CHAPTER X
The Southwest Pacific Area
Thomas A. Hart, Ph.D., and Col. William H. Hardenbergh, MSC, USAR (Ret.)
Malaria was one ofthe chief medical and military problems for U.S. Army troops in SWPA (Southwest Pacific Area) during World War II. Until the middle of 1943, malaria incidence was so great that it seriously handicapped military operations. Duringthe 6 months from October 1942 to April 1943, there were approximately10 times as many hospital admissions for malaria as for battle casualties,and a majority of the Allied divisions in the theater were incapable ofeffective military use.1 The malaria incidence reached its peakin February 1943; 2 after February of that year, there was asteady decline due, primarily, to the creation and the operation of an effectiveantimalaria organization. Despite the fact that military operations continuedthroughout the war in areas where the disease was highly endemic, malariadid not thereafter handicap military operations. The organization createdin 1943 functioned effectively in malaria control throughout the remainderof the war in the Southwest Pacific.
A most important aspect of the problem of malaria control in SWPA was that any measures taken had to be applicable to an Allied force, not merely to the U.S. Army. Particularly in the first 2 years of this theater's experience, most bases in malarious areas contained U.S. Army, Australian Army, Australian Air Force, and often Navy detachments of both countries. Uniformity of area antimosquito measures and uniformity of malaria discipline of troops were found to be essential.
At the outset of World War II knowledge regarding the prevention of such endemic diseases as malaria was available and the U.S. Army had had experience in the malarious areas of the Philippines and in Panama, but the mechanics and procedures for the protection of large bodies of troops in highly endemic areas had not been developed. Combat commanders were very slow to recognize the scope of the problems and to heed medical advice for carrying out protective procedures. Blame for the high noneffective rate was often placed on the unit surgeons. Many or most of these had never seen a case of malaria, even in medicalschool, and in addition, they did not have the authority to enforce adequateantimalaria measures, even in their own units.
1War Department Circular No. 223, 21 Sept. 1943.
2 Monthly Progress Report, Army Service Forces, War Department, 31 July 1944, Section 7: Health, p. 10.
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Another early handicap was the policy of the combat commanders that orders should not be explained to the troops. Since, under the conditions existing in this theater, troop education and cooperation were essential, no adequate program of malaria control could at first be enforced. In addition, unit commanders in theearly days of the war often flagrantly disregarded such malaria controlorders as those requiring the wearing of shirts and leggings during certainhours, thereby making enforcement of such orders practically impossible.
After the evacuation of the Philippines, the Australian mainland was organized as a base for the campaign northward. In 1942, the military organization of SWPA provided for seven base sections and one advanced base section. The seven base sections were all in Australia. with headquarters as follows: Base Section 1, Darwin; 2, Townsville; 3, Brisbane; 4, Melbourne; 5, Adelaide; 6, Perth; and 7, Sydney. The advance base section included New Guinea and adjacent territory. The first sizable complement of U.S. troops arrived in four transports in December 1942.
Many of these troops had been serving in malarious areas, and there were numbers of cases ofmalaria among them. Though malaria was not a problem of much magnitude inAustralia, the entire Queensland littoral was infested with anophelines.In many localities, a local endemic was readily possible if the reservoirof infection were sufficiently great. Actually, the problem was treatedby the Australian Government as a major one, and involved all troop and individualassignments to the Northern Territory especially, throughout the first 2years of the war. The protection of Australia against malaria was one facetof a broader problem; that is, the logical insistence of the AustralianGovernment on the protection of Australia against introduced tropical diseases,as well as smallpox. Regulations governing the introduction of malaria-infectedtroops into potentially malarious areas were enforced, and extensive measureswere taken in Townsville and south of Townsville to control mosquitoes inthe environs of American hospitals. By cooperation with Australian healthauthorities and through medication, the threat imposed by the arrival ofthese infected troops was controlled.
Because malaria wasnot common in Australia, few cases were reported among troops stationed onthe mainland--probably not more than 12 cases during 1942, all north of Townsville.There were a good many cases reported in base sections, but practically allwere among troops or patients transferred from New Guinea.
Meanwhile, malaria incidence was increasing among troops in New Guinea. The rate rose in close correspondence with the movement of troops to New Guinea. The malaria rate for New Guinea in October 1942 was less than 200 per 1,000 men per annum, and, for this theater as a whole, it was about 40. In
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December 1942, the rate for New Guinea increased to nearly 600 and for the entire theater to approximately 250. 3
Thus, during the closing days of 1942 and the early part of 1943, malaria had shown itself to be a very serious threat to the success of our military operations in the Southwest Pacific. It was realized also that the problem would be intensified as more troops moved northward into more highly malarious areas. The U.S. Army in this theater lacked the three necessities to conquer the problem: (1) A full appreciation 'by the various commanders of the nature and scope of the problem and of the part that they must play in controlling it; (2) an organization, adequate in skill and in authority, to control malaria; and (3) adequate antimalaria supplies in the forward areas, due to failure of the theater at first to assign necessary priorities of shipment from the United States and locally.
AREA CHARACTERISTICS
New Guinea
Physiography . - The island of New Guinea is roughly 1,500 miles long and 400 miles wide. A massive mountain backbone runs centrally along its length. Although the western tip of the island lies on the Equator, many peaks are snowcapped throughout the year.
South of the central mountain range is a vast low flatland, honeycombed with rivers, swamps, and high rain forest jungle. The southern coast for the most part is lined with impenetrable mangrove swamps, backed up inland by broad nipa palm swamps. Other inland swamps are covered with grass several feet high (kunai grass) and, when viewed from the air, appear to be grassy plains (fig. 56).
North of the central range are parallel mountain groups lying along the coast. The fertile inland valleys are drained by large rivers, such as the Fly, Mamberamo, Sepik, Ramu, and Markham. Swamps are found along the upper reaches of these rivers, and at their mouths.
The mountains are covered with dense tropical rain forest. Secondary growth of tall grasses and scrub replace forests which have been burned off in the valleys and plains to provide land for temporary cultivation. Although some areas have been planted with rubber and coconut trees, less than 1 percent of New Guinea is under cultivation.
Along the coast, there is little variation in temperature and humidity. The temperature averages 80° F., with local means rangingfrom 77° to 83 ° F. The humidity averages 85 percent, with local means ranging from 70 to95 percent. Above 2,000 feet, temperate climates are encountered.
3 Monthly Progress Report, Army Service Forces. War Department, 31 July 1943, Section 7: Health, p. 6.
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The annual precipitation ranges from about 40 inches per year at Port Moresby to over 300 inches in the mountains. The season of maximal rainfall also varies from place to place. This seasonal variation is due to the two monsoons (northwest monsoon--November to May; southeast monsoon--May to October) and to the particular exposure or lack of exposure of various areas to these monsoons. Generally speaking, the heaviest rainfall occurs on the windward side of the mountain wherethe rain clouds are trapped.
Malaria is hyperendemic in coastal areas and at altitudes up to 2,000 to 3,000 feet.
Since there are dailyrains in many areas even during the "dry" season, mosquito breeding and malariatransmission may continue throughout the year, but there is an increasedincidence at the beginning and end of the rainy season. Where the soil issufficiently porous, breeding places may exist only during the season ofheaviest rains.
Wherever surface water drainage is poor because of high subsoil water level or nonporous soil, mosquito breeding is most prolific. This is especially true in river valley lowlands and in coastal swampy areas. The habits of the two important malaria vectors are such that the mosquitoes take quick advantage of manmade breeding places. This explains the occurrence of "manmade malaria" in this area.
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Falciparum malaria prevails on New Guinea, although there is considerable variation from place to place. Vivax malaria is also common. Quartan malaria is seen infrequently, but a small focus existed at one time between Morobe and Buna on the Mambare River.
The clearing of vegetationfor camp and airfield construction is likely to be attended by a sudden increaseof malarial vectors, which are sunlight breeders, unless special care istaken to minimize the occurrence of artificial depressions in which theymay collect (map 30).4
Range of malaria . - In New Guinea, malaria is endemic to hyperendemic throughout thecoastal district and the smaller islands. In areas with well-marked dryseasons, such as Port Moresby, which are exposed to the full force of thesoutheast trade winds, on the south coast of New Guinea, malaria shows amarked seasonal incidence, with transmission being at its maximum shortlyafter the end of the wet season and minimal or absent during the later partof the dry season. In more sheltered situations, transmission is perennial,though it may fall off when the breeding grounds are flushed out by heavystorms during the summer. Malaria appears to be absent from the higher inlandcountry at an altitude of 3,000 to 4,000 feet or more, but in high altitudes,fatigue and rigors of travel are particularly liable to provoke relapsesof infection contracted on the coast. In limited areas, that is, Port Moresby,Samarai, and Rabaul, a considerable degree of control had been formerly established, but it had lapsed with the Japanese invasion. Even in the Port Moresby area, though there had been much work done for malaria control, the Australian troopsstationed in that area from January to June 1942 suffered an infection rateof approximately 50 percent. 5
Vivax, falciparum , and quartan malaria are all present in New Guinea, the proportionsvarying in different areas and in different seasons, but falciparuminfections predominate. The effect of malaria is greatest among newlyarrived Europeans, and high mortality and morbidity rates are encounteredamong them. The arrival of Europeans in a given area is usually followedby an increase in the virulence of the disease, and in turn this increasedvirulence adversely affects the nonimmune native population. In 1940, between14 and 19 percent of all European hospital admissions were for malaria andblackwater fever. The spleen rate among the natives was between 25 and 30percent, but in some regions, almost 100 percent of the natives had malaria.The peaks of the malaria season usually occur in January and February, andin May and June.. The spleen indices in the various districts of the NewGuinea mainland (1936-37) were as follows: Sepik District: 43.1; MadangDistrict, 33.4; and Morobe District, 25.3. Occasional cases of blackwaterfever are observed, particularly among the Europeans.
4 Health and Disease in New Guinea. Arctic, Desert and Tropic Information Center; Regional Medical Studies, April 1944.
5 Report. Maj. I. M. Mackerras, Medical Entomologist, Australian Army, Notes on Mosquito-Borne Diseases in Australia, 1942.
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Malaria is also widelydistributed throughout Papua and the adjacent group of islands. Along thegreater part of the coastal region of Papua, as well as in most of the islands,malaria is hyperendemic. The incidence of the disease is also high in thecentral highlands of the mainland. In the mountainous country above 2,000feet, it falls to a minimum. The malaria problem in Papua is essentially the same as in the Territory of New Guinea, with the notable exceptionof Port Moresby. At Port Moresby, there is a well-marked dry season fromMay to January, with only about 30 inches of rain per year, and thoughthe incidence of malaria is high in this region, there is a notable dropduring the latter half of the dry season. Malaria is hyperendemic in theisland groups of D'Entrecasteaux and Amphlett. It is highly endemic in theTrobriand Islands, the Louisiade Archipelago, and the Woodlark Islands
The mainland of NewGuinea, and its outlying islands, will be considered in more detail under the following divisions:
1. The Mandated Territory of New Guinea and its associated islands.
2. Papua and its adjacent islands.
3. NetherlandsNew Guinea.
The MandatedTerritory of New Guinea
The territory includes, in addition to a large area on the New Guinea mainland, the islands ofNew Britain and New Ireland, the Admiralty Islands (Manus), Bougainvilleand Buka in the Solomon Islands, and numerous smaller islands.
Malaria is prevalent throughout the Territory--in many parts, especially in the coastal regions, it is highly endemic or hyperendemic.
It is reported that at Kokopo near Rabaul (New Britain) 62 percent of the European morbidity was caused by malaria, with many cases of blackwater fever.
A large part of theinfant mortality is, directly or indirectly, due to malaria, and it appears to be one of the main factors in the depopulation of certain parts of Melanesia.
Except in limited areas, as at Rabaul and the larger settlements where the control of vectors has been effective, new arrivals are usually quickly infected.
Splenic indices .- Patrol reports in 1934, covering the examination of 22,000 natives, showed the average spleen rate in children to be 30 percent for the Territory generally.
The following splenic indices are for the greatest part examinations made in 1936-37, thougha few are from earlier reports:
New Guinea mainland: Splenic indices
Sepik district....................................................................................... 43.1
Madang district................................................................................... 33.4
Morobe district................................................................................... 25.3
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New Britain: Splenic indices
Gazelle Peninsula................................................................................... 23.1
Talasea district...................................................................................... 40
Walonga district.................................................................................... 52
New Ireland:
Kavieng district..................................................................................... 34.3
Namatanai district..................................................................................32.1
Solomon Islands
Kieta.................................................................................................... 63.2
Buka Passage....................................................................................... 24.7
Duke of York Group................................................................................ 56
Admiralty Islands:
Manus.................................................................................................. 53
Relative frequency of parasites. - Falciparum, vivax, and quartan parasites are found, the proportions varying in different areas and at differentseasons. Since many reports of relative parasite frequency are gatheredfrom examination of hospital patients, it would appear that, in these patients,the reported frequency of falciparum may be higher than that prevailingamong the general population, as this type more frequently requires hospitaltreatment.
Examinations at theRabaul Laboratory (1935) showed the following relative frequencies for whitesand natives:
Whites: Relative frequency
Plasmodium falciparum......................................................................... 76
Plasmodium vivax.................................................................................. 24
Quartan................................................................................................... 0
Mixed...................................................................................................... 0
Natives:
Plasmodium falciparum.......................................................................... 68
Plasmodium vivax.................................................................................. 21
Quartan.................................................................................................... 4
Mixed....................................................................................................... 7
The variation in the relative frequency of parasites in different areas can be seen in the results of surveys conducted in the North Coast and the Duke of York Group.
North Coast: Relative frequency Parasite rate
Plasmodium falciparum......................................................................... 75 13
Plasmodium vivax.................................................................................. 25 --
Quartan.................................................................................................... -- --
Mixed...................................................................................................... -- --
Duke of York Group: 58
Plasmodium falciparum......................................................................... 40 --
Plasmodium vivax................................................................................. 21 --
Quartan................................................................................................... 21 --
Mixed..................................................................................................... 18 --
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In New Ireland, quartanmalaria has not been found. Falciparum malaria is more common thanvivax, and mixed infections are not rare.
Blackwater fever. - A number of cases of blackwater fever are reported each year. Administration records for 1936--37 show 12 cases with 3 deaths. The incidence is lessthan in the early days of the Morobe goldfields, when a poorly nourishedEuropean population suffering from neglected malaria was engaged in veryhard physical labor. Any alteration in circumstances which tended to producesuch a combination of conditions resulted in a fatal outbreak of blackwater.
Seasonal prevalence of malarial attacks. - Heydon, at Rabaul, found that in white residents the maximum of malarial attacks occurred in January and February and in May and June, with the minimum in September and October. He considered that the height of the May-June rise might be due to the cooler weather disposing to relapses.
Positive blood examinations in Rabaul also showed a minimum toward the end of the dry season and amaximum about May. The latter rise was due to falciparum infections.
Brennan, in 1935, considered that there was a variation in virulence of falciparum strains endemic in various parts of the Territory. Cases of falciparum malaria contracted in some parts were munch more severe than those in others. This severity was quite independent of the number of parasites present in films.
Australian Papua
Papua and its adjacent islands. - The Australian Territory of Papua comprises the large area in the southeastern part of the New Guinea mainland, and the great island archipelagoes scattered to the east--the Louisiades, the D'Entrecasteaux group, and the Trobriand Islands.
Malaria is hyperendemic in a great part of the coastal region of the mainland, as well as in a large number of the associated islands. The incidence is lower in the central highlands of the mainland and falls to a minimum in the mountainous country above 2,000 feet.
The Port Moresby area differs sharply from the rest of the island in that it lies within a small "rainshadow" zone, with only about 30 inches of rain per annum, with a well-marked dry season from May to January, and with climate and vegetation resembling those of northern Australia rather than the rest of the island. Nevertheless, there has been a high rate of malarial infection both inthe natives formerly present and, more recently, in the troops stationedthere. The climate peculiarities of this area are, however, of considerablepractical importance, for it is likely that transmission of malaria doesnot occur during the latter half of the dry season.
In the mountainous D'Entrecasteaux group, every island is subject to hyperendemic malaria. The population (about 25,000 natives) practically all live on the narrow, low-lying coastal fringe of the large islands where
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anopheline vectors breed freely. All newcomers are infected, and black-water fever and malignant cerebral forms have been common among the few white residents. Habitation ceases at about 2,000 feet, for the mountain slopes above that level are infertile, buthigh spleen rates are encountered to that limit.
The Amphlett Group, a cluster of small steep-sided and rocky islands to the northeast of Fergusson Island (D'Entrecasteaux), also shows hyperendemic malaria in the scattered villages which nestle at the base of the cliffs. Here, anophelines breed freely in pools and soakages.
In the Trobriand Islands (Kiriwina, Kitava, Kaileuna, and Vakuta), malaria is endemic throughout, but does not reach the rates of the neighboring D'Entrecasteaux group. The spleen rates in children are in the vicinity of 10 percent in most villages, rising to a maximum of 30 percent in a few places.
The small island of Samarai, the administrative station for the eastern division of the Territory of Papua, has, by assiduous control measures, been entirely freed from malaria. The close-lying heavily wooded islands, the Rogeia, Sariba, and Basilaki, outside the sphere of this control, however, are malarious (splenic indices--Rogeia 48, in 1938). The neighboring part of the mainland, the Milne Bay area,is also hyperendemic and was regarded by oldtimers of Papua as one of theworst malarial areas in the eastern division. Splenic indices of 71, 80,and 98, respectively, were found in three villages on the swampy southernshoreline of Milne Bay and of 56, in a village near East Cape. At Buna onthe northeastern coast, the disease is also hyperendemic, a splenic indexof 68 being reported. In both the coastal area of this eastern extremityof the New Guinea mainland and the neighboring islands, black-water feverand cerebral malaria have taken a heavy toll of the scanty white population.
In the scattered islands of the Louisiade Archipelago, malaria is endemic throughout. At Misima, the main island of the group, for many years there has been a large concentration of native laborers employed in the mining industry. These laborers have been brought from various parts of the Territory, with the consequent introduction of new strains to an island which already shared the high malarial incidence of the new group.
At Woodlark Island (Murua), malaria is also present. The island is heavily wooded, the lower parts with thick mangrove. The rainfall is heavy, but the higher ground is well drained, and malaria is said to be consequently rarer on the higher parts, though prevalent at Bonagai, the post on Kwaiapan Bay.
Netherlands New Guinea
Netherlands New Guineacomprises a few small scattered settlements along the coast, and large tractsof unexplored territory in the interior of the island, inhabited only byuneducated savages. There has never been any well-
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integrated health organization, and information concerning disease is scanty. Before Japanese occupation, there were six government-paid physicians on the island located at Merauke, Fakfak, Manokwari, Hollandia, Sorong, and Wissel-meren. In addition to practicing curative medicine, these doctors cooperated with local civil authorities to enforce elementary sanitary measures in their areas. These physicians were responsible to the health officer in Amboina, who, in turn was responsible to a regional officer in Makasar. This officer was responsible to the head of the Public Health Service of the Netherlands East Indies in Djakarta.
The prevalence of malaria in the coastal regions can be ascertained to some extent from surveys in which the splenic indices of natives in many small villages were obtained (table 73).
TABLE73.- Splenic indices in natives of Netherlands New Guinea
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TABLE 73.- Splenic indices in natives of Netherlands New Guinea -Continued
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The entire northern coast and the southern coast of Vogelkop are highly endemic areas. The vectors most frequently found are A. punctulatus and Anopheles farauti. Anopheles bancrofti Giles is not found on the northern coast. On some parts of the southern coast (between Kaimana and Atoeka), owing to the great height of tides, there are no suitable breeding places for mosquitoes, and some villages are nearly free of malaria. In the Merauke area, perhaps owing to the existence of a definite dry season between June and December, theincidence of malaria is low, although A. farauti breeds there inlarge numbers during the rainy season. In the Mamberamo River valley, malariais highly endemic. Tanahmerah, in the southern part of the island, was formerlya highly endemic area, but in recent years, the Dutch authorities had reducedthe incidence of the disease. Mountainous areas are not necessarily freefrom malaria since A. farauti has been reported at heights of 3,500feet. However, there is very little malaria in the Zwart-vallei (3,500 feethigh). An exploration party in the southwestern part of the central mountainsof New Guinea remained for months completely free from malaria.
All three forms ofmalaria are found, but vivax malaria is by far the most common, representingprobably from 75 to 80 percent of malarial infections among natives at Manokwari,Seroei, and Babo.6
The Philippines
The more than 7,000 islands of the Philippines may be grouped into four main divisions. Eleven of the largest islands constitute more than 94 percent of the total area; only 2,441 of the islands have names. The islands extend 1,152 miles north and south and 688 miles east and west. The combined land area is 115,000 square miles. The climate is distinctly tropical. The average rainfall is 93 inches.
The climate of the Philippines is hot and moist. Average temperatures are in the neighhorhood of 80 0 F., and the words "summer" and "winter" have little meaning. The difference between the highest and lowest monthly averages at coastal stations is usually only a few degrees, and is seldom as great as 10 degrees. Inland stations, at a higher elevation, are much cooler than those on the coast, and have a smaller annual range. The seasonal distinctions in thePhilippines depend on precipitation rather than on temperatures and separatethe year into a dry season and a wet season, with the difference betweenthe two periods decreasing toward the south and east. Seasonal wind shiftsor monsoons (northeast in winter and southwest in summer) cause the wet anddry seasons to occur at different times on the east and west coasts. Theeast coasts have their rainfall maximums in winter (October to January) anda relatively poorly defined dry season in early summer. West coast stations have
6 War Department Technical Bulletin (TB MED) 18, 10 Mar. 1944
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a pronounced wet period in summer and a dry period in winter. In the extreme south (Davao, Mindanao), there is a double maximum of rainfall, May or June, and October. Typhoons occur most frequently between July and November and often do great damage becauseof their force and the torrents of rain which may accompany them.
Thirty-two species of anopheline mosquitoes have been recognized in the Philippines as follows:
1. A. aconitus Donitz 1902 18. A. leucophyrus leucophyrus Donitz 1901
2. aitkenii James 1903 19. leucophyrus riparis King and Baisas 1936
3. aitkenii begalensis Puri 1930 20. lindesayi benguetensis King 1932
4. annularis Van der Wulp 1884 21. litoralis King 1932
5. baezai Gater1933 22. ludlowi Theobald 1903
6. barbirostris Van der Wulp 1884 23. maculatus Theobald 1901
7. cristatus King and Baisas 1936 24. mangyanus Banks 1906
8. filipinae Manalang 1930 25. minimus flavoristris Ludlow 1913
9. gateri Baisas 1936 26. nigerrimus Giles 1900
10. gigas formosus Ludlow 1909 27. paragensis Ludlow 1914
11. hyrcanus pseudosinensis Baisas 1935 28. philippinensis Ludlow 1902
12. insulaeflorum Swellengrebel and Swellengrebel de 29. pseudobarbirostris Ludlow 1902
Graaf 1919
13. karwari James 1903 30. subpictus indefinitus Ludlow 1904
14. kochi Donitz 1901 31. tessellatus Theobald 1901
15. kolambuganensis Baisas 1932 32. vaug limosus King 1932
16. lesteri Baisas and Hu 1936
17. leucosphyrus balabacensis Baisas 1936
On the basis of accumulatedevidence, only four species of anopheline mosquitoes have been blamedin the transmission of malaria. The most active transmitter is Anophelesminimus flavirostris, a member of the funestus-minimus subgroup. The other two members of the subgroup, Anopheles mangyanus and Anopheles filipinae are of secondary importance. Anophelesmaculatus is a doubtful vector. Anopheles flavirostris is a streambreeder, definitely preferring clean, fresh, flowing and slightly shadywater and with the presence of bamboo shoots or roots. Consequently, malariais a disease of the foothills and is not seen in the lowlands or ricefieldsend does not appear above elevations of 2,000 feet. It was not until thisfact was fully appreciated that any progress was made in malaria control.When there are pronounced wet and dry seasons, malaria will appear in twowaves each year at the change of the seasons. Where such seasons are notpronounced, malaria is perennial. It has been suggested that the prevalence of malaria in the foothills has been partly responsible for the maintenance of ethnologic distinctions between the hill people and those from the plains. 7
7 War Department Technical Bulletin (TB MED) 68, 18 July 1944.
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MEDICALLY IMPORTANT MOSQUITOES OF THE SOUTHWEST PACIFIC
Anopheles
Anopheles amictus Edwards is found in Queensland, northern Australia, and Australian Oceania. Subspecific variants are Anopheles amictus amictus Edwards and Anopheles amictus hilli Woodhill and Lee. Larvae breed in shady or sunny swamps. Anophelesamictus hilli is more often found in brackish water and A. amictusamictus in fresh water. Adults take human or animal blood. Sporozoite-infected A. amictus hilli has been reported from Queensland.
Anopheles annulipes Walker is found in Australia and Tasmania up to 1,200 meters and in Australian Oceania. Subspecificvariants are Anopheles annulipes annulipes Walker and Anophelesannulipes mastersi Skuse. Larvae are found in shallow ground and rockpools, usually in fresh, sometimes brackish water. Adults feed avidly onman. No natural infections have been reported, but the insect has beensuspected in one or two areas.
Anopheles bancrofti Giles is distributed throughout Polynesia, Australian Oceania, northern Australia and Netherlands New Guinea. Subspecific variants are Anopheles bancrofti bancrofti Giles and Anopheles bancrofti pseudobarbirostris Ludlow. Larvae breed inpermanent, still, abundantly vegetated ponds and pools, generally wellshaded. Anopheles bancrofti ordinarily feeds at night but sometimesfeeds avidly on man in the daytime. Oocysts have been found in A. bancroftibancrofti, but no sporozoites have been reported.
Anopheles bancrofti is found in the interior of New Guinea and along the southern coast but not on the northern coast. It is found in large numbers at Tanahmerah, at Kloofbivak on the Lorentz-Rivier, at Merauke, at Etna-Baai, and at Prauwenbivak. An infection rate of 4.3percent was reported at. Tanahmerah.
Anopheles farauti Laveran 1902 is found in the coastal areas of Moluccas east to New Hebrides and south to 200 south latitude. Synonyms are Anopheles punctulatus farauti Laveran, Anophelespunctulatus moluccensis Swellengrebel and Swellengrebel de Graaf, Anopheles farauti farauti Laveran, and Anopheles farauti moluccensisSwellengrebel and Swellengrebel de Graaf.
Larvae breed in groundpools of all varieties, including pools in sand, muck, coral, tracks of vehiclesand animals; in grassy margins of sluggish streams, mangrove swamps withabundant flotage, and surface wells; and occasionally in brackish water andat times in containers. Anopheles farauti has been reported at heightsup to 3,500 feet. Adults feed on man or animals, attack warily but persistentlyat any time between dusk and dawn, and frequent human habitations.
Anopheles farauti is an important vector of malaria throughout its range and is the only one in the New Hebrides. Numerous gut and gland natural
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infections of A. farauti have been reported with sporozoite indices up to 5 or 6 percent. Anopheles farauti is also an important vector of filariasis in the Solomons and New Hebrides.
Gut and gland infection rates of 13 percent were reported at Tanahmerah. This species is 'the most important vector in eastern New Guinea, the Solomons, and New Hebrides.
In the Philippines, Anopheles maculatus Theobald is found chiefly in clear running water of mountain streams well exposed to the sun, often on an opposite bankfrom A. minimus flavirostris, the latter along a more shady edge.Anopheles maculatus is often found in seepage water, springs, andshallow wells. Adults feed on man and animals and frequent human dwellings.
Anopheles maculatus ranges from Ceylon through India to South China and Formosa, thence south through Malaya and the Philippines to the Sulawesi. Anopheles maculatus is an important vector in Malaya but is of only minor importance in the Philippines and elsewhere in theSouthwest Pacific.
Anopheles mangyanus Banks is found in the Philippines. Larvae breed usually in clear flowing and shaded water. Anopheles mangyanus has been found naturally infected with sporozoites. Anopheles mangyanus is associated with A. minimus flavirostris in the transmission of malaria in the Philippines.
Anopheles minimus flavirostris Ludlow is found in the Philippines and south to Djawa. Larvae breed along margins of clear flowing water, generally somewhat shaded, usually in the foothills, and not above 2,000 feet altitude, and not on the plains more than a mile or sodistant from hills. Adults enter houses at night to feed on man but are oftenfound inside habitations in the daytime. They prefer earthy resting placessuch as undercut banks of streams. Adults take cattle blood readily. Anopheles minimus flavirostris has been found naturally infected in the Philippines where it is the chief vector of malaria.
Anopheles punctulatus Dönitz is distributed throughout Melanesia north to 20 0 south and west to 170 0 east, and west to Sulawesi and northern Australia. Larvae are found primarily in ground pools. Anopheles punctulatus is dominant where soil is heavy clay while A. farauti tends to replace it where the soil is sand or muck. For example, along the sandy coastal strip north of Oro Bay only A. farauti was found but around Milne Bay where there are both clay and sandy areas, both species were found. Pools formed inthe tracks of vehicles and animals were notable breeding places, especiallyaround army camps. Larvae were also taken in bomb craters, hog wallows,intermittent streams, grassy pools, and ditches; more rarely in mangroveand sago swamps, in tin cans, and rarely, in brackish water. Larvae werenot found in tree holes, cocoanut shells, or foul water, as a rule. Adultstake human blood avidly and also animal blood. They frequent human habitationsand feed mostly after 2100 hours. The bite seldom causes irritation.
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Naturally acquired infections in A. punctulatus have been reported from New Guinea, New Britain, and Guadalcanal. Anopheles punctulatus is also a vector of filariasis.
This species was often found in settlements recently cleared of forests but was rarely taken in the Upper Digoel region. In northern New Guinea, infection rates were 1.5 to 5.0 percent.
Anopheles subpictus indefinitus Ludlow occurs in Indonesia to the Sulawesi, in Borneo and the Philippines, in Guam (since World War II), and possibly in Formosa. The form taken in New Guinea and partsof Melanesia may be a subspecific variant. Larvae taken in Melanesia haveoften been found in brackish as well as in fresh water pools, and in marshesand swamps. Adults prefer animal blood but occasionally feed on man. Theform taken in Melanesia and New Guinea may be a secondary vector, as suspectedin Papua, but natural infections were not reported in the Southwest Pacific.
Aedes
Aedes aegypti Linn ranges perennially in the humid parts of the world wherever larva habitats do not freeze. Aedes aegypti is distributed throughout the Southwest Pacific in coastalsections and has sometimes been called the "mosquito of seaports." Larvaeare found in peridomestic containers, such as roof gutters, horse tanks,barrels, bottles, cans, and tire casings, sometimes in leaf axils, rarelymore than 1,500 feet from habitations. Adult has short flight range, ishouse-haunting, and feeds avidly on humans, usually in the daytime. Aedesaegypti is a vector of dengue in the Southwest Pacific and also carriesyellow fever in Africa and South America.
Aedes albopictus Skuse is distributed from Japan south and west to the continent, and eastward through Micronesia to the Hawaiian Islands. Aedes albopictus is a vector of dengue in the Philippines and elsewhere in the Southwest Pacific and resembles Aedes aegypti.
Aedes kochi Dönitz is found in Pacific Oceania. Larvae were taken in the water of plant axils. Adults feed avidly on man at night. Aedes kochi is a suspected vector of filariasis.
Aedes scutellaris Walker has a complex of forms having similar habits and only slight morphological differences. Aedes scutellaris scutellaris Walker is distributed throughout the Philippines and south to New Hebrides but not in the Fiji Islands. Aedes scutellaris pseuodoscutellaris Theobald is found at 175 0 east to 120 0 west longitude and 0 0 to 22 0 southlatitude. Aedes scutellaris polynesiensis Marks is found in the FijiIslands. Larvae occur chiefly in rot holes of trees. In New Guinea and onBiak, however, larvae were found in almost any container not having mudwalls, such as in foul water in canoes, coconut shells, military junk heaps,including paper containers, and in cans with lacquer linings. Adults areday feeders, attacking man freely mostly out of doors but also in tentswhen near breeding places. Aedes scutellaris rest out of doors. Aedes scutellaris pseudoscutellaris and A. scutellaris poly-
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nesiensis are vectors of filariasis in the Fiji Islands, and the closely related A. scutellaris scutellaris may be a vector in New Guinea.
Aedes vigilax Skuse is distributed in the tropics from Formosa to Thailand and east and south to New Caledonia and Australia. Larvae are found in shallow ground pools of tidal flats and in mangrove swamps. Adults are strong fliers. They feed avidly on man at night and early morning but sometimes all day in the bush, and they may evadehouses. Aedes vigilax is a suspected vector of filariasis.
Culex
Culex annulirostris Skuse is found in Melanesia, Polynesia, Papua, and Australia. Larvae are found in ground pools, including those of ricefields and swamps, and in all kinds of domestic containersin urban and rural areas. Adults feed at night on man and animals. Culex annulirostris, experimentally, is a vector of filariasis but is notfound naturally infected in the Southwest Pacific.
The subspecific variantof Culex pipiens Linn, Culex pipiens fatigans Wiedemann, whichis the Culex quinquefasciatus Say of some authors, is found throughoutthe tropical world and was widespread in the Southwest Pacific. Larvae ofC. pipiens fatigans were taken in collections of foul water in groundpools and in domestic and periodomestic containers, usually shaded. Adultsgenerally are strong fliers and feed on man and animals, at night, as a rule.Culex pipiens fatigans is known as an important vector of filariasisin several areas, as in the Philippines, but its role in New Guinea is stilldoubtful.
Culex vishnui is a group of species quite similar in appearance and is distributed in the Orient and in Pacific Oceania. Larvae of the various species are found usually in small pools, drainage ditches, ponds, and streams. Culex vishnui is considered a vectorof filariasis in India but not in the Southwest Pacific.
Mosquito Survey Data
Information on the distribution and bionomics of the mosquitoes of New Guinea and the adjacent islands was materially augmented by the various malaria units. This work was done more or less incidentally to field activities and was handicapped by the lack of suitable minor laboratory supplies and equipment. The paucity of information on the distribution and habits of the principal vector of malaria, A. punctulatus, and of other species that may play a part in the transmission of dengue, filariasis, and other diseases of military importance, was at first a serious handicap to the full utilization of control procedures. In this field, the work of Capt. (later Maj.) William R. Horsfall, SnC, entomologist of the 17th Malaria Survey Unit at Oro Bay, was especially valuable. He and his associates found A. punctulatus in the Markham Valley to range between sea level and 3,800 feet, with very fey on the level coastal
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plains with sandy soil. They were most abundant below 2,000 feet and in areas with impervious soils. Breedingtook place in open or slightly shaded water such as pond and stream margins,wheel ruts, and borrow pits.
Anopheles farauti, on the other hand, was more at home along the coast and in partially shaded situations, as along sluggish streams, and shaded pool margins. When present in limited numbers, adults were not prone to stay in tents or huts but apparently were widely distributed in secluded damp places under vegetation. They were observed in protected places in stream banks, in holes, and in overhanging grass, but alwaysin the general vicinity of camps or native paths or villages.
Captain Horsfall reported that development from egg to adult of A. punctulatus took place in 8 days in warm water (95° F.) in the sun, and from 10 to 14 days in the laboratory. The egg stage ranged from 1 to 6 days in the laboratory arid the larva and pupa stages from7 to 12 days, with an average of 8.5 days. Captain Horsfall also found thatadults traveled freely one-fourth mile, a very few to three-fourths miles.One female lived 17 days. Caged females could not be induced to feed a secondtime and no eggs were laid.
All agree that adults of A. punctulatus fed freely in captivity. In nature they were shy, and produced little or no irritation. This caused men to be careless, as they were not annoyed, and they seldom saw the mosquito.
Anopheles punctulatus was readily infected with either Plasmodium falciparum or Plasmodium vivax. In the experimental work at Cairns, often nearly 100 percent infection of salivary glands was secured, but high natural infection rates were not found. Of 315 females collected near Oro Bay, April and May 1944, Horsfall reported that only6.4 percent showed gut infection, and of 586 salivary glands examined, only0.3 contained sporozoites. These were evidently newly fed. Filarial infestations were found in 9 of 607 females dissected.
Breeding places ofvarious culicine mosquitoes including Aedes scutellaris, which wasevidently the principal carrier of dengue, were very diverse. Stagnant pools,margins of streams, seepage and rainwater in sage and mangrove swamps, leafaxils of trees, coconut shells, and various manmade water containers produceddifferent species in varying numbers. Along the coast, coral pockets weresaid to serve as prolific breeding places for A. scutellaris. 8
There were twenty species and subspecies of Anopheles and seven species of Bironella. Only three of these (Anopheles karwari James, a subspecies of Anopheles subpictus, and A. bancrofti pseudobarbirostris ) were more or less widely distributed in adjacent regions, and the first two at least were possibly introductions into New Guinea.
8 Malaria Report No. 254, Report of the Malaria Mission to the Southwest Pacific Area, 20 Aug. 1944, in Board for Coordination of Malarial Studies, a Joint Body Composed of Representatives of the Office of Scientific Research and Development, the Army, the Navy, and U.S. Public Health Service, and the National Research Council, vol. III. [Official record.]
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The commonest and most widely distributed species in the Australasian Region were A. annulipes, A. punctulatus, and the subspecies of A. bancrofti and A.amictus. Some of the other species were known only from a single localityor had a limited range. The portions of the region from which the different species have been recorded are indicated in table 74.
Anopheles farauti, the form with an all-dark proboscis previously known as Anopheles moluccensis, had the widest distribution (map 31). It was found throughout the islands from eastern Sulawesi to New Hebrides and also occurred in northern Australia, being common at Cairnsand in the Darwin area. There was a single record as far south as the Brisbanearea reported by Lee and Woodhill.9 The type form, A. punctulatusmoluccensis, in which the apical half of the proboscis is largely pale-scaled,was collected in Australia or New Hebrides but otherwise had the same generaldistribution as A. punctulatus. Anopheles clowi Rozeboom and Knight,a recently described species, was found only at Hollandia.
The most widely distributedspecies in the region was A. annulipes, found throughout Australia,in Tasmania, a few localities in New Guinea, and the adjacent island of Goodenough.At Port Moresby, it was the commonest anopheline encountered and was saidto be the dominant species in the greater part of Australia.
The type form of A. amictus was widely distributed in the northern part of the continent and occurred along the eastern coast to northern New South Wales. The subspecies A. amictus hilli had the same general distribution and was foundalso at Merauke in southern Netherlands New Guinea.
The type form of A. bancrofti was widely distributed and frequently very abundantin northern Australia from just north of Broome to Cairns, and along theeast coast to Brisbane. It occurred in Netherlands New Guinea in the Meraukearea and along the Digoel-River. There was a single record from northernNew Guinea, at Pionierbivak, which m ay actually have been the subspecies A. bancrofti pseudobarbirostris. The latter was the form found inthe remainder of the northern and eastern parts of the island, as also onGoodenough Island. Its range extends into the Sulawesi and the Philippines.
The distribution of Anopheles stigmaticus, as given by Lee and Woodhill, is the coastal ranges of eastern Australia and two widely separated localities in New Guinea, one at Bulldog in Papua and the other at Anggi-meer in the northwestern part of the island. Anopheles atratipes Skuse occurred in smallnumbers in the Sydney, Brisbane, and Cairns areas on the east coast andat Perth on the west coast. Anopheles powelli was recorded only fromthe northern portion of Northern Territory and the tip of Yorke Peninsula.
9 Lee, D. J., and Woodhill, A. R: The Anopheline Mosquitoes of the Australasian Region. University of Sydney, Department of Zoology, Monograph No. 2, 1944.
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TABLE74.- Distribution of anopheline species of the Australasian Region
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TABLE 74.- Distribution of anopheline species of the Australasian Region - Continued
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MAP 31.- Distribution of the Anopheles punctulatus series.
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Anopheles meraukensis Venhuis and Anopheles novaguinensis Venhuis both occurred in Northern Territory, in the Cairns area of northern Queensland, and in the Merauke area of southern New Guinea. The former was found also at Townsville and Brisbane, and the latter on the tip of Yorke Peninsula. Anopheles longirostris Brug was recorded from variousparts of New Guinea as well as Seram and Halmahera. An unidentified varietyof A. subpictus was reported in New Guinea only from a few areasalong the southern coast of Papua. The same or similar form is widely distributedin the Netherlands Indies. Anopheles karwari was found in 1945 atHollandia and was taken in considerable numbers in one location. 10 It may have been introduced from adjacent parts of the Oriental regionwhere it is widely distributed.
Belkin and coworkers described in addition to A. punctulatus, three new species, Anopheles lungae,11 Anopheles solomonis,12and Anopheles nataliae.13 The last three species are closely interrelated forms distinguishable principally by variations in coloration of the female proboscis and by larval characters.
The following species were reported only from the Moluccas, Seram, or Timor:
A. aitkeni bengalensis A. insulaeflorum
A. albotaeniatus A. kochi
A. annularis A. maculatus
A. barbirostris A. minimus
A. barbumbrosus A. sundaicus
A. hyrcanus A. tesselatus
A. vague
It is doubtful if the reports of A. tesselatus, A. barbirostris and A. aitkeni from New Guinea, and Anopheles ludlowi from Seram were correct.. Specimens from New Guinea, identified as Anopheles philippinensis, were thought by Lee and Woodhill to have been A. meraukensis.14
ESTABLISHING A CONTROL ORGANIZATION
February 1943 was an important date in the malaria control picture in the Southwest Pacific, for it was at this time that the first malariologists and the first malaria survey units arrived. By June, malaria control units were at work in the theater, and thereafter malaria came and remained under firm control.
10 King, W. V., and Hoogstraal, H.: Three New Anopheline Records From New Guinea. J. Nat. Mal. Soc. 5: 153. 1946.
11 Belkin, J. N., and Schlosser, R. J.: A New Species of Anopheles From the Solomon Islands. J. Wash. Acad. Sc. 34: 269, 1944.
12 Belkin, J. N., Knight, K. L., and Rozeboom, L. B.: Anopheline Mosquitoes of the Solomon Islands and New Hebrides. J. Parasitol. 31 : 241-265, 1945.
13 Belkin, J. N.: Anopheles nataliae, a New Species From Guadalcanal. J. Parasitol. 31: 315, 1943.
14 King, Willard V.: Anophelines of the Australasian Region. In Malariology, edited by Mark F. Boyd. Philadelphia: W. B. Saunders Co., 1949, vol. 1,p. 510.
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During 1942, the Office of The Surgeon General had been studying the problem of malaria control in those areas where U.S. troops had to operate. As a result of these studies, the Office of The Surgeon General proposed (1) the assignment of trainedmalariologists as assistants to the surgeons in malarious areas, (2) theformation of special units to determine and control the local factors inmalaria incidence, (3) the education of the troops in protective measures, and (4) the utilization of labor personnel for antimalarial work.15
The Surgeon General outlined more fully the proposed malaria control organization in a letter to the Commanding General, U.S. Army Forces, Southwest Pacific, dated 24 October 1942. He invited him to submit requests for the additional military and sanitary personnel without delay.
In reply to this letter from The Surgeon General, the theater, on 1 December 1942, requested 1 malariologist, 6 assistant malariologists, 3 survey units, and 12 malaria control units. 16 A cadre of malariologists and an advanced echelon of three malaria survey units, the 4th, 5th, and 6th, were sent by air to the Southwest Pacific in February 1943. Dr. Howard F. Smith of the U.S.Public Health Service, on duty in theater headquarters, was appointed theatermalariologist on 27 February 1943 by Staff Memorandum No.3.
Theater Directives
In compliance with instructions, 1st Indorsement, General Headquarters, SWPA, 5 February 1943, the following basic sanitary and preventive measures for the control ofmalaria, dengue, and intestinal diseases were established for the informationand guidance of all U.S. Army personnel in SWPA:
1. In malarious andpotentially malarious areas, the wearing of shirts with long sleeves andfull length trousers is necessary to reduce the probability of mosquito bites.Wearing shorts and short sleeved shirts and going without shirts between sunset and sunrise is not authorized.
Mosquito repellent and intact mosquito bars wilt be provided for all personnel.
Suppressive quinine or Atabrine (quinacrine hydrochloride) will be administered to personnel in hyperendemic malarious areas, in accordance with instructions from the unit surgeon. Supervision is essential to insure that the drug is swallowed.
2. Campsites will be located as far from mosquito-breeding places as the military situation will permit. Except in the combat area, mosquito breeding will be eliminated by oiling, draining, filling, removing empty cans, bottles, coconut shells, and other containers for a distance of 1,000 yards from sleeping quarters and recreation areas. Experience has proved that a small, well-instructed detail, assigned permanently in each unit on sanitary and malaria control work, will procure the best results.
3. When troopsreceiving suppressive malaria treatment are removed to a nonmalarious area,the base section commander of the new area will be notified immediately.The number of troops removed from suppressive treatment at any time mustbe commensurate with the hospital beds available.
15 Letter, Col. John A. Rogers, MC, for The Surgeon General to The Adjutant General, 21 Sept, 1942, subject: Malaria control.
16 Coded Message CM-IN-C113, CINCSWPA, to the Surgeon General's Office, 1 Dec. 1942.
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4. Medical Field Manual 8-40, "Field Sanitation," describes in detail the most practical methods for use in the field. Special attention to the inspection and handling of foods, the supply and treatment of water, fly control and the disposal of human excreta and garbage is necessary. Prevention of disease, essential for a low noneffective rate, can only be accomplished by the rigid enforcement of sanitary measures.
5. Commanding officers of all grades are responsible for sanitation and for the enforcement ofthe provisions of sanitary regulations within their organizations and theboundaries of areas occupied by them.
These instructions were reinforced later by a more detailed directive designed to provide a malaria control organization consonant with that recommended by the Office of The Surgeon General (appendix B, p. 585).
Assignment of Duties
Under the organization, as established, a medical inspector special (malariologist) was on the staff of the Chief Surgeon, USAFFE (U.S. Army Forces, Far East). Under the Chief Surgeon, he was authorized to direct and coordinate the operations for malaria control. He also acted as a special adviser to the Chief Surgeon on allmatters pertaining to malaria and mosquitoborne diseases, including theavoidance of the introduction of the anopheline mosquito or of malaria intoareas then free.
The assistant medical inspectors special (malariologists) were assigned to Headquarters, USAFFE, and attached to the staff of commanders when necessary. These assistants were to advise commanders in the development of malaria discipline in all troops, to instruct personnel in malaria control measures, to assist in planning and supervising survey and control measures, to investigate malaria rates and malaria hazards of proposed campsites, and to furnish commanders with all pertinent information obtained.
Malaria survey units and malaria control units were assigned to USASOS (U.S. Army, Servicesof Supply) for administration but were under the control of USAFFE forthe performance of all duties pertaining to malaria control. These unitswere normally assigned to areas but under special conditions might be attachedto organizations of the Sixth U.S. Army, Fifth Air Force, or USASOS. Regardlessof attachment or assignment to duty, these units were under the technicaldirection of the chief malariologist. They functioned as follows:
The malaria survey units:
1. Determined incidence, distribution, and biology of mosquito adults and larvae in relation tomalaria.
2. Surveyed, mapped, and recommended to commanders measures for malaria control in specificareas.
3. Maintained a check on effectiveness of control measures by routine collection of adults and larvae.
4. Performed malaria parasite surveys among civilians and troops to determine incidence andspecies of parasites.
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5. Performed any special studies in regard to malaria or mosquitoborne disease required by the Chief Surgeon.
6. Kept commanders informed on all matters relating to malaria control in their areas.
The malaria control units:
1. Prepared detailed plans for malaria control measures.
2. Demonstrated and advised unit antimalaria details on approved methods of control.
3. Advised thecommander on the use of labor, civilian and native, in malaria controlwork.
4. Initiated plans and advised commanders regarding the maintenance of control measures inareas between units, docks, airfields, and similar areas used by troopsof all units.
5. Kept commanders informed on all matters relating to malaria control in their areas.
Personnel and units engaged in malaria control were furnished shelter and meals by organizations to which they were attached, or by organization commanders in whose areas they were assigned to duty. Movements of units within a base were effected by the base commanding officer upon request of the senior malariologist on duty therein. Movements of units from one base to another were directed by USAFFE.
Direct communication on technical matters between malariologists, survey and control units, and the Chief Surgeon, USAFFE, was authorized.17
Immediate Results
By late summer of 1943, the program for malaria control in this theater had been operating for approximately 6 months and was beginning to exert its full effect. In that time, the malaria rate in the U.S. Forces in New Guinea had been brought down from 970 per 1,000 men per annum in February 1943, to 200 per 1,000 per annum in August 1943.18
IMPORTANT FACTORS IN DEVELOPING THE CONTROL PROGRAM
Australian Medical Military Mission
During 1942, the procurement of adequate antimalaria supplies was very difficult. It was possible to get sufficient quinine, Atabrine, and Plasmochin naphthoate (pamaquine naphthoate) for treatment, but such antimalaria supplies as nets, repellents, insecticides, and sprayers were very inadequate. In fact, the supply situation was so unsatisfactory, from both the United States
17 Letter, Brig. Gen. L. S. Ostrander, Adjutant General, USAFFE, to Commanding General, USASOS, 12 June 1943. subject: Organization for Malaria Control.
18 Monthly Progress Report, Army Service Forces. War Department, 31 Oct. 1943, Section 7: Health, p. 13.
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and the United Kingdom, that an Australian Medical Military Mission was sent in September 1942 to the United States and the United Kingdom. The objectives of this mission were (1) to bring home to the United States and United Kingdom authorities the grave danger from malaria and other tropical diseases, and (2) to procure an adequate flowof supplies of Atabrine, other malaria drugs, mosquito netting, and repellents.The mission was successful in obtaining approval of a 6-tablet weekly regimenfor Atabrine and in obtaining promises for other needed supplies.
Inter-Allied Committee
Among the important factors in the program was the formation of an inter-Allied committee which advised the Commander in Chief of all aspects of the malaria problem. One of the reasons for the lamentable record in malaria control in 1942 and early 1943 was the absence of medical authority at the level of the theater commander's headquarters. The Inter-Allied Committee, under the chairmanship of Brigadier N. Hamilton Fairley, an international authority on malaria, wasset up to remedy this deficiency. It was this Committees recommendations, in the form of proposed directives which were approved and issued by General Headquarters to all commands, that were responsible for a uniform program of malaria control. USAFFE received its regulations from General Headquarters and reissued them to the American elements of the Allied Forces.
Assignment of Responsibility
The program and themanagement of the available resources for combating malaria were the responsibilityof one person, the Chief Surgeon, USAFFE. This made possible the following:
1. The formation of an organization for the control of malaria which carried on the attack on the breeding places of the anophelines in troop areas, assisted and advised the units in such areas in their control work within the unit area, aided in the distribution of available antimalaria supplies, and provided forschools, lectures, films, posters, and other educational devices for theinstruction of officers and men in the technique of malaria control.
2. The publication of regulations applying equally to all American Forces governing the use of individual antimalaria measures such as protective clothing, proper use of mosquito nets, repellent, the enforcement of suppressive treatment, and authorized methods of curative treatment.
3. The formulation of systematic programs for the rehabilitation of malarious divisions returning to Australia and the setting up of uniform standards for evacuation of malarious patients to hospitals to Australia from the Advance Base, and from Australia to the United States
4. The establishment of a card report system which furnished prompt and current information on the malaria rate in different areas and in different
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units, so that the malariologist knew where to center his chief efforts and also whether he was or was not being successful.
5. The institution of active research in prevention and treatment by personnel adequately trained and equipped and the restriction of indiscriminate experimentation.
The assignment of the malaria control organization to USAFFE resulted in some difficulties. Malariologists, for instance, could not travel to visit units in the field without securing permission for each separate move from both Sixth U.S. Army and Fifth Air Force, except on a personal basis, in which case no criticism or written report was permissible. All assistant malariologists were assigned to the 8th Medical Laboratory. Separate control organizations, however,for the Sixth U.S. Army, the Fifth Air Force, and USASOS would have beencomplicated and inefficient. Nevertheless, the system as organized workedwell, despite these difficulties.
Survey and Control Units in the Field
Malaria survey units accompanied task forces into new areas and performed the initial mosquito-breeding survey of areas as soon as possible after occupation. It was their function to locate and map all actual and potential breeding places in their initial surveys and to maintain weekly checks on the efficiency of control measures in the area. The survey unit also dealt with the collection and examination of blood smears for the study of malaria parasites in native populations as required, in addition to periodic selected surveys of well troops.
The malaria control units were used in all of the forward areas and normally accompanied the combat troops. With the aid of native labor, the control units were charged with the supervision of all environmental controls throughout any specific area. Major control projects were performed by the control units, with the assistance of Corps of Engineer units or, at times, Seabees (naval construction battalions).
In addition to the special purpose malaria control personnel, each unit commander was required to form an antimalaria detail of one noncommissioned officer and two enlisted men for each company, squadron, or smaller unit. These company detailsperformed routine antimalaria work in each unit area, and in their workthey were assisted, advised, and checked by the malaria survey and controlunits. Projects of any magnitude within unit boundaries were carried outas a special assignment of the malaria control unit.
MALARIA CONTROL ACTIVITIES
After official recognition of the basic problem that malaria was posing in SWPA, malaria control activities were initiated promptly. The methods of control were of two kinds--group and individual. Under the group method were two means of control, that of (1) permanent malaria control measures and (2) temporary malaria control. As a general statement, it could be said
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that, because of combat conditions andthe speed of movement in SWPA, permanent types of malaria methods were notwidely applicable. Therefore, under group measures, the temporary methods of control were the general rule; in actual combat conditions, individual methods of control were often the only methods available to the soldier to protect himself against malaria.
Besides these general activities, the malaria control organization also engaged in some special public health work, such as scrub typhus control, general sanitation, and some of the work usually done by the medical inspectors office in military camps and posts in the Zone of Interior.
The program for theperformance of group control methods was based on two special organizational units, the malaria survey and the malaria control units. While these units were administrative entities, they had close functional relationships--one survey unit usually serving to define problems and to check on the efficiency of two or three control units.
In general, the commandingofficer of a survey unit was a parasitologist or entomologist; of a controlunit, a sanitary engineer. The enlisted personnel were composed chiefly ofnoncommissioned officers to a total of 11 men, many of whom had special trainingqualifications.
These units arrived in a new situation at various times after D-day usually not before D + 15. The survey units proceeded to define the local problem through blood surveys of native population and mosquito and topographic surveys. The information collected was mapped, tracings from topographic maps being largely usedfor this purpose. This information was then given to the control units.Subsequent activity of the survey units was toward the more precise collectionof information on mosquito fauna and its ecology, resurveys of native populations,and checks on the efficiency of control units.
The malaria control units were equipped with appropriate light equipment for oiling and minor drainage. Its enlisted personnel performed some control operations but more often acted as supervisors of native labor or work details from service or combat units. The actual performance of control programs for a halfmile around a given organization was done by the personnel from that organization; other areas were handled by the control units.
The control program of a given area consisted, in general, of the following activities:
1. Treatment of breeding places with larvicides.
2. Eradicationof breeding places by drainage and filling.
3. Removal of native population groups to locations more than a mile from army units.
4. Strengthening of malaria discipline.
MALARIA CONTROL MEASURES
Throughout SWPA, malaria control was achieved through the use of many different measures, but chief emphasis was on the elimination or control of vector breeding places and the use of suppressive Atabrine therapy.
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Personal Protective Measures
An important measure of malaria control was the maintenance of personal protective measures. By means of directives, lectures, and periodic inspections, all officers exercisingcommand, as well as enlisted men, were indoctrinated along these lines. Itwas impressed on all unit commanders that this was the sole means of malariacontrol during combat and in new areas, until adequate environmental controlcould be established.
Nets and clothing. - Few, if any, head nets were worn or were available in the theater, for they were unnecessary and sometimes dangerous because they impaired vision. Bed nets were generally available but were not always used. In severalinstances, bed nets were not available for days or even weeks after establishmentof a beachhead. In most commands, the use of bed nets was strictly orderedand enforced except where combat situations made this impractical. In thebest disciplined units, nets were frequently inspected for defects and properusage. The jungle hammocks were dangerous in advanced positions because theoccupants were more susceptible to sneak enemy attacks. These hammocks weregenerally abandoned after a short trial.
The wearing of protective clothing, which included long trousers and shirt with sleeves rolled down, was required at all times, except when under mosquito nets, when bathing, or when engaged in athletics. Considerable difference of opinion was expressed in the field as to the best discipline in this regard. Some felt that shirts should be worn at all times, except when under a bed net or at bath. Itwas generally conceded by those responsible for malaria control that shirtsshould be worn constantly. Details laboring in the open sun, in holds ofships, on docks, or in screened buildings were allowed to remove shirts from0630 to 1730 hours.
Bathing was restricted to daylight hours except when screened showers were available.
Screening. - Screening, mostly galvanized 16 and 18 mesh, was installed on many of the barracks, hospital wards, messhalls, and recreation rooms, but almost solely at the older and more permanent bases. From a practical standpoint, absolute mosquitoproofing did not seem to be possible because of the nature of the buildings.
Repellents. - In better disciplined bases, mosquito repellent rules were well enforced in connection with attendance at outdoor movies at night. But a relatively small percentage of the total supply of such repellents as dimethyl phthalate was used for the intended purpose. Ample stocks of repellents were generally available, but mosquitoes were so few, except in unusual situations, that the men would not apply the repellents. However, experience indicated that men engaged in a new landing should be amply supplied with repellent for use after landing.
Rather crude tests of dimethyl phthalate indicated that it was not nearly so effective against Anopheles punctulatus in SWPA as against Anopheles
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quadrimaculatus in the United States; also, that Rutgers 612 gave more lasting protection than the dimethyl phthalate. The protection given by Rutgers 612, however, probably did not exceed 2 or 3 hours.
Aerosols. - Aerosol bombs were generally available in New Guinea but were often improperly used, as against flies, ants, and miscellaneous insects. A few were used to spray tents and bed nets. The tents were practically all without walls, and there was doubt of the efficacy of the Aerosol in these tents, even against mosquitoes.
It was reported thatbombs were used for cooling beer or for the construction of improvised smallrefrigerators.
Aerosol bombs were conscientiously employed in transpacific Air Transport Command planes.The Aerosol was applied freely after each takeoff, and before each landing.Aerosols were not observed in use in Australia or in Army planes in Australiaor New Guinea. Aerosol treatment of planes in Australia and parts of NewGuinea was probably unnecessary but was employed as the front progressedfurther north. There was some danger of introducing A. punctulatus into northern Australia, but this was not great. There was also the dangerof introducing that species into the Philippines or of introducing Anophelesflavirostris or other dangerous species into New Guinea.
DDT. - The application of residual DDT sprays to tents and bed nets and the impregnation of these articles with DDT were given consideration. Reports showed that adults of A. punctulatus usually rest on tents or other nearby articles for at least a few minutes either before or after feeding. Some impregnated nets did not prevent mosquitoes from biting through them, but caused the death of the mosquitoes as a result of the contact.
Antilarva Measures
Larviciding
For larvicidal purposes, DDT was supplied as commercially pure DDT, and as a 10-percent mixturewith talc, known as larvicide DDT, dissolving, and larvicide DDT powder,dusting, respectively. In these forms, DDT was prepared for applicationas a larvicide, either as an oil solution or as a dust.
A 5-percent oil solutionof DDT was an effective larvicide, with certain qualities which made it extremelyvaluable for use in malaria control. One of these qualities was that a smalldose of the solution would effectively treat a large area of water surface.Only enough oil had to be applied to secure coverage. Numerous laboratoryand small-scale field trials demonstrated that, where oils spread rapidly,1 cc. of the 5-percent oil solution will effectively treat 40 square feetof water surface. At this rate, 1 quart of 5-percent DDT oil mixture willtreat approximately 1 acre of water surface, as compared with 10 to 14 gallonswhen ordinary oil is used. A moderate amount of vegetation interferes verylittle with the spreading ability of the DDT oil solution. The use of DDToil solution simplified methods of application and, consequently, saved laborand equipment.
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Rate of application .- For temporary control, oil solutions of DDT were applied at 0.1 to 0.25 pound of DDT per acre. This amount is contained in the 1 and the 2½ quarts of the 5-percent oil solution, respectively. This rate of application destroyed existing larvae and pupae but did not have residual action. Eggs deposited within a day or two following treatment could be expected to develop into larvae and adults in the normal fashion. The treatment, therefore, was repeated every 6 to 9 days.
The amount of oil solution actually used in treatment was governed to some extent by thetype of equipment available and by the character of the area. The distributing apparatus sometimes was such that a much larger quantity of the oil solution was used than the calculated dosage indicated. When vegetation was extremely dense or a scum was present, distribution for adequate coverage often resulted in a larger dose of DDT than necessary for killing the current crop of larvae.
For residual action, single heavy doses of DDT oil solution were applied and curtailed breeding for periods ranging from 3 to 6 weeks in some situations, such as stabilized breeding places containing heavy vegetation which prevented shifting of surface films by wind action or rain. The most effective dose for this kind of treatment was about 5 gallons of 5-percent DDT oil solution per acre. Thisis equivalent to 2 pounds of DDT. Dosages in excess of this in most casesseemed to show no additive effects.
Methods of application . - Almost any type of container or apparatus available in the fieldwas used to dispense the DDT oil solution. Knapsack or other types of oilsprayers, with the spray nozzle adjusted to produce a fine spray, weregenerally satisfactory (fig. 57). Owing to the unusual spreading qualitiesof DDT oil solution, simple pouring from a bottle, bucket, or can was bothfeasible and effective on some breeding places; or the solution was pouredover wet gravel, sand, or earth, which was scattered over the water surface.Successful control of anopheline breeding for periods of 2 to 3 weeks wasobtained in ponds on which bags of sawdust soaked with equal parts of 5 percentDDT in crankcase oil and 10 percent DDT in gasoline were placed. A weightwas added to the bag to make it submerge. To keep the bag from sinkinginto the mud at the bottom of the pond, a stoppered empty bottle or someother buoyant object was attached. The DDT oil solution gradually releasedfrom the soaked sawdust was observed to control breeding in roadside pondsfor 2 to 3 weeks. In the treatment of flowing streams, the oil solutionwas applied at rather wide intervals, since the moving water assisted inspreading the larvicide. In treating streams, standard mechanical methodsof the dripcan type were sometimes used.
For temporary control, DDT dust mixture was applied in the same manner as paris green dust. DDT dust was effective when applied at the rate of 0.1 pound of DDT per acre. This means 10 pounds of a 1-percent dust, or 2 pounds of a 5-percent dust per acre. To insure adequate coverage of breeding
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FIGURE 57.- Refilling knapsack sprayers with oil, 8th Malaria Control Unit, New Guinea.
areas, the 1-percent dust was preferred where transportation of materials was not too difficult.
For residual control, a single application of the 10-percent DDT dust concentrate at the rate of 10 pounds per acre was sometimes used to secure a residual killing action for 3 to 5 weeks. Residual action was more likely in water areas covered with thick vegetation where the dust film was protected from wind and wave action. 19
Oiling with fuel oil in hand spray pumps (knapsacks and especially with CWS (Chemical Warfare Service) decontamination sprayers and some sleeve-type firefighting units) was the most general procedure. Some use was made of buckets and mops, sprinkler pails, and oil-impregnated sawdust, owing to lack of sprayers. Where native labor was available, it was usually employed, and some of it was quite satisfactory. This was more often true in Australian New Guinea than in Netherlands New Guinea. For the use of these laborers, the governments of Australia andNetherlands East Indies were reimbursed at a low rate by the United States(fig. 58).
Sprayers.- Knapsack sprayers were often scarce and the type furnished were short lived. The following suggestion for improvement of this equipment was offered by Capt. John Coffee of one of the control units on Noemfoor: The
19 War Department Technical Bulletin (TB MED) 14, 3 Mar 1944.
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outlet should be reinforced, the bottom securely soldered in, the sponge rubber seal around the top improved, and the top clamp for holding the hose made stronger. Rubber diaphragms ofthree thicknesses of auto inner tubes were installed in the field, butthese, too, were short lived. A spray outfit used by one malaria controlunit consisted of two tight drums to serve as pressure tank and oil containerscoupled to a small compressor and carried in a light tank.
There was need for good substantial hand sprayers for use in the mess and barracks, as they were not available in advanced areas. The small atomizers (two sizes), developed at the Orlando Laboratory in Florida for hand application of spray concentrates, failed to have any special advantages. They could not be carried into combat by troops and were not as useful in stabilized areas, as were the Aerosol bombs and hand sprayers.
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A number of power spray units were improvised in the field and were especially helpful when labor was scarce.
Airplane spraying . - Airplane application of DDT in oil was undertaken on a limited scale. Tests were made in Australia and also in New Guinea. Experimental tests of this method of controlling mosquitoes were carried out in July 1944 at Nadzab with CWS tanks on an A-20 plane and, later, with a special tank (195 gallons) with manual control on a B-25. As a result of this work, it was concludedthat DDT was 100 percent effective against flies and 90 percent effectiveagainst adult mosquitoes, but was not effective against the mites transmittingscrub typhus.20
The second test ofthe efficiency of airplane distribution of DDT was made on Owi Island, on20 July 1944. This was primarily to test the value of the spray against mites,but observations were also made of the effects on flies and mosquitoes. Thespraying did not appear effective against mites, but flies were not noted after spraying; however, the area of effective coverage appeared to belimited. Biak was sprayed 2 days later, and Sansapor on 4 August, 4 daysafter the landing was made on that island.
Morotai was sprayed on D-day, 15 September, the first instance where this was done; further sprayings were made on D + 1 and D + 14. The results were reported by Capt. P. J. Darlington, Jr., SnC, as follows:21
I arrived on shore at 0950 on D-Day, and at 1130 the DDT planes came over. They came over again on D+1 between 1100 and 1115. The weather was clear and dry with only aslight breeze. The planes I saw flew about 100 feet above the ground and followed parallel paths 200 yards or less apart * * * It seemed to me the planes laid down too little spray. The visible mist trails which they left in the air were very thin and only a few yards wide.
There were very fewadult insects here to begin with so far as I could find in the few hours before the first spraying had time to take effect. I saw only one adultmosquito and a very few miscellaneous flies. There are still only a fewadult mosquitoes and flies here, except in a few places, but it is a questionhow much of the credit should go to the DDT. I was not able to find breedingplaces in time to make a survey of mosquito larvae before the spraying, buton the morning of D+4, 3 days after the second spraying, in an area overwhich I saw planes pass on both D-day and D±4, in a shallow open swamp,I made about 100 dips and got nearly 1,000 Anopheles and many culicine larvae. The Anopheles were of all instars, including many fourth, but I found nopupae. The absence of Anopheles pupae three days after the second sprayingmay mean that the DDT killed the large larvae of this species, but certainlythe effect on larvae was not great, even in this completely open water, andthere was no residual effect.
A single heavy application on D-day would probably be better than two light ones on successive days. In any case, the amount of DDT put down on Morotai was probably insufficient. Although initial spraying of a new beachhead has to be done by the Air Force from a distant base, later sprayings ought to be done from the beachhead itself by properly equipped Cub Planes.
20 Memorandum, Col. Maurice C. Pincoffs, MC, to Lt. Col. Gottlieb L. 0rth MC, 11 Aug. 1944, subject: Insect Control (DDT), SWPA.
21 Letter, Capt. P. J. Darlington, Jr., SnC, Office of the Surgeon, XI Corps, to Surgeon, Sixth U.S. Army, 27 Sept. 1944, Subject: Airplane Spraying of DDT on Morotai Island.
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The 15 September spraying was at the rate of 0.13 pound per acre, the spraying next day was at the rate of 0.46 pound per acre, and on 29 September the rate was 0.30 pound per acre.
Biak was sprayed in October 1944, and Hollandia in November.
The plan of applying DDT in connection with landing operations appears to have been well thought of by both malaria control men and operational officers. The latter did not appear to have been sufficiently impressed, however, with the need for previous preparations of supplies, equipment, flying personnel, and careful application.
Oil solutions of DDT were used, but Mr. Douglas Waterhouse (Council for Industrial and Scientific Research at Canberra) thought emulsion might be applicable. The following formula was his choice after testing many emulsifying agents: From 20 to 25 parts detergent (Bozetol, Tween 60, or Solvadine BL) used with 75 to80 parts of chlorobenzene, containing 60 percent DDT. The mixture is suitable for preparing emulsions with any type of water and is quite stable in storage.
Extensive work was carried on during November 1944 under the direction of Capt. William C.McDuffie, SnC, to develop standard techniques for applying DDT oil solutionsfrom the air. As a result of this work, improvements were developed whichresulted in more effective use. As the combat area moved north, however,the need for airplane application of DDT lessened.
Equipment for airplane application of DDT received attention from the Australian and Americanauthorities. Little testing of the Husmann spray equipment on Cub planeswas done. Some tests carried out by the Fifth Air Force in March 1944 showedthe equipment to be satisfactory for small-scale work. Most authoritiesfelt that such equipment might be advantageously employed in base or intermediateareas where extensive breeding places must be treated and especially wherenative labor was scarce. Major emphasis was placed and, in the opinion ofthese authors, rightfully, on the development of equipment for use on fastplanes in combat areas.
The Australian group experimented with the use of wing and belly gas tanks on Beaufort lightbombers, which planes were widely available for such use. The wingtanksheld about 90 gallons (British) and belly tanks about 135 gallons. They"were already fitted with dump valves, about 5 inches in diameter, controlledby air pressure lines from the cockpit. They could be opened and closedreadily, thus conserving the solution. The exhausts were fitted for applyinginsecticide with a tapered spout similar to the spout on the American CWStanks, and the oil was broken up well with the slipstream. Initial workin New Guinea indicated that airplane spraying with DDT was highly effectiveagainst larvae and adults of Anopheles punctulatus.
In preliminary tests with a 5- to 8-mile wind, flying at a height of 100 feet at a speed of170 m.p.h. and the two wing vents open, good coverage was secured overa swath about 300 feet wide and some coverage, for 800 to 900 yards. Itwas observed that, in some instances, as little as 20 percent of the solutioncould
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be accounted for on the ground as indicated by dyes in the solution. The two openings in the belly tank (about 14 inches apart) appeared to give coverage of a somewhat narrower swath. The effects of corrosion of tanks and equipment, and its effects if tanks were subsequently used for gasoline, had to be considered.
In the U.S. Army group, initial work was done with a Piper Cub plane and the Husmann spray unit. Later tests with CWS tanks (M-10) on A-21's with a metal disk in front of the glass disk were made on Owi. The metal disk was provided with a wedge-shaped opening with the curved edge down. Then, the glass was broken by detonation, the disk slowed down the discharge, and permitted complete discharge ofthe oil. This work indicated the need of manual control. An A-21 with oneof these tanks, flying 220 miles per hour at 50 feet, gave effective coverageof an area approximately 2 miles long and 100 yards wide. In these tests,32 gallons of material was used, and it covered about 72 acres.
A new CWS smoke tank(ELB) of 195-gallon capacity was mounted in the bomb bay of a low-level bomberaircraft B-25-D. This equipment, flown at 200 m.p.h. at an altitude of 100feet, gave effective covering of an area 200 yards wide and 4.4 miles long.The preliminary work was done at Nadzab, and excellent kills of test insectswere secured.
Drainage andfilling
With the rapid northward shifting of the war theater, extensive and expensive drainage operations exclusively for mosquito control were not warranted and were not carriedout. Furthermore, the rather heavy machinery necessary to carry out thisprocedure economically was not generally available, since it was requiredfor construction of airstrips and roads. There were some rather large hand-dugditches near Lae, and such work was expedited by the use of a bulldozer toclear off the surface. Some dynamite was also employed for swamp ditching.Shell craters were used for earth-covered dumps and thus were gradually filled.Roadside drainage was improved in many cases, thereby eliminating importantbreeding places (figs. 59 and 60).
Destruction or burial of manmade water containers was a first requisite after taking over previously inhabited areas. Experience showed that sage swamps and rain forests should be opened up as little as possible, since elimination of shade inducesbreeding. Logging operations, however, did that and also left the areascut up so that water remained on the ground. These areas required specialattention and were difficult or impossible to control by conventional larvicidemethods.
Naturalisticcontrol
Little or no effort was made to transplant fish into mosquito-breeding pools. So many of these pools were temporary that the fish would soon have been killed. In some more permanent water where breeding occurred, top-feeding
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FIGURE 59.- Digging drainage ditch, 8th Malaria Control Unit, New Guinea.
minnows were observed in great numbers and undoubtedly served to hold down mosquito breeding. Manipulation of fish did not appear to have much practical value under New Guinea conditions. Some predaceous mosquito larvae were collected and reared.
Water impoundment and control of water levels seemed to have no place in the control of mosquitoes in connection with the war operations in New Guinea.
Mapping
Some survey units reported shortage of drawing equipment for mapping. Opinions regarding the value of maps differed. In general, they were thought to be useful even though the picture regarding breeding places created by U.S.
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FIGURE 60.- Completed drainage ditch, 8th Malaria Control Unit, New Guinea.
operations changed almost from day today. Aerial photographs were used by some but were not generally regarded as highly useful.
Adult Mosquito Control
Environmental measures that were employed in this theater against adult mosquitoes included killing by means of insecticide sprays and screening. Under ideal climatic conditions, the pyrethrum spray, as dispensed by the Freon Aerosol container, was very effective. However, in the majority of tropical conditions where an attempt was made to maintain the maximum ventilation, it was found that the efficiency of the pyrethrum spray was much less than would be expected in a relatively confined area, owing to the rapid dispersion of the mist by the breeze.Airplanes, when returning from malarious to nonmalarious areas, were sprayed,in an attempt; to prevent further spread of mosquitoes, and introductionof species.
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No use was made oforganized adult spraying details, because the principal malaria vector (A. punctulatus), when on the wing or attempting to feed, is often not noted by the lay person and in many areas was difficult to capture by experienced observers using standard catching methods. On other occasions, adult spraying was impossible because of inadequate supplies of pyrethrum sprays, although this situation was later corrected. Wire screening, even when available,did not prove practicable in the forward installations of this theater. Thiswas because the majority of the buildings were of native type (thatched)of construction which did not lend itself to screening. Even buildings ofbetter construction were left with many openings through which adult mosquitoesgained admission. Some observers believed that, unless extremely intelligentuse of screening was made, the employment of it led to a sense of false securityrather than to effective protection.
Theater directives specifically stated that all staging areas and campsites were to be located so as to avoid proximity to native villages and camps and to those areas known to have a heavy population of malaria-carrying mosquitoes. Natives were removed for at least 1 mile from all installations between dusk and dawn.
Suppressive Treatment
Troops under orders to move from the Australian mainland to malarious areas were given two Atabrine tablets (0.2 gm.) daily for the 7 days immediately preceding the expected date of arrival in malarious areas. Troops arriving in malarious areas without having received previous suppressive medication, as frequently happenedwith new units from the United States, were given four Atabrine tablets(0.40gm.) daily for the 3 days immediately after arrival, and then continuedon with the routine suppressive treatment. Standard Atabrine treatment wasdirected for all troops in malarious areas; the policy was one tablet (0.1gm.) per man daily. Suppressive Atabrine administered by roster in the presenceof a commissioned officer in such a manner as to insure that each personactually swallowed the medication. Under certain circumstances, such asin combat areas, where it was found impossible to hold a daily Atabrine formationand the need for maintaining a fully effective trained unit over a periodof time was particularly great, an alternative regimen of fivetablets (0.5 gm.) twice weekly was used with success and was sufficient to maintain effective blood Atabrine level.
Method of administering Atabrine
The method of administering Atabrine after mess, preferably after the evening meal was as follows:
1. The soldier proceeded to lyster bag, or other water supply. Water was allowed to run into hiscanteen cup to the depth of not more than one-half inch, by a private detailedto this duty and to that of regulating the rate at
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which the column of men approach the "Atabrine table." This was important. Crowding in the line permitted the improper disposal of the drug.
2. With canteen cup containing water in his left hand, the soldier proceeded to receive hisAtabrine with at least a distance of 3 feet between him and the soldier preceding and the one following.
3. The approximate dose of Atabrine was delivered into his outstretched right hand by an enlisted man detailed to this duty. Under no condition was the soldier allowed to "help himself" to the Atabrine. Without closing his hand, the soldier, facing the supervising officer, tossed the Atabrine into his mouth, drank the entire contents of the canteen cup, and inverted the empty cup squarely upon the table. These acts were constantly supervised by the commissioned officer from the beginning to the end of the "muster."
4. The soldierproceeded to a distance of at least 3 feet to "the checker" (noncommissionedofficer) to whom he stated his full name and rank and waited until hisname was checked on the roster.
5. The soldierthen assumed the position of "at ease" in a second formation, new additionsto which took their places in front ranks.
The formation was continually supervised by a noncommissioned officer whose duties were to detect any attempt at improper disposal of the Atabrine, to keep the formation at ease, and to release small formations after the last man to arrive in the respective formations had been present at least 5 minutes. Stragglers appeared before an officer to take their Atabrine and to be credited for having done so.
The adoption of thesimple method of Atabrine administration caused a complete cessation of recurrentattacks of malaria in large bodies of men, all of whom were subjected toacute episodes of this disease.22 The success rewarding Atabrinesuppressive therapy was dependent upon the thoroughness with which the administrationof the suppressive agent was supervised.
Suppressive treatment in combat
"The Suppression of Malaria in Combat" is the title of a report forwarded to The Surgeon General from a malaria research unit in the Southwest Pacific and is summarized as follows:23
There is no longer any doubt that Atabrine is highly effective in the suppression of malaria even in combat, but there has been no unity of opinion as to just how much malaria might be expected under suppression. It has been maintained by some that there need be no malaria if everyone took the required amounts of Atabrine. This belief was based on experiments on large but necessarily limited numbers of men under relatively favorable conditions. The few who reported withclinical malaria had been unable to take the drug.
22 Letter, Lt. Col. George G. Duncan, MC, Surgeon, 5215th Reconditioning Center (Prov.), to The Surgeon General, 4 Jan. 1944, subject: Medical Department Report, inclosure thereto, pt. III, The Atabrine Muster.
23 Malaria Report No. 300, The Suppression of Malaria in Combat, 6 Oct. 1944, in Board for the Coordination of Malarial Studies, A Joint Body Composed of Representatives of the Office of Scientific Research and Development, the Army, the Navy, the U.S. Public Health Service, and the National Research Council, Vol. III. [Official record.]
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Serious toxic effects--atypical lichen planus, aplastic anemia, and acute psychoses--were infrequent, though an increasing incidence was noted during 1944. Sometimes, they resultedin prolonged disability, evacuation from the theater, and rarely, death.Moreover, knowledge of toxicity had a bad effect on morale. So did the relativelyharmless but sometimes alarming yellow-green pigmentation which occurredin the majority of those long under Atabrine suppression. There was alsoan unfounded but highly prevalent rumor that Atabrine suppression led toimpotency and sterility. Such a bad effect did these toxic effects and theserumors have on morale that they sometimes constituted a serious interferencewith effective Atabrine suppression. All mention of malarial incidence andtoxic effects of Atabrine had to be banned by the censorship to avoid quotationsin the Australian papers which reached the Allied Forces.
Supplies of Atabrine generally were adequate throughout the theater. In the few instances when the supply ran low, there was always enough available among the men to avoid a break in the routine.
Conclusions of a controlled study of the personnel of the 126th Infantry Regiment, 32d Division, as follows:
1. When 1.0 gm. Atabrinewas taken every week, at least 98 percent of the troops were protected againstclinical malaria.
2. Difficulties of administration in the field and the inability of a certain portion of the men to retain their 0.5 gm. were at least three times as important as true "breakthroughs" in producing a rate of 140 per 1,000 per year.
3. Even when more than 50 percent of the troops would have developed malaria in 2 months had they not been protected by Atabrine, suppression with this drug was capable of keeping the clinical rate during combat at a negligible rate.
Epidemiological aspects of suppression
A summarized field research report on the epidemiological aspects of Atabrine suppression follows. 24
As this was the firsttime that an Atabrinized army had fought in a hyperendemic malarious area,it was important that the part that Atabrine played not only in the suppressionof clinical malaria but in the prevention of epidemic malaria be understood.Atabrine had a direct effect on vivax gametocytes and prevented thedevelopment of falciparum gametocytes in adequately suppressed individuals.Thus, it prevented the infection of mosquitoes, which in turn meant fewerinfections of other soldiers. This cutting off of the source of further infectionmade it possible for troops to fight in hyperendemic areas with a high degreeof protection from Atabrine and a resultant greatly decreased amount of infection.
24 Letter, Malaria Research Unit, 3d Medical Laboratory, to The Surgeon General, 8 Jan. 1945 subject: Report No. 15, The Epidemiological Significance of Atabrine Suppression.
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Epidemic falciparum malaria in the tropics acquired its explosive nature by the geometric increase in the number of crescent carriers which developed in the nonimmune population. Although the increase of anophelines brought about by the troop operations also played a large part in the genesis of the epidemic, anincrease of anophelines alone with minimal number of gametocyte carrierswas incapable of producing the epidemics experienced by both the Americanand Australian Armies in the early campaigns.
Unfortunately, there are no studies available of the gametocyte and mosquito infection rate,from the beginning to the end of an epidemic, but it is possible to comparethe rates obtained during endemic and epidemic situations. The outstandingepidemic of malaria in an unprotected and nonimmune population occurredin the Netherlands East Indies colony of Tanahmerah; here, the attack ratereached an average of four yearly attacks per person. It was during thisepidemic that the highest infection rate of mosquitoes was obtained--12.7percent. Heydon 25 at Rabaul found a sporozoite rate of 3.9percent and an oocyst rate of 3.6 percent in 220 dissections, despite alow parasite rate in the natives. Heydon, however, believed that, sincemost of the infected anophelines were collected from houses with known gametocytecarriers and since they were kept for some days before dissection, thisrate does not reflect the general rate in nature.
Finally, it is of interest that the lowest reported infection rate of mosquitoes (0.06 percent of 1,735 dissections) was obtained during an off season for malaria transmission at the native villages near Lalapipi, and it was here also that the lowest gametocyte rate was obtained in the native surveys. It is true that local conditions contributed to this abnormally low rate in A. punctulatus, but it is believed that the data just cited established the fact that in New Guinea and elsewhere there is a direct, although not constant, relationship between the epidemicity of a situation and the infection rate in the anopheline vector.
The combination of(1) an efficient vector in sufficient numbers, (2) a large number of susceptibles, and (3) a few infections to start the chain of transmission make epidemic malaria inescapable. This had been true regardless of the size of the original reservoir. One of the most devastating of military epidemics occurred during the southern campaigns in the Civil War in areas which had only moderate endemicity. Thus, the amount of infection in the natives is of relatively little importance in the outbreaks of epidemic malaria in unprotected troops. If, however, the great majority of soldiers cannot become gametocyte carriers because of adequate Atabrine suppression, the epidemic cannot occur. Theamount of infection left behind by enemy troops will have a short-lived effect,while the amount of infection caused by the natives is of much less importancesince contact is usually not close.
25 Heydon, G.A.M.: Malaria at Rabaul. M.J. Australia 2: 625-634,December 1923.
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If the foregoing thesis of the smothering effect of Atabrine suppression on epidemic malaria is correct, it should be possible to demonstrate a direct relationship between the malaria rate under suppression, the gametocyte rate in the troops, and the infection rate of the mosquitoes collected from troop areas (tables 75 and 76). Because Atabrine had a direct effect on the vivax gametocytes, but none on the falciparum crescents, one expected to find that with good but imperfect suppression only falciparum carriers are discoverable.
TABLE 75.-Comparison of gametocyte rate and malaria rate in selected troops, 1944
TABLE 76.-Mosquito dissections (Anopheles punctulatus)
The expected falciparum gametocyte rate in troops as shown in tables 75 and 76 may be calculated on the following assumptions:
Given a rate of 200per 1,000 per year, one of every five men was infected each year. If halfof these infections are falciparum and if one-third of these infectionsbecome crescent carriers, then 1 of every 30 men will he a crescent carriereach year. Since the carrier state lasts a little over a month, at any timeone might expect 1 in 300 men to have crescents.
If one assumes that the average life of A. punctulatus is about 2 weeks, and if at least 50 percent of her blood meals are human, then the average A. punctulatus will have had at least two human blood meals. If only 1 per 300 menare crescent carriers and if only one-half of the crescent carriers areinfectious for mosquitoes, then only 1 per 300 of the wild
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caught anophelines mar be expected tobe infected. These calculations are made for the falciparum infections alone. The presence of vivax carriers at the same time would change the figures but would not be great enough to change the order of magnitude.
It may be concluded, therefore, that the majority of infections which are acquired by troops under poor or inadequate suppression come from the troops themselves, and as suppression becomes more perfect, a larger percentage of the infections will come from the natives and enemy troops.
Nevertheless, although the troops themselves were the chief source of infection, it was also true that in many areas of the theater there were considerable reservoirs ofgametocytes in local populations. The removal of villages to an optimaldistance of 2 miles from troop areas and the barring of troop areas to allnatives from late afternoon until full morning light were certainly importantmeasures for lessening the transmission of malaria to troops.
Plasmochin naphthoate
Plasmochin naphthoate has often been used in the routine treatment of falciparum malaria with the idea of eliminating crescent carriers and thus of cutting down on the spread of the infection among the troops. This would be sound reasoning if most of the persons who are carriers of gametocytes had previously been hospitalized for malaria. With increasingly adequate suppression, however, the gametocyte rate drops. Secondly, only a small proportion of the gametocyte carriers found on routine surveys have been hospitalized for malaria. Of the four crescent carriers who were picked up on routine surveys and whose histories were checked, one denied ever having been sick. Of the others, one had been hospitalized for dengue and two for fever of undetermined origin several weeks previously. Parasites had not been detected in any of them. Thus, none of these cases would have received Plasmochin naphthoate through routine treatment of malaria. The development of a crescent carrier state during indifferent suppression was demonstrated in another person who on routine survey was found to have 100 rings per cubic centimeter of blood butwas without symptoms. A repeat smear a month later showed 10 crescents, althoughhe had at no time been sick.
Some specific studies
In the following section, specific data are presented concerning a variety of units under different conditions.
A great deal of emphasishas been placed on the difficulty of malaria control in combat areas withthe result that it is often not realized that even during "good mosquito control" in an established base, a large portion of the men became infected. A port company which arrived in one of the bases some months after it was established and which was quartered out of flight range of any native village became, under indifferent suppression, highly infected. Six months after arrival, they had 17.2 percent positive smears and had a rate of 442 per1,000 per annum. A station hospital which arrived in the base some
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months after that had 7.1 percent positive smears with a rate of 287 per 1,000 men per annum. Because of poor suppressive and little personal antimosquito protection, these troops served as thesource of their own infection and built up a high rate despite the extremepaucity of adult anophelines and the lack of contact with infected natives.
12th Cavalry Regiment . - The 12th Cavalry Regiment of the 1st Cavalry Division is an interestingexample of what good Atabrine suppression can do in the way of preventingepidemic malaria in troops. The malaria rates for this regiment from Marchto July 1944, which are representative of the division, are shown in thefollowing tabulation:
Month Rate per 1,000men per annum
March ...................................................................................................48
April.......................................................................................................90
May........................................................................................................48
June........................................................................................................48
July.........................................................................................................54
Previously during staging, they had only a few cases in the whole division. Surveys were conducted on the troops on 24 April and 13 July 1944, 1½ and 4½ months, respectively, after the invasion of the Admiralty Islands. On the firstsurvey, Atabrine levels were very satisfactory, and 2.2 percent of the 184men showed positive smears. On the second survey, the Atabrine levels haddropped so much that had this group of men been heavily infected one wouldhave expected a high malaria rate. Actually, they did not have a high rate,and only 3 percent of 200 men showed positive smears.
These results were aided by the fact that Los Negros is a predominantly coral island, andthus both adult and larval anophelines were not common. Only 30 adultswere taken on repeated collections near the native village. The paucityof anophelines on Los Negros, however, explains the overall low rate whichwas present in the entire division throughout their period of combat andfollowing, for anopheline larva and adults were very common on the muddyclay soil of Manus Island. One evenings all night catch in an Australia NewGuinea Administrative Unit labor camp about a week after combat troops hadleft the area yielded over 150 adults. The authors suggest then that thecampaign on the Admiralty Islands (map 32) is an excellent example of theability of Atabrine suppression therapy to prevent epidemic malaria andthus a large number of infections, even during combat in a hyperendemicmalarious area.
32d Infantry Division . - A different picture was presented by the 32d Infantry Division. Theirprevious campaigns had left them with a large load of infection to startwith, although by the end of 1943 and the beginning of 1944 about one-half of the men were replacements. During the early part of the Saidor Campaign, anopheline breeding was excessive and large numbers of adults could occasionally be collected. The largest catch made by the personnel of the 5th Malaria Survey Unit was 889 in one tent in an all night catch.
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During this period, the entire division, including the 128th Infantry Regiment which was studied in early May 1944, was taking 0.5 gm. Atabrine twice weekly. This regimen, however, did not produce protective plasma levels. It is natural then that with the swarms of anophelines and with the inadequate suppression which allowed crescent carriers to develop (two were discovered in 400 smears) considerable infection of the troops would take place. Yet suppression was good enough to prevent conditions approaching epidemicity as shown by the low infection rate in the anophelines (table 77).
TABLE 77.-Malaria attack rates in the 126th and 128th Infantry Regiments, January-July 1944
Special studies weremade on the 126th Infantry Regiment during July in the midst of their campaignat Aitape. In many ways, conditions at Aitape were very different from thoseencountered elsewhere in New Guinea. For weeks, the perimeter was relativelystatic. Large areas of the jungle were cleared for lines of fire in frontof the pillboxes. The continual creation of new breeding places through necessaryconstructional work in the muddy sunlit areas of the jungle out of reachof ordinary spraying made effective mosquito control very difficult. Collectionof adult anophelines at this time from the jungle hammocks scattered throughoutthe area yielded 122 anophelines. None of these was found to be infected.
At this time, special study was made of the 126th Infantry Regiment which during the previousmonth had had a high malaria rate. No crescent carriers were found in the173 men studied, although 10 percent of the replacements were positive oncareful search of thick smears. Atabrine determinations taken on the menat random showed excellent levels, as reflected in the drop in the malariarate during the month.
The story of this division may be reconstructed along the following lines: They renewed their campaign with inadequate suppression which allowed sufficient carriers to develop among the troops so that when they were fighting in areas of high anopheline density a large proportion of the men became infected.
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Nevertheless, suppression during both of their campaigns was great enough to smother any tendencies toward an epidemic, as shown by the low rates of infection in the mosquitoes. The story of this division again is an example of the interrelation ofmosquito control and Atabrine suppression. These two methods of militarymalaria control are complementary. If one method is inadequate, then a greatload is placed on the other.
41st Infantry Division. - It is often pointed out that, with Atabrine suppression exerting its dampening effect, it is impossible to know just how much transmission is going on in an area. It is suggested that greater attention be paid in the tropics to the ratio of falciparum infection to vivax malaria as a measure of this transmission. It is now well recognized that falciparum infections survive only a few weeks under Atabrine suppression, and thus cases of falciparum malaria which occur in suppressed troops must have been acquired recently. In other words, one is able to follow the rise and fall of the transmission by following the percentage of falciparum malaria in troops under suppression just as well as during an epidemic in unprotected individuals. The data in table 78 were reported from the41st Infantry Division during and after their campaign on Biak. This ruggedcoralline island had very few breeding places, and for this reason, transmissionapproached zero shortly after the Division landed at the end of May. Afterthis, the incidence of falciparum malaria waned.
TABLE 78.- Number of cases of malaria in the 41st Infantry Division, June-August1944
SIXTH U.S. ARMY TRAININGCENTER
The objective in establishing the Sixth U.S. Army Training Center was to receive from combat units personnel infected with malaria and to prepare them physically and mentally for further combat duty. The surgeon was instructed as follows:
In view of the disappointing results yielded in many cases by methods now in practice in both therapeutic and suppressive treatment of malaria, the Surgeon of the Center will, with the approval of proper authority, make a diligent search to discover and institute other and more promising means of dealing with this problem.
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In pursuing this objective, the personnel were divided into companies, and Atabrine was administered according to seven different programs. In all instances, the Atabrine was given after the evening meal, by roster, and supervised by commissionedofficers. Parallel studies were conducted in such a manner as to revealunfavorable as well as favorable results following the respective suppressivetreatments. The comparative studies comprised:
1. Average daily attendance at sick call from the respective companies. Conditions and symptoms noted at sick call.
2. Admissions to the hospital for all causes.
3. Admission to the hospital for proved recurrent attacks of malaria.
4. Incidence of tachycardia, splenomegaly, changed hemoglobin values, loss of weight, abdominal pain, diarrhea, vomiting, fever, arterial hypertension, albuminuria, blood smears positive for malaria organisms, and increased "Atabrine Tint" to skin and sclerae.
5. Need for reclassification to permit milder training.
6. Changes in body weight.
7. Blood plasma Atabrine levels.
These Sixth U.S. Army Training Center studies were summarized as follows:
1. Each of several Atabrine suppressive regimens was found to be effective in abruptly and completely interrupting recurring attacks of malaria.
2. Despite intensive military training for 4 weeks, in two of which the exercise periods exceeded 80 hours per week, it was not possible to precipitate an acute attack of malaria in any of the personnel protected by Atabrine.
3. Recurrent attacks reappeared from 2 to 4 weeks after discontinuing suppressive therapy.
4. There was no evidence that Atabrine afforded less protection after prolonged administration.
5. Extensive parallel clinical and laboratory studies conducted over a period of over 4 months failed to reveal any disadvantage in using a larger amount of Atabrine given twice weekly, over a small dose given 6 days per week.
6. Determination of the concentration of Atabrine in the blood plasma revealed that whenAtabrine was given in doses of 1.0 gm. per week (0.5 gm. on Mondays andFridays), or, when given in doses of 0.4 gm, every third day, levels exceeding30 gamma per liter (the therapeutically effective level) were reached atsome period in each 24 hours. It was also found that, for the most part,the plasma Atabrine values remained below 30 gamma per liter when 0.1 gm.of Atabrine was given daily for 6 days each week. Although these low concentrationsprevent recurrent attacks of malaria under favorable circumstances, theycannot be expected to afford the same degree of protection offered by higherconcentrations under unfavorable circumstances.
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7. Intensive military training failed to affect appreciably the concentration of Atabrine in the plasma concentration.
8. Frequent plasma Atabrine determinations made on personnel receiving the greatest amounts of Atabrine failed to reveal any significant changes in the values between the fifth and ninth weeks of the suppressive therapy. Upon withdrawal of thedrug, the plasma Atabrine concentrations declined rapidly, reaching levels affording little antimalaria protection on the fourth day.
It was further concluded that Atabrine in doses of 0.5 gm., given every Monday and Friday. offered a high degree of antimalaria protection and was practicable of application. Atabrine in doses of 0.4 gm. every third day was equally effective, butits administration was more complicated. The selection of the therapy of0.5 gm. of Atabrine on Mondays and Fridays, recommended for troops in combatwas based on:
1.. The extremely small incidence (less than 1 percent) of unfavorable reactions.
2. Highly protective plasma Atabrine levels.
3. The especially abrupt cessation of recurrent attacks when this suppressive therapy was instituted.
4. The practicability of administering the drug to troops at the front in contrast to the regimen requiring daily medication.
Only 5 persons out of over 4.000 presented a real problem by having a persistence of gastrointestinal disturbance after the ingestion of Atabrine. Three suffered from a psychoneurosis with a moderately severe anxiety state. Two had preexisting chronic disorders of the digestive tract, and because of their inability to retain the drug, each suffered a recurrent attack of malaria at the Center.
MALARIA RESEARCH GROUP
Mention should also be made of the results obtained by the malaria research group, including, for example, the various studies made by Dr. Frederick B. Bang and others on the relative effectiveness of different forms of therapy; the proof of the efficiency of Atabrine malaria control in a malarious area that was obtained as a result of the "Sooner" expedition to Milne Bay; the evidence obtained there and later confirmed by the experimental work of Fairleythat Atabrine suppression. at the rate of one tablet a day, will not preventinfection with falciparum malaria but will hold it in a subclinicalstate and eventually cure it; and the studies made, on the instigation ofCol. Earle MI. Rice, MC, by the hospitals in Base 3 (Brisbane) on the characteristics of the New Guinea variety of tertian malaria. It was on the proof afforded by these studies, and by the parallel studies in Australian hospitals onAtherton Plateau, that the determination was reached that the relapse rateof this type of malaria was so high that, if troops were to be kept in combat-worthy condition, con-
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FIGURE 61.- Cartoon, "Don't Be A Dunce."
tinuous Atabrine suppression of malaria-infected units might be maintained not only in New Guinea but in Australia as well. 26
PERSONNEL TRAINING
The enforcing of effective personal measures for the prevention of malaria was the greatest problem of the control program in this theater. It was essential that both officers and enlisted men receive frequent reminders of precautions to be observed. To aid unit commanders in this, malariologists were available in a majority of the forward areas. Two antimalaria schools, one in NewGuinea and one on the Australian mainland, were established for the instruction of medical officers as well as officers of all other branches. Schools for instruction of company or unit antimalaria details were conducted by malariologists and the officers and men of the malaria survey unit and malaria control unit in the area. Training Films 8-953, "Malaria, Cause and Control," and 9-953 A, Walt Disney's "Winged Scourge," were widely shown in forward areas and in the antimalaria schools. The use of roadside signs with pertinent slogans were of great value in the educational campaign. Several posters were produced in this theater for unit bulletin boards (figs. 61, 62, and 63).
26 (1) Fairley, N. H.: Chemotherapeutic suppression and Prophylaxis in Malaria. Tr. Roy. Soc. Trop Med. & Hyg. 38 : 311-365, May 1945. (2) Fairley, N. H.: Atabrine Susceptibility of the Aitape-Wewak strains of P. falciparum and P. Vivax. Tr. Roy. Soc. Trop. Med. & Hyg. 40: 229-273, December 1946. (3) Fairley, N. H.: Sidelights on Malaria In Man Obtained by Sub-Inoculation Experiments. Tr. Roy. Soc. Trop. Med. & Hyg. 40: 621-676, May 1947.
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FIGURE 62.- Cartoon, "Patch That Net Hole Today."
FIGURE 63.- Cartoon, "Watch Out for This Chow Hound."
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SWPA Malaria Schools
A malaria control training school was organized at Brisbane, began instruction in September 1943, and continued for almost a year. Two sessions were held each week, one for line officers and one for medical officers. With an average of 15 to 20 officers in each class, a total of 1,500 to 2,000 attended the school. In 1944, the school was transferred to Finschhafen, New Guinea, as troops for the United States were then arriving there instead of Brisbane. A school offering courses for medical and line officers was started at Base A inMarch 1944, and later a course for nurses was introduced. Some 851 officersand nurses received instruction.
This theater found that visual education was a very important feature in the forward areas. "Sign board" education was highly developed because of the shortage of training films with (1) dock signs wherever troops landed, stressing that this is a highly malarious area and asking cooperation, and (2) road signs of many varieties. Some areas used "Burma Shave" type signs; others used pictures of clothed and practically unclothed female figures. All signs and wording utilized were suggested by the enlisted men. It was realized that paintin assorted colors, and brushes, should be part of the table of basic allowances of every control and survey unit.
As the essence of environmental control was found to be the checking of areas for breeding, one personable enlisted man from each control unit was assigned as liaison man. His sole job was to create good will, inspect the work of unit antimalaria details, furnish equipment and supplies in emergency, and collect essential supplies for his own unit.
All ships were boarded on arrival by assistant malariologists, and commanding officers of units were contacted about Atabrine discipline, clothing, mosquito nets, and all other antimalaria supplies.
A popular measure for promoting oiling work by unit antimalaria details was the practice of running a repair shop for knapsack sprayers by malaria control units.
COMBAT EXPERIENCES AND LESSONS
Malaria control programsvaried with local conditions but always included (1) measures directed againstthe breeding of mosquitoes and (2) the enforcement of individual disciplinewith reference to the use of Atabrine and to exposure to mosquitoes. As garrisonconditions became stabilized, more attention was given to the adjacent nativepopulations which were often heavy reservoirs of infection.
The disastrous effects of malaria on the effectiveness of combat divisions can be illustratedby citing the experiences of several divisions during the campaign to prevent the Japanese from reaching the Australian mainland. It was essential that crucial areas in New Guinea should remain in Allied possession. The strength of the forces available was limited and the loss of
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combat troops due to malaria could not well be afforded, but no organization existed at that time which could be effective in control under existing conditions.
Four divisions--the 1st and 2d Marine Divisions and the U.S. Army 32d and Americal Divisions--were rendered noneffective by malaria for a period of 4 to 6 months after withdrawal from the combat area. The 41st Division, which had engaged in 76 days of continuous combat. around Sanananda Point, Dobodura, and Buna, reported 3,824 persons, or 27.7 percent of the command, as having one or more attacks of malaria. The XIV Corps lost the equivalent of an entire infantry battalion each month from malaria, and between October 1942 and April 1943, 30 percent of all hospital admissions in the South Pacific Area were due to malaria.
During the year 1943,the Southwest Pacific reported 47,663 cases of malaria and 13,230 admissions for fever of undetermined origin. In a group of cases studied, the average hospitalization for a case of malaria was 15.24 days; 10 percent of thecases returned to duty in 7 days; 25 percent, in 10 days; and 50 percent,in 13 days.
In the 10-month periodsubsequent to its withdrawal from New Guinea, 67 percent of the 32d Divisionmanifested clinical symptoms of malaria. Over 80 percent of the 1st MarineDivision was hospitalized for malaria within 9 months of the beginning ofthe Guadalcanal Campaign.
To illustrate the saving in hospital beds due to effective malaria control, it has been computed that, if the malaria (plus 75 percent of the fevers of undetermined origin) rate had been as great in February 1944 as in February 1943, 10,955 hospital beds would have been required for such cases. Instead, at the later date, only 1,324 beds were actually occupied, representing a saving of 9,631beds due to effective malaria control measures.
The two primary factorsthat were responsible for the lowered malaria rates after February 1943 were(1) the assignment of adequate priorities for movement of antimalaria suppliesand personnel from the United States and within the theater, and (2) an efficientantimalaria organization which resulted in better malaria discipline, increasinglysuccessful administration of suppressive Atabrine, and more effective antimosquitowork of all kinds.
The use of drugs to suppress attacks of clinical malaria was absolutely necessary in operational areas where malaria threatened, but since its action was to prevent clinical symptoms of the disease without preventing the infection, the Army could not know the extent to which malaria was being transmitted in theaters of operations. That transmission continued was certain and that it would greatly increase where antimosquito work was relaxed was even more certain.
Atabrine in daily doses of 0.1 gm. prevented the appearance of clinical symptoms of malaria as long as the drug was continued. No evidence, however, was obtained that Atabrine in suppressive doses even for long periods cured vivax malaria. It was found that, after the drug was stopped, relapses
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usually occurred within 1 or 2 months, but sometimes much later. There was no evidence that the number of relapses expected after a long period of suppression differed materially from the number expected without suppression. Infections of falciparum malaria, on the other hand, were usually cured by the suppressive drug when it was continued for 4 weeks beyond the last exposure. Suppressive Atabrine was the rule in the Southwest Pacific except for Australia.
It was necessary that drug suppression of malaria continue to be used to reduce noneffectiveness in certain military situations, but it was realized by all concerned that infection with vivax malaria was not prevented thereby and that there was no substitute for control of actual transmission. This entailed fulluse of malariologists and malaria control and survey units to determine therisk and to plan and execute programs of prevention. Mosquito control waseffective in proportion to the skill and the energy with which it was plannedand applied. Improved repellents, insecticides, and suppressive drugs wereavailable in the field. Vigilance in the supervision of the individual protectivemeasures of proper clothing, use of bed nets and sprays, application of repellents, and avoidance of native habitations kept down the attack rate in malarious areas.
In the 31 July 1945 issue of Health, page 11, it was stated:
Malaria remains aconstant threat to the effective strength of the Army. While the current lowadmission rates prove that malaria is no longer out of control, which wasthe case in 1943, they cannot be used as evidence that the problem has beenentirely solved. Low rates will continue only so long as effective atabrine discipline and mosquito control measures are rigidly enforced. The invasion of Luzon has again demonstrated that advance into malarious areas may be expected to increase admission rates considerably. In January 1945, therate for the Southwest Pacific stood at only 27 per 1,000 men per year,but by April it had reached 75; and for troops in the Philippines the rateswere even higher, although but a fifth of those prevailing at the end ofthe Buna-Gona campaign. However, because of the success which can be achievedwith rigorous atabrine discipline even continuously low malaria admissionrates do not rule out further malaria transmission on a large scale. Undercombat conditions, as on Luzon, any lapse in atabrine suppression may costheavily in clinical malaria.
A good description of operational lessons that can be learned from a military campaign insofar as disease prevention is concerned was stated in the 30 November 1943 issue of Health. In malaria control, it was emphasized, the combat division needs experienced malaria survey and control units to follow it immediately into combat if the incidence of malaria is to be held to a minimum and the fighting man to be kept on his feet. It was further pointed out that malaria incapacitated; it put out of action whole divisions for many months. Contrasted with this picture was the fact that malaria could be prevented and suppressed. The great lesson learned was that the most effective control of malariawas the prevention of infection. Although group methods of environmental sanitation and control were highly effective, under combat conditions it was largely what the individual soldier did for his own protection thatcounted most heavily in keeping down malaria infection. Unless the
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soldier knew how to protect himself with the means provided, he could be expected to contract malaria in a short time in a highly malarious area. For these reasons, malaria control wasdetermined to be primarily a command function, necessitating the maintenance of a high state of malaria discipline. If the commanders did not enforce control measures, they jeopardized the success of their military mission.
CASE STUDY OF MALARIA INCIDENCE
The malaria experience on Kiriwina Island is typical for the islands off New Guinea during 1943. A study of causes was made, in which most cases of malaria among U.S. troops were interviewed by an officer in order to determine the reason for their having become ill with malaria. Other enlisted men of their organization were then interviewed to substantiate histories. In a number of instances, defects in malaria discipline, especially Atabrine suppression, may have been the cause. It was found that, in some instances, officers did not supervise the suppressive treatment; it was left to the enlisted man to decide if he should take the Atabrine as he passed through the mess line. It was also found that most malaria cases among the mess personnel probably resulted fromlack of supervision and that men on outpost duty were occasionally not wellsupervised. Repellent often was not used by the men, usually they did nothave it readily available. It was believed that much of such failure in malariadiscipline could be eliminated if an alphabetical roster were kept in eachorganization to determine whether each enlisted man had actually swallowedhis Atabrine tablet and whether he carried a bottle of repellent with himat evening mess. 27
CASE REPORTING
As the incidence of malaria reached high proportions in the early part of 1943, consideration was given to securing adequate and timely reporting of its incidence. None of the Medical Department reports then in use gave complete coverage of all the facts considered necessary. The statistical report gave only a crude attack rate, with no differentiation between primary and recurrent attacks, and with no clue as to the prevalent types of infecting parasites. Thefield medical records (WD MD Forms 52b and 52c), which passed through theCentral Medical Records Office, had an average timelag approaching 6 weeksbetween the dates of an attack and of information reaching the Chief Surgeon.These records did not always include statements on the type of infectionor the status of attacks.
A malaria case report card was designed by the theater Chief Medical Inspector in the early part of 1943. This card was approved by the theater
27 Inspection Report No. 1, Office of the Surgeon, Headquarters, Sixth U.S. Army, dated 11 Oct. 1943, subject: Summary of Malarial Survey of Kiriwina Island for September 1943.
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Chief Surgeon and the Combined Advisory Committee on Tropical Diseases, the latter adopting the card as the standard method of reporting malaria for all Allied troops in this theater. The initiating directive together with a supply of the cards was distributed to field units in May and June 1943. The first reports using these cards were receivedfrom the field the latter part of June 1943. The units in New Guinea andadjacent islands forwarded the cards to the Central Medical Records Office,Office of the Chief Surgeon, APO 501, through the office of the assistantmalariologist, Base B, APO 503. Malaria case report cards from units inAustralia were sent direct to the Central Medical Records Office.
Before 15 June 1943, the Central Medical Records Office maintained a locator file for patients of hospitals, based upon the admission and disposition sheets. The field medical records were checked, pertinent information was transcribed fromthe locator file cards, and placing the cards from "active" to the "inactive" section of the locator file was carried out as necessary. Consequently,there existed in this office a fairly reliable basis for the compilationof malaria statistics, at least with respect to unit incidence rates andthe number of attacks suffered by given individuals. The locator file wasdiscontinued in the Central Medical Records Office and a file of extractsin the field medical records was instituted for malaria cases only.
In order to compile the individual records, a malaria case summary card record was designed and adopted as a means of condensing the information. This condensation of records was instituted in November, and soon after, case summary cards were completed on approximately 75 percent of the cases in the file. Summary cards were posted as the malaria case report cards were received. These postings were later checked or revised as necessary when the field medical records were processed.
Comparison of field medical records processed in this office with the malaria case summaryfiles indicated that approximately 30 percent of the diagnosed malariawas not reported by the malaria report card. This was due in some degreeto the fact that hospitals and medical detachments arriving in the theaterwere not familiar with the form, to the problem of distributing cards sothat they would be available to all units at all times, and to the reluctanceof seine medical officers to do additional paperwork.
REDUCTION IN HOSPITALIZATION
It was felt that the reduction in the hospitalization time of malaria cases was particularly significant. An analysis of the factors involved showed that the treatment of malaria in SWPA may be divided into certain definite periods. During the first period, which ran from November 1942,. when malaria cases in significant numbers were first admitted to hospitals, until April 1943, the treatment generally followed was that recommended in Circular Letter No. 135, Office of The Surgeon General, 21 October 1942. This course of treatment
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(QAP: quinine-Atabrine-Plasmochin) lastedfor 15 to 17 days and was not followed by a period of followup or suppressivetreatment. The ineffectiveness of this treatment led to a certain numberof intercurrent recrudescences of fever usually during the period of Atabrineadministration. In these cases, the total time of treatment was lengthened.
More important was the fact that, as a consequence of stopping all drugs after the activecourse was completed, early relapses occurred within the first month inat least one-half of the cases. Many of these relapses appeared while thepatient was still in the hospital and led to a repetition of the initialcourse of treatment. The patients, during this period, were chiefly fromthe 32d Division, fighting in the Buna-Gona Campaign, and from the 1st MarineDivision brought to Australia after the battles of Guadalcanal. Malnutritionhad greatly weakened these men, and their stay in the hospital was oftenlengthened for the purpose of building up their weight and strength. Furthermore,the proportion of battle casualties among the malarious patients was higherat this period than in the later months of 1943, and longer hospitalizationwas frequently necessary because of wounds. In certain hospitals, necessaryinvestigations of convalescents after malaria led to retention of patientsfor observation.
Circular No. 15, USAFFE, 12 April 1943. "Treatment of Malaria," prescribed a change in routine treatment and initiated the second period. The 2-day rest period without drugs which was a feature of the previous QAP treatment was eliminated, thus reducing hospitalization by 2 days. Furthermore, the new regimen included a 6-week period following active treatment in which 0.1 gm. Atabrine was given on 6 days of each week. this followup treatment practically stopped the occurrence of relapses in hospitals and greatly shortened the average hospital stay. In this period, battle casualties were few and the nutrition of troops improved. There was therefore less cause to prolong the hospital stay of malaria cases because of wounds or physical weakness of the patient.
An amendment to CircularNo. l5 initiated the third stage.28 It changed the treatment ofthe malaria attack to the intensive Atabrine treatment of 6 days duration, thereby reducing hospital stays for active treatment from an average of13 to 6 days. Control experience in hospitals, in the Sixth U.S. Army Training Center, and in field units had shown by this time that brief hospitalization after subsidence of fever caused by malaria was all that was required.In fact, weight increase, strength, and morale were aided by early removalfrom the hospital atmosphere. In particular, the fact that repeated prolonged hospitalization for recurrent malarial attacks tended to induce neurosisin the affected soldier was taken into consideration.
Between January andJuly 1944, the proportion of malaria cases which were also battle casualties had again increased. This tended to lengthen the hospital stay. In summary, therefore, the chief factors in reducing the length of hospital stay for malaria attacks were as follows: (1) The successive short-
28 Circular No. 72, Headquarters, USAFFE. 7 Sept. 1943.
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ening of prescribed routine treatment, (2) the followup with suppressive Atabrine treatment, and (3) the growing realization that the average malaria attack, properly treated, produces comparatively slight aftereffects on the patient.29
JAPANESE MALARIA EXPERIENCE
A Japanese Medical Department report captured at Munda, on New Georgia, makes possible interesting comparisons between Japanese troops in the Eighth U.S. Army area and American troops on New Guinea. The report gives detailed data for February 1943 and a summary for December 1942 and January 1943.30
At the time the reportwas prepared, Japanese troops had been in the Rabaul area for at least 8months, and their estimated average strength was 51,382 in December and 79,901in February. The strengths are "estimated" in the sense that the translation mentions the number of "personnel examined." It is assumed that this number is the strength of the force from which the admissions were drawn. Thearea was served by two base hospitals having, with their annexes, a combinedcapacity in excess of 4,000 beds. Altogether, including an unspecified numberof field hospitals, there were at least 8,800 beds, or about 11 percentof the troop strength, during February. During the 3-month period, the health of the Japanese troops was considerably less favorable than was that ofthe U.S. forces on New Guinea. For all causes, including battle casualties,the average admission rate for the entire period was 4,086 per 1,000 menper annum for the Japanese troops, approximately twice that experiencedby the American units.
Malaria was the greatestsingle cause of admission and noneffectiveness among Japanese troops duringthis period, causing 17,112 new admissions and 5,415 readmissions. This numberof cases represents 37 percent of the mean strength and 35 percent of alladmissions for the 3 months. During the same period, diagnosed malaria accountedfor 34 percent of all admissions among U.S. troops on New Guinea. The averageadmission rate for malaria was 1,440 per 1.000 men per annum for the Japaneseand 718 for U.S. troops, if only diagnosed malaria be counted. The averagenoneffective rate for malaria among the Japanese troops was roughly 40 per1,000 men per day.
Chart 26 compares Japanese and American admission rates for several diagnoses during February 1943. The Japanese rate for malaria has been separated into two parts, representing new patients and old patients, while the rate for U.S. forces on New Guinea shows the incidence of diagnosed malaria together with an increment representing three-quarters of the admissions for fever of undetermined origin. The comparison of the malaria admission rates depends to some extent upon the completeness of diagnosis. It was customary
29 Essential Technical Medical Data, Southwest Pacific Area, for July 1944, dated 5 Aug. 1944, pp. 3-5.
30 Monthly Progress Report, Army Service Forces, War Department, 30 Nov. 1943, Section 7: Health, pp. 12-13.
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CHART 26.-Japanese and U.S. admission rates during February 1943
at U.S. headquarters in SWPA to assume that about three-quarters of the admissions for fever of undetermined origin were probably malaria. The Japanese report made no mention of fever of undetermined origin, and the completeness with which malaria was diagnosed by Japanese medical officers was not known. The Japanese rate, however, must be taken as a minimum if it is to be compared to the estimated total malaria ratefor U.S. troops. The moderately high incidence of beriberi among the Japanese was of interest inasmuch as statements of prisoners of war and capturedenemy equipment and supplies all indicate that the Japanese were very "vitaminconscious."
During February, 3,776 Japanese troops were treated for enteric diseases, representing a rate of 615 per 1,000 men per year. On 22 March, there were 37 Japanese hospitalized for typhoid fever, 146 for paratyphoid, and 140 for dysentery. The number of cases reported was of interest in view of the fact
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that Japanese were known to be conducting an immunization program against these three diseases.
At the end of February 1943, there were 72,916 Japanese troops in the Rabaul area, 20 percentof whom were receiving medical care.
OTHER ACTIVITIES OF THE MALARIA CONTROL ORGANIZATION
The sanitary engineering, entomological, medical, and other trained personnel engaged in malaria control had skills which qualified them for many other duties.
Scrub Typhus Control
For instance, malaria units assisted in controlling scrub typhus, which was a serious problemin the early days in New Guinea. It was found that dimethyl phthalate readily killed the mite transmitting this disease. Earlier, various methods hadbeen used to safeguard campsites, such as burning the kunai grass and stripping the sod from the area by bulldozer and other heavy equipment. Experimental work by entomologists indicated that dipping clothing in dimethyl phthalate killed the mites before they could bite. From this work, methods were developed which provided a high degree of protection against this disease.31
Filariasis Control
Filariasis was a disease of importance in some areas of SWPA. Existing malaria survey units were used on occasion, in coordination with sanitary engineering personnel, for the control of this disease. Experience indicated the desirabilityof establishing special units to combat this disease.32
Rodent Control
A school for rodent and flea control was proposed as a means of expanding the preventive medicine duties of malaria survey and malaria control units.
With the approval of the Chief Surgeon, USASOS, the first class of the Rodent Control School was started on 12 March 1945. The period of instruction was for 2 weeks. The personnel attending the first class were the officers and enlisted men of the 93d Malaria Control Unit and the 211th Malaria Survey Unit. Subsequent classes were conducted each 2 weeks, beginning on 2 April 1945.
31 Philip, Cornelius B.: Scrub Typhus and Scrub Itch. In Medical Department, United States Army. Preventive Medicine in World War II. Volume VII, Communicable Diseases: Arthropod-borne Diseases Other Than Malaria. [In preparation.]
32 Swartzwelder, Clyde: Filariasis Bancrofti. In Medical Department, United States Army. Preventive Medicine in World War II. Volume VII. Communicable Diseases : Arthropod-borne Diseases Other Than Malaria. [In preparation.]
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Although written late in 1945 when no longer in SWPA, the report of the 6th Malaria Survey Detachment is interesting because it illustrates the rodent control activities carried on by these units.
Upon arrival in Japan,personnel of the 6th Malaria Survey Detachment were engaged in conducting rodent and flea surveys of Kyôto and vicinity. The primary purpose of such surveys was to determine the following:
1. Density of rat population.
2. Species of rats present.
3. Density of fleas.
4. Species of fleas.
5. Presence ofother household pests.
In the initial stages of the survey, many Japanese buildings, such as Japanese Army barracks,were examined thoroughly for evidence of rats, fleas, and other householdpests. In many instances, these installations were inspected before beingoccupied by U.S. Army troops. However, a small number of units had the unfortunate experience of occupying Japanese Army barracks before they were inspected. Because of this, many soldiers suffered considerably from the bites offleas and bedbugs. On a number of these inspections, the survey party wasaccompanied by a member of the 10th Malaria Control Detachment, so thata more thorough spraying job was accomplished. Nearly all of the infestedinstallations were sprayed with DDT before occupation by Army troops.
Dengue Fever
Malariologists, malariasurvey and malaria control units were concerned with the control of denguefever as well as scrub typhus and filariasis control. Their primary concernwas eradication of breeding areas of the vectors concerned.33
Sandfly Fever Control
In its quarterly report, 1 July to 30 September 1944, the 5th Malaria Survey reported that the sandfly Phlebotomus was common in New Guinea. Members of the unit visited practically every base in New Guinea, save one, and some of thenearby islands. Sandflies were taken at each base. Phlebotomus werecollected in tree holes and on the shaded sides of tree trunks and buttresses.The method of collection was to spread a white sheet at the bottom of a tree hole, or on the ground around the tree trunk, or between the buttresses and then spray these areas thoroughly with an Aerosol Freon dispenser.Specimens of these midges were sorted from the collection of all smallinsects that fell on the sheet.34
33 (1) Essential Technical Medical Data, Southwest Pacific Area, for May 1944, dated 5 June 1944, p. 8. (2) McCoy, Oliver R., and Sabin, Albert B.: Dengue. in Medical Department, United States Army. Preventive Medicine in World War II. Volume VII. Communicable Diseases : Arthropodborne Diseases Other Than Malaria. [In preparation.]
34 Hertig, Marshall: Sandfly Fever. In Medical Department, United States Army. Preventive Medicine in World War II. Volume VII. Communicable Diseases: Arthropodborne Diseases Other Than Malaria. [in preparation.]
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Related Activities
The 5th Malaria SurveyUnit arrived in the area, Leyte Island, Philippines, on "A" Day, 20 October1944. Attached to the 24th Infantry Division, the organization was engagedin sanitation work in the town of Palo on 1 November 1944.
No Malaria control work was done during the month. The units trucks and drivers were utilized by the 24th Infantry Division to haul supplies and personnel. The quartermaster attached one weapons carrier and driver to the 101st Graves Registration at Carigara from 1 November through 14 November.
While bivouacked on the beach, two of the units trucks and drivers were furnished to haul ammunition and supplies to the frontlines. A weapons carrier with driver and 30 shovels was furnished to a division burial detail from 26 October tothe close of the month. The unit personnel supervised 14 Filipino laborers in digging latrines and other sanitation work for the civilian population in the overcrowded town of Palo from 27 October to the close of the month. Official war photographers took some movies and stills of this work. The dumptruck and driver were furnished to the 36th Evacuation Hospital on 30 and31 October for hauling gravel. No malaria control work was done.
In the Philippines, the malaria survey and malaria control units expanded their activities into a variety of public health activities, such as the survey control and education on schistosomiasis for Army personnel and civilian populations. They also became involved in restoring and operating municipal water supplies andsewage disposal plants. garbage collection and disposal, latrine building for large segments of the civilian population, sanitary inspection of restaurants, hotels, abattoirs, bakeries, and food processing plants, to mention but a few of the manifold duties. Later on, some of the Sanitary Corps officers who commanded these units were chosen for military government work and continued these important functions in the Philippines, Japan, and Korea after termination of hostilities in World War II.
SURVEY AND CONTROL UNITS
As of 25 September 1944, there were 58 malaria control and 26 malaria survey units assigned to USAFFE. Of these, 21 control and 13 survey units were with the Sixth U.S. Army, from Oro Bay to Biak. There were 10 control and 4 survey units with the Fifth Air Force; 5 control and 3 survey units with the Thirteenth Air Force; and 22 control and 6 survey units with USASOS. In addition, there were 7 control and 6 survey units located in the Southwest Pacific whichhad been assigned to but had not yet arrived in SWPA. Total in the theaterand assigned to it were 65 control and 32 survey units, on 25
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September 1944. In comparison, on 25 September 1943, there were 12 control and 5 survey units in SWPA.
Several malaria controlunits that had difficulty in obtaining the equipment for beginning theirwork at once emphasized the importance of the units being shipped and movedwith all their equipment. Several units felt that a combination of a controland a survey unit would be desirable, with equipment including trucks, jeeps,spray outfits, electric generator units, tents, and necessary office suppliesand equipment. Prompt initiation of control measures after establishmentof a beachhead was emphasized many times. It was also suggested that theattachment of enlisted personnel to the combined control survey unit wouldpermit more effective and expeditious work. The attachment of units to commandsso that they would he a definite part thereof was generally favored. It wasfelt that this would result in more adequate facilities for doing necessarywork.
FINAL RESULTS
As a result of the control program in the Southwest Pacific, military operations after themiddle of 1943 were not seriously handicapped by malaria. The campaign inthis area was the first one in which so many U.S. Army troops had foughtunder such highly malarious conditions. The lack of experience in controllingmalaria under combat conditions, the absence of any organization suitablefor control, and the mental unreadiness of both combat and medical officersrepresented very serious problems which had to be, and were, overcome.
Numerous examples have been cited throughout this history which show the results obtained in reducing the incidence of malaria. A few examples will be repeated here. In January 1943, U.S. troops in the Milne Bay area had a malaria attack rate of 3,308 per 1,000 men per annum. In January 1944, the rate was 30.7. In February 1943, the malaria attack rate in the command strength of SWPA (including 75 percent of fever of undetermined origin) was 794 per 1,000 men per annum; in February 1944, it was 179. This reduction in malaria rate represented a saving of more than 9,600 hospital beds.
The primary lessons learned were that effective control must be based on (1) utilization of all methods, including larva and adult control, the use of suppressive medication, troop education and discipline, and the employment of a special controlorganization utilizing engineering, medical, entomological, and other skills;(2) area-based control, not control on a unit or force basis; and (3) unifiedauthority and control, to insure that all necessary phases of the programare carried on in all areas that threaten troops.
The malaria attack rates among U.S. Army personnel, in the Southwest Pacific Area, by type of Plasmodium and year of admissions are shown in table 79. Table 80shows deaths due to malaria by type of Plasmodium and year of death.
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