Parasitic Infections
CHAPTER XXIII
Amebiasis
Henry E. Meleney, M. D.
Before World War II, amebiasis lead not been aserious problem ill the United States ArmedForces, except during the Philippine Insurrection following theSpanish-American War and inone epidemic oil the Mexican border in 1916. Attention has been calledto these two episodes byCraig.1 During World War I among AmericanArmed Forces,2 only 38 out of 934 laboratorytested cases of dysentery were proved to be of amebic; origin. The onlyindication of acquisitionof infection with Endamoeba histolytica overseas was furnishedfrom a fecal survey atDebarkation Hospital No. 3 by Kofoid, Kornhauser, and Plate3in which they found 12.8 percentof 2,300 overseas troops infected, as compared with 4.3 percent of 576troops who had not beenoverseas.
The British lead considerable experience with amebiasis during World War I especially in the Gallipoli campaign and in the Middle East. This led to intensive studies of intestinal amebiasis of man and to the discovery of two previously unrecognized species, Endolimax nana4 and Dientamoeba fragilis.5 Within the next 20 years, surveys of the prevalence of amebiasis were made ill many parts of the world including several ill the United States, and Craig estimated that the over-all prevalence in this country was about 10 percent of the population with wide variations in different regions.
Many other important contributions to the knowledge of amebiasis were made between the First and Second World Wars. In 1925, Boeck and Drbohlav 6 devised a practical culture medium for E. histolytica, and this was improved upon by Dobell and Laidlaw. 7 In 1929, Craig 8 described a comple-
1 Craig,Charles F.: TheEtiology, Diagnosis, and Treatment of Amebiasis. Baltimore. Williamsand Wilkins Co.,1944. (2) Craig, C. F.: The Occurrence of Endamebic Dysentery intheTroops Serving in the El Paso District FromJuly 1916 to December 1916. Mil. Surgeon 40: 286-302;423-434, March and April 1917.
2 TheMedical Departmentof the United States Army in the World War. Washington:Government PrintingOffice, 1926, vol. VI, p. 1101.
3 Kofoid,C. A., and Kornhauser, S.I., and Plate, J. T.: Intestinal Parasites in Overseas and Home ServiceTroops ofthe U. S. Army; With Especial Reference to Carriers of Amoebiasis. J.A.M. A. 72: 1721-1724, June 1919.
4 Wenyon,Charles M., andO'Connor, Francis W.: Human Intestinal Protozoa in the NearEast.London: John Bake,Sons and Danielsson, 1917.
5 Jepps,M. W., and Dobell, C.: Dientamoebafragilis, a New Intestinal Amoeba From Man. Parasitology 10:352-367,1917-18.
6 Boeck,Ii'. C., andDrbohlav, J.: The Cultivation of Endamoeba histolytica. Am. J.Hyg. 5: 371-407, July 1925.
7 Dobell,C., and Laidlaw, P. P.: Onthe Cultivation of Entamoeba histolytica and Some OtherEntozoic Amoebae.Parasitology 18: 283-318, September 1926.
8 Craig,C. F.: The Technique andResults of a Complement Fixation Test for the Diagnosis of InfectionswithEndamoeba histolytica.Am. J. Trop. Med. 9: 277-296, September1929.
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ment fixation test for amebiasis. Dobel l9 I worked out thelife cycle ofE. histolytica in culture.Studies of pathogenicity were made in kittens10 and dogs,11and the influence of associatedbacteria and diet received attention. The Chicago epidemic of 193312emphasized the importanceof contaminated water as a source of infection. Studies of waterpurification indicated that cystsof E. histolytica are more resistant to chlorination than arefecal bacteria.13 Chemotherapy wasimproved by the introduction of carbarsone and the iodohydroxyquinolinecompounds,chiniofon, Vioform, and Diodoquin. The zinc sulfate flotation techniquefor concentration ofcysts in fecal diagnosis was introduced.14
INCIDENCE
General Considerations
The incidence of amebiasis in the Army includedmild cases of amebic dysentery and amebiccolitis as well as those with the classical picture ofdysentery.Available statistics for the Armyhave been obtained from sample tabulations of primary and secondarydiagnoses on individualmedical record cards and include admissions for amebic dysentery aswell as cases admitted fordifferent diagnosis but in which amebic dysentery existed concurrentlyor developed subsequentto admission. Although dysentery is the most prominent clinicalmanifestation of amebiasis andis a good measure of its importance as a cause of noneffectiveness, itrepresents only a smallproportion of the infections with E. histolytica. This isimportant because these infections areusually of long duration, probably many years, and are the source ofspread to contacts undersuitable circumstances. Furthermore, symptomless infections may giverise to clinicalmanifestations only after a long period of time.
Preliminary statistical data on the incidence (total cases) of amebic dysentery in the United States Army for the years 1942-45 by area, as calculated from samples of individual medical records, are presented in tables 84, 85, 86, and 87. These estimates, though subject to considerable sampling error, furnish comparative information of value concerning the relative importance
9 Dobell,C.: Researches on the Intestinal Protozoa of Monkeys and Man. II.Description of the Whole-Life-Historyof Entamoeba histolytica inCultures. Parasitology 20:365-412, December 1928.
10 Meleney, H. E., and Frye, W.W.: ThePathogenicity of Endamoeba histolytica.Tr.Roy. Soc.Trop. Med. & Hyg. 29: 369-379, January 1936.
11 Faust,E. C., and Kagy, E. S.: Studies on the Effect of Feeding Ventriculin,Liver Extract and Raw Liver to DogsExperimentally Infected With Endamoeba histolytica.Am. J. Trop.Med. 14: 235-255, May 1934.
12 EpidemicAmebic Dysentery: The Chicago Outbreak of 1933. Nat. Inst. Health Bull.No. 166, pp. 1-187, March1936.
13 Chang,S. L., and Fair, G. M.: Viability and Destruction of the Cysts of Entamoebahistolytica.J. Am. WaterWorks Assoc. 33: 1705-1715, October 1941.
14 Faust,E. C., D'Antoni, J. S., Odom, V., Miller, M. J., Peres, C., Sawitz, W.,Thomen, L. F., Tobie, J., and Walker,J. H.: A Critical Study of Clinical Laboratory Techniques for theDiagnosis of Protozoan Cysts and Helminth Eggsin Feces. Am. J. Trop. Med. 18: 169-183, March 1938.
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TABLE 84.- Incidence of amebic dysentery in the U.S.Army, by area and year, 1942-45
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of amebic infection as a cause ofnonefectiveness in the Army. The following observationson these figures are of interest:
1. The over-all rate of 1.34 per1,000 average strength is low as compared with that of manyother infections requiring medical attention.
2. The rate each year more thandoubled the rate of the previous year.
3. The rate for troops in the UnitedStates was uniformly very low, increasing only in 1945 whenmany overseas troops had returned to this country.
4. Among the overseas theaters, theChina-Burma-India theater had by far the highest rate, withthe Middle East theater second, and the combined Pacific theatersthird. The rates in the otheroverseas theaters never reached important proportions.
TABLE85.-Admissions for amebicdysentery in the U. S. Army, byarea and year, 1944-45
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TABLE86.- Admissionsfor amebicdysentery carrier in the U. S. Army, by area and year,1942-45
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TABLE87.-Incidenceof amebicdysentery carrier state in the U. S. Army, by area andyear, 1944-45
AMEBIASIS IN OVERSEAS THEATERS AND AREAS
India-BurmaTheater
Amebic dystenterywas recognized andreported in Army units soon after they began to arrive inthe theater in the summer of 1942.15 Itincreased moderatelyin incidence during 1943 and morein 1944 reaching a peak of 50 per annum per 1,000 average strength inAugust and September1944. This represented 675 and 884 cases, respectively, in these 2months. In 1945, the incidencedecreased considerably when intensive measures to prevent diarrhealdiseases became effective.It is interesting that the incidence of bacillary dysentery was almostconsistently somewhat lowerthan that of amebic dysentery throughout the entire period ofoperations in this theater. Both ofthese infections, however, were greatly overshadowed by acute diarrheaof unrecognizedetiology, which reached a peak incidence of 215 per annum per 1,000strength in July 1944.
Insanitary conditions conducive tothe transmission of amebiasis existed almost everywhere inthe theater. The medical and sanitary departments
15 Van Auken, H. A.: A History of Preventive Medicine in the U. S. Army Forces of the India-Burma Theater, 1942-45. [official record.]
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were not prepared to deal with thiscomplicated problem. Most medical officers had had nopractical experience in dealing with the type of environmentalconditions which existed andcould not foresee or detect the hidden sources of infection. Directivesfor prevention and controlwere general in nature and not specifically adapted to the localsituation. Equipment for messsanitation, fly control, and water purification was inadequate or notefficiently used. Facilitiesfor accurate diagnosis were provided only at the 9th Medical Laboratoryand at some of thegeneral hospitals.
As experience was gained by investigation of conditions associated with high incidence or epidemics of diarrheal diseases in individual units, unsupervised native foodhandlers appeared to be the greatest source of infection, although surveys for E. histolytica regularly showed a much lower incidence of infection in natives than in American personnel. In two instances, however, contaminated water supplies appeared to be the source of outbreaks of amebic dysentery. Other possible sources of infection were difficult to evaluate.
In June 1944, thePreventive MedicineService of the Surgeon General's Office. sent a Sub-Commission onDysentery of the Army Epidemiological Board to Calcutta to make anintensivestudy in that area and in the Ledo area of Assam. The Sub-Commission16reported that at the112th Station Hospital in Calcutta during July 1944 about one-fourth ofthe admissions fordiarrhea or dysentery were amebic. In Advance Section 3 (Assam) for theyear ending 30September 1944, there had been 444 hospital admissions for amebicdysentery. In one combatunit, one-third of the first 150 admissions were for amebic dysenter.The Sub-Commissionconcluded that, from the standpoint of days lost and disability,amebic dysentery was the mostimportant of the diarrheal diseases.Trained clinical and laboratorypersonnel and equipment foraccurate diagnosis were inadequate, and sources of infection werepoorly controlled.The chiefsource appeared to be native foodhandlers, followed by water, flies,and food in order ofimportance. Instruction of personnel was started, and recommendationswere made for morerapid and accurate diagnosis, additional trained personnel, thoroughtreatment, and the control ofpossible sources of infection.
A preventive medicine section was set up in the Office of the Chief Surgeon and certain control activities were initiated through the theater commander. Among these were the assignment of a special sanitary officer to check mess sanitation through the theater, the issuance of letters of inquiry, to orgailizations with high diarrheal rates, the inauguration of a better method for the distribution of sanitation supplies, and the preparation of a circular on water supplies.
The complete program of control instituted in the fall of 1944 included the issuance of directives, periodic inspections, provisions of necessary supplies, education of commanders and lectures to personnel, investigations of undue increase of cases of diarrhea, and the placing of responsibility for control on unit commanders. A theater laboratory consultant was appointed to raise
16 Progress and Final Report, Sub-Commission onDysentery, Army Epidemiological Board, 20 Nov. 1944.
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the standards of diagnosticperformance throughout the theater, and the 9th General Laboratorygave apprentice training and longer courses of instruction tolaboratory officers and enlistedmen.
The problem of symptomless carriers of E. histolytica among American personnel and natives received considerable attention. Beginning during the summer of 1944, numerous surveys were conducted by the 9th Medical Laboratory and by local hospitals and dispensaries. In some instances, the entire personnel of an organization was examined. Infection rates varied from 3 to 33 percent. Rates tended to be higher in units having many cases of diarrhea. The lowest recorded rates may have been due partly to lack of training of laboratory personnel. The highest rate was at the 24th Station Hospital where an epidemic of amebic dysentery among the hospital personnel was traced to a contaminated water supply.
Mostunits had their foodhandlers examined periodically when laboratoryfacilities were providedand found that the elimination of infected personnel from the kitchenswas followed in a number ofinstances by a definite drop in the incidence of diarrhea.
The intensive control measures instituted in the fall of 1944 are reflected more in the lower reported incidence of common diarrhea in the summer of 1945, which was only about one-third of that in 1944, than in the incidence of amebic dysentery which reached a rate of 37 per 1,000 per annum in July 1945 as compared with a rate of 50 per 1,000 per annum in August and September 1944. This lesser decline is to be expected because of the insidious and chronic nature of amebic infection.
In the India-China Division of the Air Transport Command, water supplies in the China stations were unsatisfactory, and coolie labor increased the hazard of contamination. A report by Maj. Clifton W. Bovee, SnC, in July 1945, to the division surgeon, described the deficiencies that still existed and made recommendations for each of the bases. Basic water supply systems or diatomaceous silica filters provided safe drinking water, but water supplied washrooms, showers, and some messes remained highly inacceptable. Additional mechanical equipment and simple distribution systems were required.
Southwest Pacific Area
With theinvasion of individual islands, insanitary conditions were encounteredand contact withnative populations occurred which were conducive to the development ofa high infection rate withE. histolytica.
An illustration of the experience of one division is contained in a report by Maj. Harry J. Bennett, SnC, on a survey made of intestinal parasites in the 37th Infantry Division.17 The division arrived in the Fiji Islands from the United States and New Zealand in June and August 1942. It was transferred to Guadalcanal in April 1943, participated in the New Georgia campaign from
17Report, Maj. Harry J. Bennett,SnC, to ChiefMalariologist, Headquarters, U. S. Army Forces, Far East, 18 Nov. 1944,subject: Intestinal Parasite Survey for the 37th Infantry Division.
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July toSeptember 1943, then returned to Guadalcanal for 1 month, and arrivedin Bougainville inNovember 1943. The first six cases of amebic dysentery were diagnosedon Guadalcanal in May1943. There was no great increase in cases until after the divisionreached Bougainville. Beginningin January 1944, when 17 cases occurred, there was an increase to 67cases in July, a rate of 55 per1,000 per annum. Between 1 November 1943 and 1 November 1944, 460 casesof amebic dysenterywere admitted to hospitals. A stool survey of 1,072 individuals, mostlykitchen personnel from thevarious units of the division, was conducted from July to September1944, and 27.3 percent werefound to harbor E. histolytica. Since only one specimen wasexamined from most individuals, it wasestimated that the actual prevalence was at least 50 percent. Analysisof sanitary conditions underwhich the division had operated suggested that no single source ofinfection could be incriminatedbut that flies, inadequate sanitary facilities, and polluted water allprobably played a part in buildingup a high incidence of infection.
Another illustration is the experience of the 81st Infantry Division which invaded the island of Peleliu, one of the Palau Islands. A high incidence of amebic dysentery led to a preliminary stool survey by Capt. E. C. Nelson, SnC 18 while the division was still on the island. On a single stool examination of 2,210 troops of a regiment, 30 percent were found to harbor E. histolytica; the prevalence in different companies varied from 17 to 44 percent. When the division returned to New Caledonia, the survey was continued with 14,534 (88 percent) of the personnel receiving 1 stool examination. An over-all prevalence of 18.7 percent was found. This study was reported by Murray, Winter, and Sears.19 Captain Nelson investigated the conditions possibly responsible for the high incidence of cases shortly after arrival on the island and concluded that flies were probably the principal source of infection since the water supply was found to be protected from surface contamination and individual food rations were used. The incidence of infection was, in general, highest where the fly population was greatest. One course of specific treatment of all infected personnel reduced the incidence in these individuals to 5.1 percent.
Following the invasion of the Philippine Islands, beginning with Leyte in October 1944, there was an increase in the number of clinical cases of amebiasis through the quarter ending June 1945, after which the number of reported cases declined. This is indicated by the following data from the quarterly reports of the 116th Station Hospital, which was located on Leyte and served the XXIV Corps, the 81st Division, and later the IX Corps and other troops assigned to Base K:
1945 | Cases of amebiasis |
January-March | 330 |
April-June | 761 |
July-September | 215 |
October-November | 72 |
18Essential Technical Medical Data, Headquarters, Pacific Ocean Area,March 1945, inclosure 7.
19 Essential Technical Medical Data, Headquarters,SouthPacific Base Command, March 1945.
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Amebiasiswas considered the most serious disease problem in the Philippine areaexcept forinfectious hepatitis. The increase in the number of new cases ofamebiasis and the rates per thousandper annum for Base K during the first 5 months of 1945 are shown in thefollowing tabulation: 20
Cases | Rates | |
January | 275 | 4.57 |
February | 432 | 7.20 |
March | 822 | 11.37 |
April | 911 | 15.32 |
May | 999 | 16.52 |
In thePhilippines, contact of military personnel with the civilian populationwas greater than in mostof the Pacific islands. In Manila, the destruction of buildings and thegeneral breakdown ofsanitation added to the conditions favorable for the transmission ofamebiasis. The followingmeasures were taken to control amebic dysentery on Base K:
1. All water was treated before consumption by boiling or filtration and then by chlorination. Wells were cased and properly located.
2. Fly control was rigidly enforced by screening and spraying with DDT.
3.Civilians were prohibited from any food handling.
4. The preparation and use of ice was controlled.
5.Messgear was dipped in boiling water before use.
6. Cases and carriers of amebic infection were excluded from food handling.
7.Foodhandlers received stool examinations monthly and were instructed inpersonal sanitation.
8. Temporary kitchen police were instructed in personal sanitation.
9.Military personnel were forbidden to live with civilians.
10. Civilians were not permitted to live within unit areas.
11. Animal pets were discouraged.
12. Consumption of food from civilian sources was forbidden, and green vegetables grown locally were not eaten uncooked.
In the Eighth U. S. Army, which ultimately went from the Philippines to Japan, amebiasis was a relatively unimportant cause for hospitalization at the beginning of 1945 but by June increased to an admission rate of 40 per annum per 1,000 average strength.21 It was believed that a large proportion of the cases resulted from the practice among Army personnel of eating food and drinking untreated water in Filipino homes and restaurants. By means of the issuance of directives and personal visits by medical officers from Army headquarters, an intensive sanitary control program was put into effect in all operational areas. This was followed by a drop in admissions in July to a rate of 9.7 per annum per 1,000, with no later significant increase, and a continued decline after arrival in Japan.
In Hawaii and the mid-Pacific islands, amebiasis was apparently not an important infection.
20Essential Technical Medical Data,Headquarters, U. S. Army Forces, Pacific, July 1945.
21Annual Report, Surgeon, Headquarters,Eighth U. S. Army, Southwest Pacific Area, 1945.
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Middle East Theater
The datain tables 84, 85, 86, and 87 indicate that amebiasis was not soprevalent in this theater asin the China-Burma-India theater and that it reached a peak of 11.33per 1,000 per annum in 1943,after which it declined. A report on amebiasis from the 38th GeneralHospital for the periodNovember 1942 to November 1944 stated that 464 cases of amebiasis hadbeen admitted to thehospital during that period. The highest rates of admission were inApril and May 1943. About one-fourth of these were classed as carriers;the remainder had chronic or acute symptoms. Of thehospital personnel, 816 complained of abdominal symptoms during thisperiod, and 144 (17.8percent) were found to be suffering from symptomatic amebiasis. Purgedstools of foodhandlerswere examined monthly. None was found infected until the hospital hadbeen in that locality forabout a year. Of 77 individuals, 28 (36.4 percent) were found infectedon one of the examinations.Twenty-two of these infected persons were entirely symptom free.22
A report of the Middle East Service Command, 1 June 1944, gave results of a survey of 147 foodhandlers at Camp Russell B. Huckstep. A prevalence of 18.3 percent of infection with E. histolytica was found.
Mediterranean Theater
Amebiasiswas a minor problem in the Mediterranean theater. A report on dysenteryand commondiarrheas by Maj. H. M. Hurevitz, MC, in June 1945, indicated that theadmissions to hospitals andquarters in the entire theater for protozoal dysentery totaled 156cases in 1943 and 851 in 1944.Some of the cases in 1944 were asymptomatic, having been admitted onlybecause E. histolytica had been found in the feces. Surveys ofmilitary personnel had revealed a prevalence in differentunits of only 2 to 11 percent. Many patients with diarrhea or dysenteryin whom E. histolytica wasfound were considered to be suffering from other infections.
The potential menace of diarrhea and dysentery in the forces in North Africa was predicted by Col. Perrin H. Long, consultant in medicine to the surgeon of the Mediterranean theater, in January 1943.23 He made recommendations to the Deputy Surgeon, Allied Force, for sanitary-control procedures, but these were not acted upon at that time. In May, when flies became abundant, bacillary dysentery broke out in American troops in all areas of North Africa. Investigation indicated that the outbreaks were due to bad sanitation in certain units. This led to the publication of a theater circular which dealt with the measures to be employed in the control of dysentery and stressed command responsibility for sanitation.24 Supplies for flyproofing
22Tallant, E. J., and Maisel, A. L.:Amebiasis Among the American Armed Forces in the Middle East. Arch.Int. Med.77: 597-613, June 1946.
23Long, Perrin H.: A Historical Survey ofthe Activities of the Section of Preventive Medicine, Office of theSurgeon,Mediterranean Theater of Operations, United States Army, 3 January 1943to 15 August 1943. [Official record.]
24Circular No. 106, Headquarters, North African Theater of Operations,United States Army, 9 June 1943.
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werereleased from engineer stocks; sanitary inspectors, armed with punitivepowers, visited thebase sections to check up on sanitation; and great efforts were made tobring fly breeding undercontrol. As a result, the admission rates for diarrhea and dysenterywhich had reached 445 per 1,000per annum in June were cut to 213 per 1,000 per annum in July despitethe invasion of Sicily earlyin that month. Measures specifically directed against the transmissionof amebiasis emphasizedprohibition of the. use of raw fruits and vegetables without priorsterilization.
In 1944, with the shifting of the campaign to Italy, control measures against diarrheal diseases were successfully continued. 25
European Theater
Amebiasiswas not a serious problem in the European theater. 26 Thetotal number of admissions forthe years 1942 to 1945 was 1,637, an annual rate, of 0.37 per 1,000average strength. This is brokendown further into an annual rate for 1942 of 0, for 1943 of 0.14, for1944 of 0.36, and for 1945 of0.42 per 1,000 average strength (table 84). Very few cases occurred introops in England; thenumber increased with the invasion of France. This increase appears tohave been partly due toinfections acquired in the Mediterranean theater by troops who invadedSouthern France. Edson,Ingegno, and D'Albora 27 reported 39 casesof amebiasis from a UnitedStates Army general hospitalin North Ireland during a period of 10 months. All patients hadsymptoms and physical signs.Twenty-six were members of one division (presumably the 5th) which wascomposed largely oftroops from the Southern United States who had been through maneuversin Tennessee andLouisiana. The authors suggested that the original infections hadoccurred in the United States andthat some had been acquired subsequently from contact with carriers. Asurvey of 162 foodhandlerswith the 5th Infantry Division revealed 18.5 percent positive for E.histolytica on one stoolexamination. A second survey of a random selection of troops by anotherlaboratory, revealed aprevalence of 19 percent.
A survey of troops from a division in England showed a rate of 16.1 percent for E. histolytica, indicating that the infection was more common than is estimated in the civilian population of the United States. Cases of diarrhea in which E. histolytica was identified were classed as amebic dysentery. It was considered probable that some of these cases were actually cases of bacillary dysentery or common diarrhea and that the actual incidence of active amebic dysentery was less than that reported.
25Annual Report, Surgeon, MediterraneanTheater of Operations, United States Army, 1944, vol. 2.
26Gordon, J. E.: A History of PreventiveMedicine in the European Theater of Operations, U. S. Army, 1941-45,pt. III,sec. 2. [Official record.]
27Edson, J. N., Ingegno, A. P., andD'Albora, J. B.: Amebiasis: A Report of Thirty-nine Cases Observed inan Army General Hospital Stationed in Northern Ireland. Ann. Int.Med. 23:960-968, December 1945.
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PREVENTION AND CONTROL
At therequest of the Chief, Preventive Medicine Service, Office of theSurgeon General, theSubcommittee on Tropical Diseases of the National Research Councilearly in 1941 prepared adirective entitled "Notes on the Treatment and Control of CertainTropical Diseases," which wasissued by the Office of the Surgeon General on 9 June 1941 as CircularLetter No. 56. A revisionof this directive issued on 2 February 1943 as Circular Letter No. 33contained data on theprevention of amebiasis including the necessity for superchlorinationor boiling of water to killcysts, avoidance of raw fruits and vegetables wherever exposed to humanexcreta, exclusion ofinfected persons from food handling, and control of flies andcockroaches.Reference was also madeto AR 40-205 and AR 40-210.Circular Letter No. 33 was superseded by TBMED 159, Amebiasis,issued May 1945, which contained a section on prevention, includingconsiderable detail concerningmess sanitation, foodhandlers, water purification, excreta disposal,and fly control by the use ofDDT.
In general, the measures taken to prevent amebiasis in individual areas of military operation were part of those taken to prevent all forms of gastrointestinal infection.The only additional requirement for the prevention of amebiasis was based upon the fact that a higher concentration of residual chlorine is required to kill the cysts of E. histolytica than to kill bacteria in water. Superchlorination and subsequent dechlorination of water in Lyster bags and canteens was introduced to some extent in 1944 and 1945, but its effect on the incidence of amebiasis cannot be determined. Several directives were issued by theater surgeons 28 describing the disease and its modes of transmission, and methods of diagnosis, treatment, and prevention.
The effective measures of control of amebiasis seem to have been (1) the provision of safe water supplies, (2) the exclusion of native foodhandlers, (3) the examination of military foodhandlers and the exclusion of those found to be infected, (4) the sanitary disposal of human excreta, (5) the prohibition or sterilization of raw fruits and vegetables, (6) the control of flies by screening and DDT spraying, (7) the prohibition of eating in native homes or restaurants, and (8) the enforcement of individual sanitary discipline.
A survey of single, normally passed stool specimens from 4,000 men at the time of separation from military service was made at Fort McPherson, from January to May 1946.29 The specimens were examined by the direct smear and zinc sulfate flotation techniques and doubtful specimens were checked by iron-hematoxylin stain. E. histolytica was identified in 14.3 percent of the specimens. The, prevalence by area of service is shown in table 88.
28 (1) Circular No. 9, Office of the Surgeon, Headquarters, U. S. Army Forces, India-Burma Theater, 2 Apr. 1945, subject: Amebiasis. (2) Technical Memorandum No. 20, Office of the Chief Surgeon, Headquarters, U. S. Army Forces in the Far East, 24 Nov. 1944, subject: Amebiasis: Amoebic Dysentery.
29Survey of Intestinal Parasites in Soldiers Being SeparatedfromService. Bull. U. S. Army M.Dept. 6: 259-262, September 1946.
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Theresults of this survey coincide in general with the clinical andlaboratory experience in overseastheaters and indicate that many infections acquired overseas wereintroduced into this country. 30
RESEARCH ON WATER PURIFICATION
Theimportance of water as a vehicle for the transmission of E.histolytica was emphasized by theepidemic of amebiasis in Chicago in 1933. Although some work was donebefore World War II onthe effectiveness of chlorine in killing the cysts of E. histolytica,Chang and Fair 31 in 1941 werethe first to demonstrate the degree to which cysts were resistant tochlorination under variousconditions of water quality. Their work was confirmed by Brady, Jones,and Newton 32 in 1943.Later studies by Fair 33 demonstrated that,if calciumhypochlorite solution were used in Lyster bags,a residual chlorine of 7.5 parts per million would be required at atemperature of 10 0C. with a 30-minutecontact to assurethe killing of cysts. Under these conditions, other chlorine demands ofthewater would probably raise the initial chlorine demand to 25 to 30parts per million; acidificationwould also be necessary to ensure a desirable pH value of the water,and, in order to produce apalatable water, dechlorination by sodium sulfite in the receivingvessel would be necessary. Theuse of halazone (p-dichlorosulfamidobenzoic acid) tablet's presented aneven greaterproblem because of their slow dissolving time and the moreobjectionable taste which they conveyto water. These difficulties reduced the practicability of employingchlorine compounds to disinfectwater in canteen quantities, although
30An estimate of the prevalence ofamebiasis among veterans of World War II may be obtained from recordsof veteranshospitals showing the number of cases discharged from the hospitalssince the war. It was reported at a meeting ofRegional Consultants on Tropical Medicine, Veterans' Administration,held at Savannah, Ga., on 5 November 1950, thatduring the years 1945-48, a total of 3,673 patients treated foramebiasis were discharged. There was a rapid increase inthe number of cases diagnosed after the return of troops from overseas,and the increase was continuous through 1949.
31See footnote 13, p. 486.
32Brady, F. J., Jones, M. F., and Newton,W. L.: Effect of Chlorination of Water on Viability of Cysts of Endamoebahistolytica.War Med. 3: 409-419, April 1943.
33Fair, (I. M.: Interim Report No.4;Disinfection of Water; Contract OEMemr-251. NRC Bull. Sanit. Eng. Div.12 July1945, pp. 195-219.
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provisionfor hyperchlorination and dechlorination was made in some areas ofmilitary operation.
For these reasons, Fair and his associates investigated other halogens and found that iodine was a more useful cysticidal agent. The first iodine tablet developed contained Bursoline, a mechanical mixture in the proportion of 2 moles of diglycine hydriodide to 1 mole of elemental iodine. On solution in water, tablets containing this mixture liberated free iodine. This element has the advantages over chlorine of not being so easily hydrolyzed and not reacting with ammonia or organic nitrogenous substances to form iodoamines.34 For field disinfections it was found that, with a contact time of 10 minutes, 4 parts per million of free iodine were required to kill 60 cysts per ml. at 23 ? Centigrade. A dose of 7.5 to 8 parts per million was considered sufficient to take care of the great majority of waters and leave sufficient residual for disinfecting action in 10 minutes, unless the water was very cold. Tablets containing Bursoline, disodium dihydrogen pryo-phosphate as an acid-buffering agent, and filler were prepared for use in canteens, and field tests showed that they were satisfactory because of their stability, rapid solution, and the lack of disagreeable taste of the treated water. There was also no evidence that iodine, in the dosage employed, would be harmful to consumers. Bursoline tablets were, therefore, produced on a small commercial scale and were used to some extent in the India-Burma and Pacific theaters late in the war.
Furtherinvestigation by Fair and his associates indicated that Globaline(crystalline tetraglycinehydroperiodide) could replace the Bursoline mixture and therebv reducethe amount of inactiveiodine added to the water. Buffered tablets of this compound, whichwould liberate 8 mg. of iodineper tablet, were found to be stable under normal conditions of storageand use. They dissolved inless than a minute and disinfected most waters in 10 minutes with theuse of one tablet per canteen.Two tablets were required for highly colored waters and 20 minutes fordisinfection of very coldwater. High turbidity, alkalinity, ammonia, urea, and salt had noappreciable effect on thedisinfecting efficiency. Field tests in the armed services showed greatsuperiority of Globaline overchlorine compounds because of palatability, rapidity of disinfection,and convenience.
Synthetic detergents were tested for cysticidal activity under contract with the Office of Scientific Research and Development by Fair, Chang, Taylor, and Wineman 35 and by Kessel and Moore.36 A number of cationic compounds were found to be effective.Fair reported that Ceepryn (1-n-hexadecyl pyridinium chloride) and Fixanol (cetyl pyridinium bromide) were cysticidal in water at concentrations of 25 to 50 parts per million, but that it was not practical to
34 Fair, G. M.: Water Disinfection andAllied Subjects. In United States Office of ScientificResearch and Development:Advances in Military Medicine. Boston: Little and Brown Co., 1948, vol.11, pp. 520-531.
35Fair, G. n1., Chang, S. L., Taylor, M.P., and Wineman, M. A.: Destruction of Water-Borne Cysts of Endamoehahistolytica by Synthetic Detergents. Am. J. Pub. Health 35:228-232,March 1945.
36Kessel, J. F., and Moore, F. J.:Emergency Sterilization of Drinking Water With Heteropolar CationicAntiseptics.Am. J. Trop. Med. 26: 345-350, March 1946.
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use themin the Armed Forces because at that concentration they foam badly andhave a bitter taste.
Theeffectiveness of ozone as a cysticidal agent was investigated duringthe war by Kessel and hiscoworkers,37 and more recently by Newton andJones.38 In laboratorytests they found ozone moreactive than chlorine and not influenced by hydrogen ion concentrationor organic matter, butdifficulty of production and rapid dissipation in water, leaving noresidual, made it unsuitable forpractical application.
Ultraviolet light as a cysticidal agent was also tested on a small scale during the war by Stoll, Ward, and Mathieson at the Naval Medical Research Institute.39Although it was found to be effective under experimental conditions, it did not appear to be a practical agent for the purification of military water supplies.
The efficiency of the portable sand filters of the Army for the removal of cysts of E. histolytica from water was investigated by the Corps of Engineers during the war in cooperation with the National Institutes of Health.40 It was found that when these filters were operated at the rate for which they were designed they allowed some cysts to pass through. This danger was increased by the tendency to operate the filters at a higher rate when a larger quantity of water was required. Diatomaceous earth was found to be efficient in removing all cysts, irrespective of the nature of the water, at flow rates as high as 7 gallons per square foot per minute. Portable filters of this type were manufactured and were used to a small extent during the latter part of the war in the China section of the Air Transport Command.
RESEARCH ON SEWAGE TREATMENT
Cram41studied the survival of cysts of E. histolytica underexperimental conditions simulatingsewage treatment processes in common use. The cysts were not removed byprimary settling, butpassed out in the effluent, and also passed through trickling filtersand survived activated sludgetreatment. They were removed by alum floc precipitation duringsecondary settling, and also byintermittent sand filtration. They did not survive sludge digestion.These results indicated thateffluents from sewage disposal plants would be likely to contain cystsof E. histolytica which mightbe transported for long distances in streams.
37Kessel, J. F., Allison, D. K., Kaime,M., Quiros, M., and Gloeckner, A.: The Cysticidal Effects of Chlorineand ozoneon Cysts of Endamoeba histolytica, Together With a ComparativeStudy of Several Encystment Media. Am. J. Trop.Med. 24: 177-183, May 1944.
38Newton, W. L., and Jones, M. F.: TheEffect of Ozone in Water on Cysts of Endamoeba histolytica. Am.J. Trop.Med. 29: 669-681, September 1949.
39Naval Medical Research Institute,ResearchProject X-110, Report 5, 2 Feb. 1945, subject: The Effect ofUltravioletRadiation on Cysts of Endamoebahistolytica.
40(1) Black, H. H.: Army Field WaterSupply Developments.Am. J. Pub. Health 34:697-710, July 1944. (2)EngineerBoard, Corps of Engineers, Report 834, 3 July 1944, subject: Efficiencyof Standard Army Water Purification Equip mentand of Diatomite Filters in Removing Cysts of Endamoeba histolyticafrom Water (3)Newton, W. L.: Water
TreatmentMeasures in Control of Amebiasis. Am. J. Trop. Med. 30:135-138, March1950.
41Cram, E. B.: The Effect of VariousTreatment Processes on the Survival of Helminth Ova and Protozoan CystsinSewage. Sewage Works J. 15:1119-1138, November 1943.
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RECOMMENDATIONS
If theexperience gained in World War II is to be utilized in the preventionof amebiasis and otherintestinal infections in future military operations, it is necessary tomake preparations in advanceand to educate each new generation of physicians in the part it mustplay in a preventive program.The following recommendations are suggested
1. Sanitary discipline of camps, messes, and combat units is a responsibility of the commanding officer and should be given equal importance with other phases of military training. Instruction and practical experience should be given to all personnel from highest to lowest rank. This must include specific directives, and the participation of medical and sanitary officers well trained in the details of preventive measures.
2.Continuous adequate training should be provided for medical, sanitaryand laboratory personnelin the accurate diagnosis, treatment, and prevention of amebiasis,considering it as a specificinfection of equal importance to bacillary dysentery and otherintestinal infections.
3. Efficient portable and emergency water supply equipment and supplies should be devised and prepared which can be furnished to overseas forces and combat units as soon as they are activated.
4.Efficient equipment for mass sanitation, excreta disposal, and flycontrol should be provided andgiven high priority in supplies accompanying overseas forces.
5. Special instruction in personal sanitation and continuous supervision of all foodhandlers in military units should be required.
6. Onthe occurrence of any epidemic of diarrhea in troop units, stoolsshould be examinedparticularly for E. histolytica as one of the causative agents.If it is found, examination of stoolsfrom all members of the unit and treatment of all infected individualsshould be carried out. Searchshould be made for the source of infection and appropriate preventivemeasures should be instituted.
7. Special stool examinations for E. histolytica on all troops returning from overseas or on discharge from military service should be performed whenever practicable and those found to be infected, should be treated.
