultimately used, the 3-gallon chemicalwarfare sprayer, M1, was generally the most satisfactory. When modified witha suitable nozzle and oil-resistant hose and gasket, it made a fairly lightand serviceable item. It had the added advantage of having interchangeableparts, a feature that did not apply to some other types of sprayers furnishedas equipment to Army malaria control units. Until power sprayers became available,most larviciding was done with this item, carried by men on foot. In orderto improve the efficiency of the operation, it was the general practice todistribute drums of oil to the field by truck, spotting them at strategicplaces so that walking could be cut to a minimum.
Once power sprayers became available, they were mounted on jeeps or weapons carriers and used to patrol the miles of water-filled roadside ditches and ruts that existed on nearly every base. Complete coverage of all static water surfaces was attemptedeach week on most bases, although this frequently could not be accomplisheduntil the program was well underway. Eventually, it became the general practicefor organizations to larvicide within their own cantonment areas, while thebase malaria control organization assumed responsibility for all other larvicidalwork. Larviciding crews were usually assigned definite areas of responsibilityand were expected to become familiar with all details of the area that requiredattention. Crews usually contained 5 to 15 men each, depending upon the extentof the area to be covered. A noncommissioned officer was in charge of eachcrew. The members of the crew might work singly, in pairs, or as a group,again depending upon the problem at hand. Under conditions of normal rainfall,the crew was expected to be able to cover its assigned territory once in4 or 5 days. This schedule left a safety factor of 2 or 3 days for repairof equipment, rainy days, and recreation.
Larviciding was notcustomarily carried out during periods of excessive rainfall because of thequick runoff of water and larvicide. On some bases, it was found expedientto organize "shock" oiling crews, usually of two or three men, whose dutyit was to cover breeding areas missed by the regular crews. When unoiledbreeding areas containing either fourth stage larvae or pupae of Anopheleswere reported, it was customary for the shock crew to cover the
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area on the same day, regardless ofthe time of day at which the report was received. To expedite this work, surveycrews resorted to the use of "flag" in the field to mark the breeding site,or, if necessary, a survey man would accompany the oiling crew into the fieldto point out the site. Although this system occasionally caused some hardshipthrough disruption of planned after-hour activities, it served to emphasizethe importance of thorough coverage. The comments of the shock crew calledupon to take care of such special assignments were usually sufficient toimprove the work of the regular crew.
The routine use ofDDT, when it became available, resulted in a great economy of both labor anddiesel oil. Usually, the spray schedule was not altered. Some larvicidal crewswere equipped with 2-quart continuous-spray dispensers, and it was foundthat where scattered small pools were involved this item of equipment wouldhold enough solution to last a man for one-half day of work. Crews that continuedto use knapsack-type sprayers adjusted the nozzles to the finest spray andcould work all day without refilling. Spray crews were taught to apply onlya minimal amount of the solution and to take advantage of wind drift in applyingthe larvicide to extensive water surfaces.
Dusting for the controlof mosquito larvae was little practiced in the South Pacific Area. Beforethe use of DDT, some attempts were made to use paris green for the controlof Anopheles, with varying success. This arsenical was used as a temporarycontrol measure along grassy stream margins and around the edges of swampsuntil cleaning could be accomplished. Condemned flour was the most commonlyused diluent but was unsatisfactory because in the humid climate bacteriaand mold contamination tended to make it lumpy. Lime, pyrophyelite, and talcwere not available for use as diluents. DDT dust, 10 percent, gave excellentcontrol but was little used because of lack of suitable dusting equipment.Survey men often carried a 2-ounce can of DDT dust for treatment of rainbarrels and small road-rut areas.
Airplanes were firstused in the South Pacific for the dispersal of insecticides in May 1944.This type of work was initiated on an experimental basis by members of NAMRU(Naval Medical Research Unit) No. 2 with the cooperation of base malariacontrol personnel. The Husman-Longcoy spray apparatus was installed on aPiper Cub plane. It was first used for evaluating the effectiveness of aerialspraying in heavy jungle areas of the tropics, the equipment having alreadybeen thoroughly tested for performance at the laboratory of the U.S. Departmentof Agriculture, Orlando, Fla. The success of the first tests, and the increasingavailability of DDT, made it apparent that this method of application ofinsecticides would greatly increase the efficiency of the entire programand would, in addition, obviate the necessity of many extensive drainageprojects then under consideration.18 It offered, for the firsttime, a practical method of controlling mosquitoes in areas that
18 Report, Capt. Bruce E. Sasse, SnC, to Officer in charge, Malaria and Epidemic Control, South Pacific Area, 19 June 1944, subject: Airplane spraying.
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could not be entered because of the presence of uncharted landmines or other explosives. Steps were immediately taken to utilize aerial dispersal of DDT solutions and to explore the practicability of other types of airplanes for this work.
Several types ofequipment for use on airplanes were developed in the South Pacific Area, 19 some of which were thought to be superior to the Husman-Longcoy spray apparatus because they could be readily constructed from material availableat most airbases. Exhaustive tests, involving swath width, optimum flightspeeds, droplet size, and biologic evaluations were conducted with variousairplanes and items of spray equipment. No large multiengine airplanes wereused routinely in the South Pacific since the terrain and the problems existingat that time were thought not to justify use of large aircraft. Aircraftused on both a routine and experimental basis included 65- and 85-hp. PiperCubs and TBF and TBM planes. Tests were also conducted with F-AU airplanes,but the limited carrying capacity and high speed of this plane made it impracticalfor use in rear areas.
In order to increase the efficiency of aerial spray operations, and to take full advantage of theshort period during the day when atmospheric conditions were suitable forspraying, a special ground crew was developed to load and service aircraft. This unit consisted of two or three men with a. 3/4-ton truck andtank trailer. Accessory equipment included such items as a motor-driven fuelpump, a hand-operated fuel pump, water-stop filter, fire extinguishers, sundrytools and replacement parts, DDT solution, and gasoline for the airplane.Thus equipped, the unit could move to the airfield nearest the site of operationsfor the day and service two Cub-type planes for one-half day of operations.
The effectiveness of aerial dispersal of larvicides in the control of mosquitoes exceeded thefondest hopes of the personnel in the South Pacific Area. Even in areas coveredby a dense jungle, the fine spray penetrated to small ground pools, and theresults were conclusive. In retrospect, it appears that the use of DDT andairplanes could have prevented the disastrous epidemics of malaria that delayedand threatened the success of the early phases of the South Pacific campaign.
During the latter part of 1944, the increasing use of DDT solution in diesel oil for both aerialand ground dispersal brought out a new operational problem. Hand mixing ofthis material was slow and tedious, and when the consumption on larger basesrose to several hundred gallons daily it was necessary to devise some meansof mechanical mixing. The most practical of the methods devised for turningout large quantities of solution involved conversion of a 400-gallon capacityorchard sprayer to a mixing vat. A satisfactory
19 (1) Report, Lt. S. R. Fallander, USNR, February 1945, subject: Analysis of Aircraft Sprayingand Equipment for Routine Use in Malaria Control. (2) Report, Lt. Comdr.H. S. Hurlbut, USNR, Guadalcanal, dated 10 and 12 Feb. 1945, subject: Dropletsize, Distribution and Swath Width for Husman-Longcoy and Fallender TypeAirplane Spray Equipment.
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solution could be obtained in a short time by means of mechanical agitation, and this means was used to supply DDTmixtures to all base control units and sanitary companies on Guadalcanal. The solution was returned to the empty diesel oil drums, which were used totransport the material from the central mixing station to substations. Bycontinued re-use of the same drums, any residues of precipitated or undissolvedDDT were not wasted but were retained in subsequent lots of the solution.An improved method for the preparation of DDT-diesel oil solution on a largescale was subsequently developed and is described in the section on Okinawa.
Filling. -If DDT had been available from the beginning of malaria control activities in the South Pacific, it is possible that much less work aimed at reducing the existing water surfaces would have been required. However, although dieseloil was an effective insecticide when properly distributed, its spreadingqualities on water were not sufficient to give good control in pools andswamps containing abundant vegetation or debris. Under such circumstances, it became imperative to bring the total water surfaces requiring larvicidal treatment within the capacity of the crews available. Accordingly, a systematic attempt was made to eliminate all possible surface water. Among the first of the projects of this type was the filling of shell and bomb craters, abandonedbomb shelters, pits along roads, and foxholes. When bulldozers were available,they were used for the larger water catchments. Smaller catchments, suchas foxholes, usually in somewhat inaccessible places, were best sought outand filled by crews of Melanesians. Since Melanesians customarily wore nofootwear, one important modification had to be made in equipment to assureits proper use. Shovels were provided with a broad plate on the blade nextto the handle so that foot pressure could be applied.
One of the most importantof all filling operations was the elimination of road ruts by the use ofa disk harrow. Especially on Guadalcanal, where innumerable miles of rutswere cut through the extensive grasslands, this was a most important contributionto malaria control. Once disked and closed to vehicular traffic, these areas were quickly revegetated and gave no further trouble.
Clearing and streamcleaning. - The clearing of undergrowth during the process of establishingbivouac areas automatically reduced the existing mosquito population to aconsiderable extent through the elimination of harborage. Although this wasan important contribution to mosquito control, it was not considered sufficientlyimportant to warrant clearing outside the cantonment area. The major portionof the clearing that was done for mosquito control consisted of cutting awaythe marginal growth along streams to expedite the passage of oiling crewsand of removing emergent aquatic vegetation and debris from swamps and slowstreams. Cleaning of streams hastened the runoff of water and greatly improvedthe drainage of an area. Since slow, sluggish streams and swamps were importantsources of anopheline breeding during periods of little rainfall, reductionof the mosquito population in
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such places delayed the spread of breedingto temporary surface pools that developed following heavy rains.
The job of stream cleaning and clearing of underbrush was accomplished by native laborers wheneverthey were available. Troops were very reluctant to do this type of work becauseit was dirty, tiresome, and frequently resulted in fungus infection of theskin. Moreover, Melanesians were infinitely more skilled in the use of machetes,the preferred tool for this type of work, and could accomplish a great dealmore than a similar number of troops working under the same conditions; moreover,the cost was relatively low.
Stream cleaning inthe Solomon Islands was not entirely a dull routine. Many of the sluggish streams were inhabited by crocodiles, some of which reached a length of 10or 12 feet. When one of these ill-tempered reptiles was encountered by anative crew, a scene of wild confusion ensued, which might be compared withthe spectacle of a pack of dogs around a raccoon at bay. The Melanesians wereanxious to kill or capture the quarry but were still respectful of the damagethat could be inflicted by it. The chase nearly always ended in a feast ofcrocodile meat. The tail was much prized as food, the meat being white andshrimplike in taste when properly prepared.
Drainage. - Drainage projects planned and carried out by the malaria control organization in the South Pacific were customarily accomplished either by hand ditching, dragline ditching, or the use of explosives. By July 1944, on all bases combined,there were 157 miles of dragline ditches, 153 miles of hand-dug ditches,and 26 miles of ditches made with explosives. These figures involve onlyoperations done primarily for the purpose of mosquito control. They do notinclude ditching accomplished by organizations engaged in establishing orimproving bivouac areas, ditching in connection with new road construction, or shallow ditches cut with a pull grader.
Draglines, either 3/8 or 3/4-yard capacity, were used primarily on majordrainage projects such as draining swamps, channeling sluggish streams, deepening existing roadside ditches, or connecting oxbows with stream channels. In swampyareas, the use of mats was necessary, especially during the rainy season.Ditching machines were of little value and were little used. When such equipmentwas used, it was necessary to follow up with a hand crew to cut the ditchsides back to a 45-degree angle to prevent cave-ins and ditch blockage. Undergroundtitle or tile inverts were not used.
Many of the roads constructed during the early phases of the campaign were completely unsatisfactory from a drainage standpoint. This was also true of some airfields, although Koli Field and Koli bomber strip, constructed in the flat alluvial plain onGuadalcanal, were notable exceptions. The most common fault in road constructionwas failure to cut ditches to grade and failure to install sufficient orproperly placed culverts and connecting drainage with stream courses. Forexample, the main highway on Guadalcanal, between the little Tenaru and NalimbiuRivers, was so constructed that during the rainy season of 1943-44 it blockedthe drainage of approximately 500
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acres of grassland to the south which was flooded with water to a depth of several inches. In order to eliminate this hazard, it was necessary to cut several miles of shallow ditches with a pull grader and to connect the entire network of ditches into a main ditchleading to the Nalimbiu River.
Hand ditching wascustomarily limited to the construction of shallow ditches. Most medical sanitarycompanies had ditching platoons organized to carry out such projects. Melanesianswere not skilled at ditch digging and were little used for this purpose.Feeder ditches from bivouac areas were ordinarily dug by details from theorganization concerned.
In very swampy areas,explosives proved the most practical method of ditching. Some work was accomplishedwith dynamite, but this item was difficult to obtain and, being inferiorto bangalore torpedoes for use in swamps, was not widely used. Bangaloretorpedoes, metal pipes packed with high explosive, condemned for combat useand hence readily available to malaria control organizations on some bases,proved ideal for use in soft, mucky soil. By laying these bangalores in aseries and pressing them slightly into muck or soft mud, several yards ofditch could be dug with one explosion. Bangalores had the added advantagein that upon fragmentation the hundreds of pieces of sharp steel cut awaythe undergrowth and small roots, leaving a well-trimmed ditch. If greaterdepth was desired, a second series of bangalores, laid in the first ditch,would complete the job. In the same way, small shallow streams could be rapidlycleared of muck and debris.
On those islands having a thin topsoil and coral substratum, vertical drainage could be accomplishedwith relatively little effort. On Green Island, for example, vertical drainageof small catchments required only a few holes punched through the soil intothe porous coral beneath. A single blow with an iron rod would often sinkthe rod to a depth of several feet. Limestone sinkholes were present on someof the islands, and although they often silted in and became closed theycould usually be opened with a single charge of dynamite. On Munda, Ondongo,and Bougainville, large bomb craters in some instances gave excellent verticaldrainage.
Flushing. - Flushing dams were constructed in suitable streams in a few instances, and where accompanied by stream cleaning they were very effective in controlling mosquito breeding of all kinds. Without stream cleaning, they were ineffective. In all, a total of nine damns were constructed, seven on Guadalcanal and twoon Efate. In view of the difficulty of construction, and lack of suitable materials, it is doubtful if wide use of flushing dams under most conditions of military occupation is justified.
Natural control . - Gambusia, the surface feeding fish often used in tropical areas for the control of anopheline mosquitoes, was used on several bases in theSouth Pacific. Stocks were placed in swamps and permanent ponds on EspírituSanto and Munda, and in wells and cisterns of Efate. They had been stockedon the Russell Islands many years previously. Their chief value was in reducingbreeding in marginal areas not readily accessible for larviciding.
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They were of little or no value in the presence of vegetation. Except for use in wells and cisterns,they were not routinely stocked within the established control areas. Evenafter establishment, constant maintenance and restocking was necessary.
Flumes. -Coastal lagoons on Bougainville, Green, Emirau, and Guadalcanal Islands constitutedone of the most difficult control problems encountered. There were more than60 lagoons along the coast within the occupied area on Guadalcanal. Theseserved as permanent breeding foci for A. farauti during the dry season,and even though breeding in other areas was minimal at that time the populationsdeveloping in the lagoons served to repopulate adjacent areas whenever surfacewater became available. Control of breeding in lagoons was therefore givenhigh priority in the control program.
These coastal lagoonsordinarily remained closed for long periods of time, although they were occasionallyopened by flash floods during periods of heavy rainfall. Water within thelagoons rose to a level of 3 or 4 feet above sea level and provided idealbreeding sites for malaria mosquitoes. Cutting ditches through the enclosingsandbar offered only a temporary solution since wave action would quicklyclose the mouth of the stream, usually within 24 hours. The problem was finallysolved by the use of flumes made from a series of oil drums with the endsremoved and welded together end to end. The lagoon end of the flume was setapproximately 6 inches below sea level at mean low tide, and the flume extendedout through the sandbar until the opposite end was approximately 12 inchesabove the floor of the sea beyond the area of normal surf action. The lengthof the flume depended upon the pitch of the beach. The first flumes installedwere placed at the narrowest point in the sandbar, but experience showedthat there was more likelihood of the structure being washed out during stormsif placed at this point. Subsequently, it was the general practice to placeflumes well to one side of the narrow point in the sandbar.
Flumes were held in place by pilings placed on each side at intervals of 5 feet. These pilings were set with the aid of a water jet from a 500-gallon-per-minute fire pump.An experienced crew of 14 men with dragline, bulldozer, and fire pump couldset double flumes some 200 feet long in from 4 to 6 days. Flumes were preparedin sections of from 15 to 20 feet in length at a welding shop and transportedto the job in sections. Multiple flumes were required in some instances forlarge lagoons, six being the maximum installed at any one lagoon. When multipleflumes were set, they were usually laid in pairs, each pair being somewhatremoved from the adjacent pair.
Flumes properly installednot only permitted the water in the lagoon to be drained, but permitted entryof some sea water and at least a slight change in the salt content of thewater in the lower end of the lagoon. There was also daily fluctuation ofwater level in the lagoon. Under these conditions, the flora of these coastalswamps either disappeared, or was considerably altered. Once flumes wereinstalled, there was usually little necessity for other control measures.
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Agriculture . - Cultivation of extensive areas of former grassland on Guadalcanal proved to be an effective mosquito control measure. Eventually, some 2,500 acres between the little Tenaru and Nalimbiu Rivers were under cultivation for thepurpose of supplying troops with fresh vegetables. Much of this grassland area had at one time been badly rutted by vehicular traffic, and although this situation was largely corrected by the time the farm was established the cultivation of the area assured freedom from mosquito breeding. Even duringperiods of heavy rainfall, the surface water in the cultivated areas didnot persist long enough to permit breeding.
Antiadult activities
Space spraying . - During the early phases of the South Pacific campaign, the only space sprays available were the petroleum base sprays dispensed with old-fashioned "flit guns." These were more often used against flies than mosquitoes. Theywere relatively effective in screened messhalls and similar places but weretotally ineffective in open quarters. Pyrethrum Aerosol dispensers, the well-known"mosquito bombs," became available in limited supply in forward areas, duringthe first half of 1943, and were first used during a combat operation inJuly 1943 in the New Georgia campaign. By the time of the landing on Bougainvillein November 1943, an adequate supply of Aerosol bombs was available and theywere widely used. As new supplies arrived, there was a gradual replacementof pyrethrum Aerosols with bombs containing a small percentage of DDT. Five-poundrefillable dispensers were used to some extent in messhalls, recreation areas,theaters, and similar places where large amounts of spray were needed.
Aerosols were littleused in combat areas but were extremely valuable in rear areas. Proper useof an Aerosol bomb in shelters occupied during night air raids would giveprotection to a number of men, and their use in this manner was encouraged.In unscreened quarters and open foxholes, the effect was extremely transitory,especially during periods of even slight air movement. For killing mosquitoesin screened quarters or in mosquito bed nets, Aerosol bombs were unexcelled.Aerosol preparations were also widely used to spray huts occupied by nativelaborers, in order to kill any malaria infected mosquitoes that lingeredfollowing a nocturnal blood meal. A daily schedule was established for thiswork, with a native dresser trained to do the spraying.
Thermal Aerosols were used on a few bases in the South Pacific, largely on an experimental basis.20 Although they were of value under certain circumstances in reducing existing adult mosquito populations, their general use was notpossible because of limited road nets. Nighttime operation was most effective,since the atmospheric conditions prevailing at that time usually held theAerosol fog close to the ground. Daytime applications along the beach
20 Brescia, F.. and Wilson, I. B. Treatment of Native Villages with the Aerosol Generator. J. Econ. Ent. 40: 313-316, 1947.
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area, for reduction of sand fly populations, were successful in some instances but the effect could seldom be noted formore than 2 or 3 days.
Residual spray applicationsof 5-percent DDT in kerosene were by far the most effective insecticide applicationsfor reduction of adult mosquito populations in the South Pacific. Eventually,nearly all buildings and enclosed tents were so treated. Most of the workwas done with a power-driven paint sprayer operating at low pressure; thesolution was applied to screens with a paintbrush. Other types of spray equipmentwere also used for treatment of the interior of structures. Regardless ofthe equipment used, the recommended rate of application was 1 quart per 250square feet of surface. The general "rule of thumb" was to spray wooden surfacesuntil wet, but just short of runoff. This treatment was not only effectiveagainst mosquitoes and flies but was remarkably effective in eliminatingants from quarters where they had been extremely annoying before the useof DDT.
DDT residual-type spray was also used to impregnate bed nets. This practice was begun during the latter part of 1944, and the methods developed at that time were later used for treating bed nets and jungle hammocks for the use of two divisions. The solution was applied with either a power-driven paint sprayer or the standardchemical warfare decontamination sprayer such as was widely used for larviciding.Application was at the rate of 1 gallon per 6 to 8 nets. The method of applicationwas to arrange the nets in a pile, spray the top net, turn it to start anew pile, and then spray the opposite side. Operating in this fashion, 6men with 4 hand-operated sprayers were able to spray from 60 to 100 netsper hour a similar crew working with power-operated sprayers could treattwice as many in the same period of time. This included preparation of thenets, spraying, and hanging the nets to dry.
Nets tested immediately after treatment and after being stored for 1 month were lethal to A. farautiand other species of insects used for biologic tests of the material.No further information as to the duration of effectiveness was obtained.
Screening . - Screening of any kind was practically nonexistent during the early phasesof the campaign, but by early 1944, it was available in adequate amountsin all except forward and combat areas. Table 67 shows the relationship betweenlength of occupation of each base and the percentage of screened quartersas of June 1944. Cloth bobbinet was preferred to wire for field use and foruse on installations near the shore where it was exposed to windblown saltspray. During the time that the amount of screening was limited, the followingpriorities were established: Hospitals, kitchens, and messhalls; showers,particularly for organizations with men on night details; latrines; and offices,tents, and all other living quarters. Judicious use of the available screeningmaterials undoubtedly contributed greatly to the reduction of malaria, aswell as to the general comfort.
Bed nets were probablythe most valuable single mechanical barrier against mosquitoborne diseases.There were instances on Guadalcanal and elsewhere
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TABLE 67. - Estimated percent of quarters screened,1 South Pacific Area,June 1944
during the height of malaria epidemics where less than a week of bivouacking without bed nets resulted in a high infection rate among the troops concerned. A single night of exposure often resulted in considerable malaria in an organization. Because of such costly experiences, orders were issued making it the responsibility of each officer and man that bed nets should be available on the first night ashore except among troops actually in combat. Jungle hammocks were issued to many troops, including entire divisions beginning late in 1943. Where proper use of thisitem was possible, it gave excellent protection. However, the issue of junglehammocks to all personnel of a combat force was probably not justified becausethese relatively bulky pieces of equipment were among the first to be discardedduring combat operations. Further, it was seldom possible for all the menof a division to find suitable places for suspension of the hammocks. Headnets were practically never used for protection from mosquitoes, and theirroutine issue in the South Pacific Area was not considered justified.
Repellents . - Repellents were potentially one of the more valuable means of personal protection from mosquitoes and mosquitoborne diseases but were relatively little used for their intended purpose. They were more often used for protection from pest mosquitoes rather than Anopheles, and it is doubtful if repellentscontributed materially to the prevention of malaria. Dimethyl phthalate,the most effective repellent for Anopheles in the southeastern UnitedStates, was comparatively ineffective against A. farauti. It was effectiveagainst chiggers and was used for that purpose on Bougainville where scrubtyphus threatened to become a serious military disease. Rutgers 612 was superiorto dimethyl phthalate for protection from A. farauti. The standardizedrepellent, consisting of 6 parts dimethyl phthalate, 2 parts Rutgers 612,and 2 parts Indalone, was not available until 1945.
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In spite of the ineffectivenessof the repellents against A. farauti, their failure as a means ofpreventing malaria must be attributed more to antipathy toward their usethan the fault of the item itself. Combat personnel often claimed that theenemy could smell the repellent if the wind was in the right direction. Servicetroops objected to the general messiness of the solutions and to the factthat dimethyl phthalate is a solvent for plastics. On Guadalcanal, nursesquartered in a beach area where sand flies were annoying refused to use repellentsfor protection but at the same time used copious quantities of an equallymessy suntan oil. Supplies of repellent were adequate after the middle of1943, and a surplus of over 12 million bottles by the end of 1944 attestedto the failure to use this item.
Suppressive Medication
Administration policy and procedure
Atabrine was the only drug used in large quantities for the suppression of malaria in the SouthPacific Area. Its value was established slowly and with difficulty. At thebeginning of the campaign, little was known about its absorption, blood concentration,excretion, or toxicity. Throughout 1942 and 1943, there was disagreementand uncertainty regarding its use and dosage. Standard treatises upon malariawarned that Atabrine had a small margin of safety and that individuals receivingthe drug should be under close observation.
Administration ofthe drug was frequently begun on shipboard as troops approached malarious islands, and seasickness, diarrhea, and emotional states were sometimes attributedto this drug. The yellow discoloration which it gave to the skin, althoughharmless, gave rise to the suspicion that Atabrine was injurious to the liver,and this rumor was intensified when epidemics of jaundice occurred amongtroops taking the drug. The rumor that Atabrine caused sterility was commonand was fostered by the enemy through the broadcasts of "Tokyo Rose." Thefact that this was effectively disproved by men of units sent for rehabilitationto populated areas did little to improve Atabrine discipline in forward areas.Added distrust of the drug arose when troops who supposedly were taking therecommended suppressive dose developed malaria. There was wide divergenceof opinion among the medical officers of the Marines, who assaulted Guadalcanalin August 1942, regarding the value and the dangers of Atabrine as a suppressivedrug. Some units took quinine, others took Atabrine, and many took nothing.There was no method such as was subsequently developed to supervise the administrationof suppressive therapy.
The directives fromthe theater surgeons office on the subject of suppressive Atabrine therapyillustrate the growth in knowledge of and confidence in this drug as thecampaign progressed. The first such directive appeared in August 1942 andis quoted in part as follows:
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Malaria Prophylaxis
It is recommended that malaria prophylaxis be given as follows: Atabrine is the drug of choice. It should he given in doses of 0.2 grams twice weekly (0.4 grams per week). When it is used, It is to be considered advisable, after 3 months, because of slight cumulative effect of the drug, to substitute quinine for a period of 1 month. Quinine is given prophylactically in doses of 15 grains daily. This should be continued for one month and then Atabrine * * * resumed.
In October 1943, a new directive maintained the suppressive dose of Atabrine at 0.4 gm. perweek, but the schedule was changed so that the drug was taken in one-half tablet (0.05 gm.) amounts per day on each day of the week except Sunday, whenone tablet (0.1 gm.) was taken. In January 1944, the weekly suppressive dosewas increased to 0.6 gm. per week, given in amounts of 0.1 gm. each day exceptSunday. In November 1944, the final theater directive 21 on thissubject increased suppressive doses of Atabrine to 0.7 gm. per week, 0.1gm. to be taken daily.
Results
The value of Atabrine as a suppressive drug was gradually established by clinical observations madewithin the theater at a time when the studies on absorption, blood levels,and excretion were not yet available. It became apparent that a few heavilyseeded units which had good Atabrine discipline were suppressing a largeshare of their malaria as long as they continued to take the drug. Thus,the 6th Marines reported less than 250 cases of malaria while on suppressivemedication during January and February 1943 on Guadalcanal, as compared withover 2,500 cases in May and June after they had moved to New Zealand andhad discontinued the drug. This organization of approximately 4,500 men wason Guadalcanal during the height of the malaria epidemic, was in severe combat,and had fewer cases of malaria than any other organization of equivalentsize exposed in this area at the same time. Every man in this organizationwas given Atabrine under supervision and with the use of a checklist roster.Loading doses of the drug were given before arrival on Guadalcanal and 0.6gm. per week while there. This dosage was given at a time when the theaterdirective called for 0.4 gm. per week. The regimental surgeon reported noevidence of toxicity due to the drug.
The 147th Infantry Regiment took suppressive medication in dosage of 0.4 gm. with poor to fairsupervision from December 1942 through April 1943 on Guadalcanal and hada malaria rate during these 5 months which ranged around 1,000 per 1,000per annum. This rate promptly rose after discontinuation of Atabrine in nonmalariousSamoa to an average of over 3,000 per 1,000 per annum for 5 mouths with peaksas high as 14,000 per 1,000 per annum in selected groups. Atabrine was thenresumed with excellent supervision, and the rate dropped abruptly to wellunder 100 per 1,000 per annum.
21 Memorandum 183, Headquarters, South Pacific Base Command, 1 Nov. 1944, subject: Suppressive Treatment of Malaria.
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Toxicity. - Temporary and minor gastrointestinal symptoms were not uncommon when Atabrinewas first taken. Information regarding this possibility was publicized indirectives and in educational material. It was recommended that medication for such individuals be continued in lower dosages for a brief period and that the full dosage be resumed as soon as possible. Less than 1 person in1,000 developed toxic symptoms from the prescribed dosages. A few cases ofskin lesions which simulated lichen planus pigmentation of the palate andsubungual tissues 22 in those who took suppressive Atabrine forlong periods was noted. Severe toxic manifestations including exfoliative dermatitis, hepatitis, and nervous symptoms such as confusion states were quite rare among those who took only the prescribed dose of 0.7 gm. weekly.
Research, education, and discipline
The careful studies and blood Atabrine determinations of Schaffer and Lewis 23 showed that the development of clinical malaria in troops who were supposedly takingAtabrine in suppressive doses was associated almost invariably with extremelylow blood levels. These workers came to the opinion that a low Atabrine bloodlevel was almost always due to laxity in taking the prescribed medication.They were able to confirm this by careful supervision of Atabrine administrationwith resultant rise in serum concentration and concurrent decrease in malariarelapse rate. Most important of all, they developed a technique which wascapable of convincing the most skeptical line officer of the fact that atightening up of Atabrine discipline would quickly reduce the malaria ratesamong his men.
Administration ofAtabrine for suppressive purposes was ordered to be by roster for both officersand men. An officer or a noncommissioned officer was detailed to watch theactual swallowing of the drug by each individual. Precautions were takento see that individuals who were not present were required to report andto take their medication under supervision. As already noted, the final directiveon suppressive medication ordered a dosage of 0.7 gm. weekly given as 0.1gm, daily. An alternative procedure was undertaken by the 25th Division duringthe latter part of 1944; the drug was given on 2 days a week in doses of0.4 and 0.3 gm. The administrative problem was lessened and suppression appearedto be adequate.
Many men became adeptin circumventing these directives by palming the drug or tucking the tabletsbetween teeth and cheek. Administration by roster did eliminate much of this,but the only adequate solution was an educational program to impress eachman with the value of the drug and with its harmlessness.
22 Lippard, V. W., and Kauer, G. L., Jr.: Pigmentation of the Palate and Subungual TissuesAssociated With Suppressive Quinacrine Hydrochloride Therapy. Am. J. Trop.Med. 25: 469-471, November 1945.
23 Schaffer, A. J., and Lewis, R. A.: Atabrine Studies in the Field; I. The Relation ofSerum Atabrine Level to Breakthrough of Previously Contracted Vivax Malaria.Bull. Johns Hopkins Hosp. 78: 265-281, May 1946.
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Discontinuance of Atabrine suppressive therapy
Atabrine suppressive therapy was discontinued in lightly seeded troops throughout the South PacificArea as control measures became adequate to permit doing so without dangerof significantly increasing malaria rates. This policy was initiated on Efatein September 1942 at a time when the malaria rate had fallen to 144 per 1,000per annum from a peak of nearly 2,700 per 1,000 per annum during the previousApril (table 61). Malaria rates in these heavily seeded troops rose rapidlyduring October and November, and suppression was resumed in all except afew uninfected organizations. This evidence against the blanket discontinuationof suppression in heavily seeded troops was strengthened during the nextfew months by such experiences as noted previously with the 6th Marines andthe 147th Infantry.
These experiences resulted in the following prerequisites for the discontinuation of suppressive medication in malarious territory:
1. Anopheline breedingmust be adequately controlled on the occupied portion of the island and alsoin any areas which the particular organization might enter for training orother activities.
2. Troops must be unseededor lightly seeded with malaria. This was determined by the history of previousexposure and by a study of the malaria rates of each organization. Thoseunits with a history of a high malaria rate were rarely recommended for discontinuationof suppression even if their rates fell to low levels under suppressive therapy.Occasionally, medication would be discontinued in a small pilot group inorder to determine the degree of seeding in a large organization.
3. Troops were notremoved from Atabrine suppression therapy while ground combat was in progressor was threatened or when they were scheduled for early movement to a combator malarious area.
The final theater directive on this subject is quoted in part:
4. Island commanders are authorized to discontinue Atabrine suppressive treatment in selected "lightlyseeded" units upon the recommendation of the Island malariologist as controlmeasures become sufficiently advanced to permit doing so without interferingwith the military effort.
5. Suppressive treatmentmay conceal the actual amount of infection or the gradual seeding of a unit.Apparent freedom from malaria may lead to a false sense of security and carelessnessin regard to truly preventive measures such as mosquito control and individualprotective measures. Therefore, the eradication of the Anopheles mosquitoand protective measures against it must be continued with unabated energy.
The medical officer of an organization in which Atabrine was discontinued was advised to make an exception of those men known to have had vivax malaria and to continuethem on suppressive medication.
Field Research
It is difficult tomake any clear distinction between the routine daily operations and the investigationalwork that was necessary to initiate a malaria
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control program in the South Pacific. Before occupation of the various malarious bases, there was little concrete information about the problems to be encountered. From the beginning of thework, and almost throughout the period of occupation, there was need forcontinuing investigation of problems that had a direct bearing on the controlprogram. These were usually done piecemeal, either in conjunction with oras adjuncts to the operational routine that became established. Occasionally,late in the South Pacific campaign, it was possible to assign personnel orunits to investigational work for brief periods of time. On numerous occasions,from early 1944 on, it was possible to engage in research work in cooperationwith special teams sent out by NAMRU No.2.
Before occupation by the Armed Forces, only 30 species of mosquitoes were known from the entireSolomon Islands; by the end of the war, 70 species of this group were knownfrom Guadalcanal alone. Practically all detailed information about the mosquitofauna of the South Pacific islands was either acquired or confirmed by entomologistsworking on insect-borne diseases during World War II. Initially, it was necessaryto determine what vector or vectors of malaria were present on each base.The fact that A. farauti proved to be the only important species fromthis standpoint did not lessen the investigational work necessary to establishthis fact. The bionomics of A. farauti were studied in detail. 24 Similar critical studies were made with other species to clarifytheir role in the transmission of filariasis.25 Other field investigationsin entomology were concerned with the hosts of trombiculid mites, the incidenceand species involved in human myiasis, and the distribution and biologicfeatures of various species of flies.
In the field of controloperations, investigations were concerned with the determination of flightrequirements of airplanes for use in aerial distribution of insecticides, droplet size analysis of airplane dispensed DDT, suitability of various typesof hand sprayers, minimum lethal dosages of insecticides under tropical conditions,methods of applying residual type DDT spray to tentage and mosquito bed nets,and use of DDT in area treatment against adult mosquitoes. 26The work accomplished was almost invariably the contribution of a numberof individuals working together for the benefit of the program as a whole.
Parasitologic fieldresearch activities consisted almost entirely of surveys of malaria and filariasisin natives and troops. The results of the malaria surveys have been givenpreviously.
24 Daggy, R. H.: The Biology and Seasonal Cycle of Anopheles farauti on Espíritu Santo, New Hebrides. Ann. Ent. Soc. Amer. 38: 1-13, 1943.
25 (1) Byrd,E. B., and St. Amant, L. S.: Studies on Filariasis. Newsletters No. 14 andNo. 16, August and October 1944, Headquarters, Malaria and Epidemic Control,South Pacific Area. (2) Rieber, R. J.: Studies on Filariasis Transmitted byAnopheles koliensis Owen in a Native Labor Camp on Guadalcanal. NewsletterNo. 26, July 1945, Headquarters, Malaria and Epidemic Control, South PacificArea.
26 Special Report,Lt. John D. Maple, USNR, and Maj. Paul W. Oman, MC, dated 27 Nov. 1944, subject:Use of DDT in Area Treatment Against Adult Mosquitoes.
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OTHER ACTIVITIES OF THE ANTIMALARIA ORGANIZATION
The Malaria and InsectControl Organization eventually engaged in a wide series of activities whichgrew out of the technical abilities of its personnel, especially those ofthe parasitologists, engineers, and entomologists. Most of these additionalactivities were concerned with the control of arthropodborne diseases, althoughthere were occasional ramifications such as the campaign to exterminate rats,not only to destroy rats as hosts of the mite of scrub typhus but also becauseof the rats economic depredations. The activities to be described brieflywere usually carried on concurrently with malaria control work. Malaria wasa year-round problem on the malarious islands of the South Pacific.
Dengue fever reached epidemic proportions on the Fiji Islands, New Caledonia, Efate, Espíritu Santo, and Tulagi-Florida Islands, in 1942-43. On Espíritu Santo alone,it caused illness in over 25 percent of the military population and resultedin over 80,000 sick days between January and June 1943.27 Malariatended to obscure the importance of this disease; actually, dengue occurredin sharper outbreaks and with a greater temporary disability to a militaryforce than any other arthropodborne disease. Although the seriousness ofmalaria transmission was usually obscured by the use of suppressive medication,there was no such drug to blunt the immediate effect of a severe outbreakof dengue. Local malaria control groups had given repeated warnings of thepotential hazard of tin can dumps and of other breeding places of the dengue-transmittingmosquito, Aedes aegypti. With the outbreak of these epidemics, themalaria control organization was given adequate authority, personnel, andequipment to cope with the problem. As a result, there was no dengue outbreakin 1944 on any base except in New Caledonia where it was held to very smallproportions.
A severe outbreak of filariasis in the Samoan defense area led to the medical evacuation ofmany thousands of troops engaged in garrison and training activities. Studiesmade during this epidemic demonstrated that the disease syndrome called "mumu"by the natives was an early manifestation of infection by W. bancrofti.This syndrome was characterized by localized swellings, retrograde lymphangitis,lymphadenitis, and genital manifestations. 28
27 Stewart, F. H.: Dengue Analysis of the clinical syndrome at a South Pacific Advance Base. U.S. Navy M. Bull. 42: 1233-1240, June 1944.
28 (1) Dickson,J. G., Huntington, R. W., Jr., and Eichold, S.: Filariasis in Defense Force,Samoan Group; Preliminary Report. U.S.. Navy M. Bull. 41: 1240-1251, September1943. (2) Fogel, R. H., and Huntington, R. W. : Genital Manifestations ofEarly Filariasis. U.S. Navy M. Bull. 43: 263-270, August 1944. (3) Englehorn,T. D., and Wellman, W. E.: Filariasis in Soldiers on an Island in the SouthPacific. Am. J. Med. Sc. 209: 141-152, February 1941. (4) Huntington, R.W., Jr., Fogel, R. H., Eichold, S., and Dickson, J. G.: Filariasis AmongAmerican Troops in a South Pacific Island Group. Yale J. Biol. & Med.16: 529-537, May 1944. (3) Thompson, K. J., Rifkin, H., and Zarrow, M.: EarlyFilariasis in Young Soldiers; Clinical and Pathologic Analysis. J.A.M.A.129: 1074-1079, December 1945. (6) Byrd, E. E., St. Amant, L. S., and Bromberg,L.: Studies on Filariasis in the Samoan Area. U.S. Navy M. Bull. 44: 1-20,January 1945.
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It was discovered that A. farauti. the chief vector of malaria in the Solomons and NewHebrides, was also the most important vector of filariasis in these islands. 29Anopheles koliensis was also found to be a vector of filariasison Guadalcanal. Thus, the exercise of malaria control on these islands hadfortunately furthered the control of filariasis.
The outbreak of tsutsugamushidisease (mite-borne typhus) on Bougainville in 1944 resulted in making thelocal malaria control organization responsible for preventive measures, includingrodent control and the impregnation of clothing with dimethyl phthalate.Study of this disease and its control was aided by the arrival of an advancegroup from NAMRU No. 2. Over 75 cases of tsutsugamushi disease occurred onBougainville, 49 of which were reported by Anderson and Wing.30
Rodent control mas undertaken both to prevent economic loss from rats and to prevent spreadof epidemic diseases which were harbored or transmitted by rats or theirectoparasites. An officer qualified as a mammalogist or with civil experiencein rodent extermination was appointed as rodent control officer and attachedto the Malaria and Insect Control Group at each large base. An adequate numberof enlisted men, equipment, and transportation were provided. A manual wasprepared, men from each military unit on the island were trained in the techniqueof rodent extermination, and their work was then supervised. Fumigation ofships for rat extermination was done on request.
