CHAPTER V
Helminthiasis
Harry Most, M.D.
Helminthic infections1 wereacquired by a relatively large number of military personnel during World War II.The parasites discussed in this section may be classified as follows: (1) Thosethat enter the body as larvae via the skin or mucous membrane (hookworm and Strongyloidesstercoralis) and (2) those that enter the body via the gastrointestinaltract (Ascaris lumbricoides, Trichuris trichiura, Trichinella spiralis,Enterobius vermicularis, and tapeworms).
Particularly in the Pacific islands, every possible conditionexisted to facilitate the dissemination of intestinal parasites. Infection innative and enemy troop populations was high, troops frequently operated interrain containing human feces; facilities for fecal disposal were limited ornonexistent; and facilities for washing hands, bodies, clothing, and messequipment were either limited or absent.
Table 21, compiled from data from seven surveys,2shows the high incidence of parasitism in the various groups of natives andprisoners in areas where the U.S. Army operated under military conditions. Theunsanitary living conditions made the acquisition of many of the parasiticinfections almost inevitable.
Table 22, which represents the results of surveys doneoverseas and in the United States,3 shows theextent of infections in troops in the United States. The incidence was at leasttwice as great in troops who served in the Pacific as in those who served in thecontinental United States only; in general, probably, the incidence of infectionoverseas was actually greater than is indicated in the table. Examinations ofsingle specimens of stool by direct smear only were frequent. Troops surveyedafter returning to the United States may previously have had courses oftreatment. Higher percentages were discovered in small groups who were nottreated previously and in those in whom several stools were examined byconcentration techniques.
1Schistosomiasis and filariasis which are discussed in chapters 3 and 4, respectively, are excluded from the discussion in this chapter.
2The various sources from which the data were compiled are listed in table 21.
3The various sources from which the data were compiled are listed in table 22.
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TABLE 21.-Prevalenceof parasitism in various groups of natives and prisoners, in tropical areas
HOOKWORM INFECTIONS
Incidence
The incidence of hookworm infections varied in differentareas and frequently was related to the branch of service (being highest in theinfantry) and to the duration of combat or to the length of residence in thearea. A total of 800 cases were discovered among 2,000 Australian troops who hadbeen in combat in New Guinea for periods of several weeks to months; 97 percentof one brigade was infected. In American troops serving in the Pacific, theprevalence was from 10 to 15 percent, according to several large surveys. Aftercampaigns in the Solomon and Philippine Islands, as many as 20 to 40 percentinfected might be found among those surveyed.
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Area of service and of survey | Number of troops examined | Percent parasites recovered | |||||
Hookworm | Strongyloides stercoralis | Trichuris trichiura | Ascaris lumbricoides | Entamoeba histolytica | Schistosoma japonicum | ||
(1) Solomon Islands | 1,000 | 23.6 | --- | --- | --- | --- | --- |
(2) South Pacific | 4,624 | 5.2 | --- | --- | --- | 18.7 | --- |
(3) South Pacific | 2,300 | 10.4 | 0.9 | 1.7 | 0.8 | 5.8 | --- |
(4) Manila | 630 | 14.1 | .3 | 10.7 | 17.8 | 8.1 | --- |
(5) Leyte | 206 | 39.8 | --- | --- | 34.4 | 15.0 | 9.2 |
(6) Leyte1 | 463 | 16.4 | 2.2 | 11.4 | 3.2 | 3.5 | --- |
(6) Pacific1 | 1,261 | 10.8 | 1.0 | 3.3 | 1.3 | 1.0 | --- |
(6) European and Mediterranean1 | 535 | 5.0 | .2 | 1.3 | .7 | .4 | --- |
(7) Pacific1 | 342 | 10.2 | --- | --- | --- | 11.7 | --- |
(7) European1 | 310 | 12.9 | --- | --- | --- | 13.8 | --- |
(7) United States2 | 398 | 6.8 | --- | --- | --- | 7.0 | --- |
(8) Pacific1 | 2,500 | 11.5 | --- | --- | --- | --- | --- |
(8) United States2 | 4,300 | 6.2 | --- | --- | --- | --- | --- |
1Area of service; the survey was conducted in theUnited States.
2Service in continental United States only.
NOTE.-Figures in parentheses identify sourceof data.
Source:
(1) Essential Technical Medical Data, U.S. Army Forces, SouthPacific Area, for February 1944, dated 7 Mar. 1944.
(2) Essential Technical Medical Data, South Pacific BaseCommand, for March 1945, dated 15 Apr. 1945.
(3) Essential Technical Medical Data, South Pacific BaseCommand, for April 1945, dated 15 May 1945.
(4) Essential Technical Medical Data, U.S. Army Forces,Pacific, for October 1945.
(5) Medical Bulletin No. 19, Office of the Surgeon,Headquarters, Army Service Command I, Okinawa, 17 Sept. 1945.
(6) Hesselbrock, W. B., Lippincott, S. W., and Palmer, E. D.:Large-Scale Routine Examinations of Stool for Parasites; Practical Experience ina General Hospital in the Zone of Interior. Am. J. Clin. Path. 16: 264-269,April 1946.
(7) Report, Fourth Service Command Laboratory, 3 Mar. 1946.
(8) Most, H., Hayman, J. M., Jr., and Wilson, T. B.: HookwormInfections in Troops Returning From the Pacific. Am. J.M. Sc. 212: 347-350,September 1946.
Some infections disappeared spontaneously with the passage oftime and many were eradicated by repeated courses of treatment, reducing thefigure to about 10 percent by the time surveys were conducted in the UnitedStates.
Only about 5 percent of the troops who served in the Europeanand Mediterranean theaters had hookworm. This was similar to the findings in menwho served in the United States only, with the exception of one survey4which was conducted at a separation center in the southern part of the UnitedStates, where the incidence of infection was notably higher (12.9 percent ofthose examined). Sanitary and combat conditions in the European andMediterranean areas were often favorable to the acquisition of parasites. Thatinfection did not occur more frequently may have been
4Report, Fourth Service Command Laboratory, 3 Mar. 1946.
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due to low native and enemy troop infection in those areas,to particular combat conditions, or to insufficient time or temperatures fordevelopment of infecting larvae. Generally speaking, the infections discoveredin men returning from the European and Mediterranean theaters were regarded ashaving been acquired in the United States before military service, although somemay have been the result of local conditions overseas.
Hookworm infection in troops who saw no oversea duty wasabout 5 percent and was a reflection of the existence of hookworm in varioussouthern States. A small number of infections due to Necator americanus mayhave been acquired during maneuvers in hookworm areas in the United States.
Nature and Severity of Infections
Few attempts were made overseas to recover adult hookworms aftertreatment, and few egg counts were done. At the 39th General Hospital, Auckland,New Zealand,5 stool egg counts in 39patients varied from 350 to 71,000 per gram of feces, the majority being between1,000 and 5,000. A total of 602 worms, all Ancylostoma duodenale, wererecovered from 11 patients, 411 of the worms from the patient having the 71,000stool count. The same parasite was recovered from 3 patients treated at the 8thGeneral Hospital, Dumbea Valley, New Caledonia,6and from 8 of 14 patients reported from India.7The series from India included also two patients with Necator parasitesand four with both varieties. The number of worms in the 14 cases in Indiavaried from 8 to 100. These scattered figures indicate that Ancylostoma wasresponsible for a considerable number of mild infections.
Further studies in the United States have confirmed thisimpression. In one general hospital,8 outof 169 patients from whom adult worms were recovered after treatment, 87 had Ancylostoma,69 had Necator, and 13 had both. The majority of hookworm infectionsacquired overseas were Ancylostoma, although a few men from northernnonhookworm areas picked up Necator (which is the variety endemic insouthern United States), and some already infected with Necator acquired Ancylostomaas well.
On the whole, hookworm infections were not heavy. The numberof worms recovered per patient in all but 14 of the 169 patients just mentionedwas 25 or less. The maximum number of Necator was 86 and of Ancylostoma,112. The average stool count for Necator infections was 1,900 (range100 to 9,100) and for Ancylostoma, 2,295 (range 200 to 9,800). All
5Essential Technical Medical Data, U.S. ArmyForces, South Pacific Area, for June 1944, dated 5 July 1944.
6Essential Technical Medical Data, South Pacific BaseCommand, for April 1945, dated 15 May 1945.
7Essential Technical Medical Data, U.S. Army Forces,India-Burma Theater, for June 1945, dated 1 Aug. 1945. Enclosure 4 thereto.
8Most, H., Hayman, J. M., Jr., and Wilson, T. B.: HookwormInfections in Troops Returning From the Pacific. Am. J. M. Sc. 212: 347-350,September 1946.
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169 patients had had previous courses of treatment, but inanother group not previously treated the average stool counts for Necator andAncylostoma were 2,400 and 3,200, respectively. It is pertinent to recallhere that A. duodenale lays almost twice as many eggs a day as N.americanus. Stool counts of the same order of magnitude have been reportedin other series.
Whether Ancylostoma will become established in theUnited States, time will tell.9 Persisting infections will,presumably, be extremely light. An attempt was made to survey troops overseasand to treat the positives before they left. The pressure of demobilization,however, was so great that it was impossible to carry out this program.
Effect of Infection on the Host
As a rule, several hundred hookworms are necessary to producesymptoms. Since less than 25 worms were present in 90 percent of Army cases, itis not surprising that hookworm disease was a very uncommon manifestation ofhookworm infection. Anemia was infrequent and usually mild, but leukocytosis andeosinophilia were common. Numerous courses of treatment were often required toeliminate all worms, resulting in prolonged hospitalization of patients. Inoccasional cases, clinical symptoms were disabling, and the basis for acute orchronic vague complaints was obscure until hookworm infection was discovered.These factors are discussed briefly.
Anemia.-Severe anemia did not occur in U.S. troops, andmuch of the mild anemia observed may have been due to tropical and militaryconditions rather than to hookworm infection. In one report,10 15percent of 907 men without hookworm had erythrocyte counts below 4 million and37 percent had a hemoglobin of less than 80 percent. Only 20 percent of 93 menwith hookworm had erythrocyte counts below 4 million and 34 percent hadhemoglobins less than 80 percent. The difference in the two groups is notsignificant. In one study11 of 74 patients with hookworm, 48 of whom hadgastrointestinal symptoms, only 3 had anemia (hemoglobin 11 to 13 gm.). Inanother series,123 of 39 patients had anemia (red blood cells 2.9 to3.8 million, hemoglobin 56 to 76 percent). In a general hospital in the UnitedStates, among 100 men who had hookworm as an incidental finding,13 therewas none with anemia attributed to this infection.
White blood cells.-Leukocytosis and eosinophilia commonly occurred early in the course of hookworm infection. The persistence of the latter for many months was used in estimating the probable rate of hookworm infec-
9Up to 1953, no case of this parasite acquired in the United States has been reported.
10Essential Technical Medical Data, U.S. Army Forces, South Pacific Area, dated 1 Feb. 1944.
11Hodes, P. J., and Keefer, G. P.: Hookworm Disease; A Small Intestinal Study. Am. J. Roentgenol. 54: 728-742, December 1945.
12See footnote 5, p. 148.
13See footnote 8, p. 148.
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tion in the 43d Infantry Division.14 When comparedto positive stool counts, however, eosinophilia did not prove to be a veryreliable criterion. Examination of one or two stools by brine flotation injudiciously sampled, representative small groups is a more satisfactory method.Eosinophilia occurred most frequently in infantry combat outfits and wasdirectly related to the duration of combat or to the length of residence in theendemic area. The peak occurred 3 or 4 months after the greatest exposure andfell in a little over 8 weeks' observation. The highest eosinophilia observedwas 68 percent and the greatest leukocytosis, 28,000. Eosinophilia, ranging from10 to 70 percent, was found in other groups of patients with hookworm in India.15An average eosinophilia of 10.2 percent in a group of 100 men in the United States,16 with hookworm as the only parasitic infection, attests to thepersistence of this sign.
Clinical findings.-Hookworm disease was evident in only 5of a series of 600 patients with hookworm infection.17 However, various clinicalsigns and symptoms were observed that were attributed to the infection. InIndia,abdominal pain and tenderness, nausea, vomiting and diarrhea, and eosinophiliain some patients were not explained until hookworm eggs were found in thestools. In 50 selected cases of apparently recent hookworm infection,18the onset of symptoms was often acute, simulating gastroenteritis. The signs andsymptoms noted in this group are as follows:
| Signs and symptoms: |
| Incidence |
Diffuse abdominal pain, after meals and during the night | percent | 86 |
"Foxhole" cough without coryza or sore throat, appearing 1 to 2 weeks after ground itch and lasting 3 weeks | percent | 70 |
Abdominal tenderness | percent | 66 |
Diarrhea (average 6 stools per 24 hours) without blood or pus | percent | 52 |
Ground itch 4 to 6 weeks before onset of abdominal symptoms | percent | 28 |
Anorexia and weight loss | Common | |
Low grade fever | Occasional | |
The leukocytes numbered as many as 41,000 per milliliter,averaging 13,700 per milliliter. The maximum percentage of eosinophiles was 70percent, averaging 34 percent. Eggs were found in a single direct smearexamination of the stools in 21 percent and in 57 percent after repeatedexaminations. When concentration methods were used, 86 percent of firstexaminations were positive, and all were positive with three examinations. From8 to 100 adult worms per patient were collected from 14 cases.
Treatment completely relieved 20 percent of the 50 patientsof symptoms, improved 55 percent, and produced no change in 25 percent. Stoolswere positive after two courses of treatment in 63 percent of the men.
14Liebow, A. A., and Hannum, C. A.: Eosinophilia, Ancylostomiasis, and Strongyloidosis in the South Pacific Area. Yale J. Biol. & Med. 18: 381-403, May 1946.
15See footnotes 7, p. 148; 10, p. 149; and 11, p.149.
16See footnote 8, p. 148.
17See footnote 14.
18See footnote 7, p. 148.
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Complete gastrointestinal studies were conducted in a generalhospital in Burma19 on 74 patients whose symptoms appeared several weeks aftertheir arrival in that country. Of the 74 patients, 48 were hospitalized becauseof abdominal symptoms and the rest, for other reasons. The majority of the 48patients complained of dull, cramping, or gnawing intermittent abdominal pain,most marked in the epigastrium or the midabdomen. In some patients, the onsetwas acute, marked by nausea, vomiting, pain and diarrhea, and occasionally feverwith a temperature of about 100? F. Anorexia and bloating were common. Theclinical diagnosis at onset was frequently peptic ulcer. Change from fieldrations to bland hospital diet brought no relief. In 54 acute cases,eosinophilia was between 10 and 70 percent, half being over 30 percent. Theerythrocyte count and hemoglobin values were normal in all but three patients.
Roentgenographic studies.-Roentgenographically, theintestines of the 54 patients showed the following:
Distal duodenum.-No disturbance in tone or rugalpattern in mild infections. Moderate to marked thickening and prominence ofmucous membrane in 26 patients. Irritability. Tenderness on palpation frequent.
Jejunum.-Tenderness on palpation in most cases. Rugalabnormalities, from slight prominence of the valvulae conniventes to severecoarsening of the mucosal folds in 60 percent of patients. Serrations betweenfolds and height and contour of rugae variable. Normal intestinal tone in halfthe patients; increased tone in half, with narrowing of lumen and shortening ofloops. Irritability.
Ileum.-Rugal prominence in contour similar to ileum but toa lesser degree. Normal mobility in majority; delayed mobility in 30 percent.Normal tone in half the patients; increased tone in half, producing bolusformation and segmentation.
These changes, which are those of a disordered motorfunction, appeared first in the proximal jejunum, then in the distal duodenumand distal jejunum, and finally in the entire ileum in severe cases. It wassuggested that they resulted from disturbance in the intramural nervousmechanism of the myenteric and submucosal plexuses. Edema and cellular changesin the wall of the intestine associated with the presence of adult hookwormswere of secondary importance. In a fatal case of scrub typhus, 260 Ancylostomawere found in the small intestine. Small erosions of the mucosa, edema,ecchymosis, and occasional worms in the submucosa were observed. After one ormore courses of treatment, improvement was manifested by loss of tenderness topalpation, loss of hypermotility and irritability, and restoration of normaltone. Recovery was complete in mild cases within a few weeks after treatment,but X-ray changes sometimes persisted for months.
19See footnote 11, p. 149.
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Treatment
It was a disappointment to find that tetrachloroethylene wasfrequently unsuccessful in eliminating all hookworms. In one oversea hospital,20only 46 percent were cured after a course of 4.0 ml. tetrachloroethylene, 74percent after three courses, and one patient required seven courses beforestools became negative. In a series of 50 in India,21 63 percent ofthe men had positive stools after two courses, while in another oversea area22only 50 percent of 600 men were reported free of infection after 1 to 14courses.
The unexpected failure of tetrachloroethylene was shown23 tobe due to the relative refractoriness of Ancylostoma to the drug ascompared to Necator. Stools were examined from patients with untreatedhookworm before, and a week after, treatment, and the results correlated withthe species of adult recovered. Only 25 percent of 35 patients with proved Ancylostomainfections were cured after one course of 4.0 ml. tetrachloroethylene, and55 percent after two courses. This contrasts with 66 percent of 24 patients withNecator cured after one course of treatment and 85 percent after twocourses. Since Ancylostoma accounted for three-fourths of hookwormacquired overseas, the resistance of this species explains the poor resultsobtained. Drug deterioration in the Tropics was not responsible since use offresh drugs in the United States gave no better results. Of 100 men previouslytreated overseas, 42 percent were cured by one course of treatment in the UnitedStates, 79 percent were cured after three treatments, and 98 percent after sixtreatments. It is probable that Necator infections were largelyeliminated by prior treatment and failures were due to the persistence of Ancylostoma.Increase of dosage of tetrachloroethylene to 5.0 ml. did not improve itsefficacy.
No striking toxicity was observed after from 3.0 to 5.0 ml.doses in thousands of men. A combination of tetrachloroethylene and oil ofchenopodium was not thoroughly tested. Hexylresorcinol apparently was relativelyineffective in eliminating hookworm infections, but no detailed studies wereconducted.
Military Aspects of Hookworm Infections
Since the vast majority of hookworm infections were light,producing no anemia or symptoms, the military efficiency of U.S. troops was notimpaired by such infections. Severe infections resulted in hospitalization of asmall number of men, but for the most part hookworm infections were discoveredincidentally in the course of surveys or hospitalization for other causes.
20See footnote 5, p. 148.
21See footnote 7, p. 148.
22See footnote 14, p. 150.
23See footnote 8, p. 148.
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Failure of treatment often resulted in needlessly prolongedhospitalization of men who were clinically well but still had hookworm eggs inthe stools or prolonged eosinophilia. At Fort Bragg, N.C., for example, 61patients, in whom hookworm was discovered incidentally, lost an average of 14.4days per man (longest 48 days) because of repeated courses of treatment.24 Itwas recommended from that station that 2 days on quarters' status wassufficient for treatment. A similar recommendation to minimize time lost fromduty was made by an antiaircraft medical officer.25 Because mostinfections were subclinical and because Ancylostoma was often noteliminated by tetrachloroethylene, it was officially recommended in 194526 thattreatment be limited to two courses.
OTHER PARASITIC INFECTIONS
Ascariasis
Infections due to Ascaris lumbricoides did notconstitute a clinical or military problem. Ascariasis was discovered inrelatively few troops (1 to 3 percent) after their return from overseas. Thisis probably due to the short lifespan of this parasite and to the fact thathexylresorcinol, which is fairly effective against Ascaris, wasfrequently used in treating hookworm infections. However, Ascaris infectionwas rather prevalent in certain Pacific areas in which the local incidence wasvery high. It was found in 18 percent of 630 American troops in the vicinity ofManila and in 34.4 percent of 206 men in an engineer group on Leyte. Infectionswere not symptomatic and were easily eliminated with hexylresorcinol.27 Prolongedhospitalization was rare.
Strongyloidiasis
The incidence of strongyloidiasis in troops from the Pacificwas from 1 to 3 percent. Strongyloides stercoralis were often found inpatients who had hookworm. In 633 stools that were positive for hookworm or Strongyloides or both, 7.4 percent hadStrongyloides.28 Noreports of significant clinical symptoms caused by S. stercoralis areavailable, although severe diarrhea has been observed. Eosinophilia was common.No cases of chronic
24Williams, A. F., and Kinsman, J. M.: Management of Subclinical Hookworm Infestation in the Army. [Professional paper.]
25Report, G. H. Houck, P. L. Burlingame, M. S. M. Watts,and J. I. Marcones, 4th AA Command, San Francisco, Calif., 5 Aug. 1945, subject:Report of Disinfestation Program in 762d and 891st AAA Gun Battalions.
26The Management of Hookworm Infection. Bull. U.S. Army M.Dept. 4: 660-661, December 1945.
27Studies subsequent to the close of hostilities have shown thetherapeutic value of piperazine hexahydrate (Antepar) in ascariasis. Withdaily administration of 50 to 75 mg. per kilogram for 5 days, the cure rate has been well above that observed following a single course of hexylresorcinol. Piperazine is also the drug of choice in treating pinworminfections.
28See footnote 14, p. 150.
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infection or of pulmonary involvement have been reported.Discovery of this parasite in the stools or in material drained from theduodenum occasionally accounted for the existence of prolonged eosinophilia.Frequent failure of standard treatment with gentian violet medicinal (96tablets, 0.03 gm. during 16 days) led to prolonged hospitalization. Intensivetreatment via duodenal tube or gradual increase in daily dosage to the maximumtolerance (18 tablets daily) produced cures in one hospital. Differentialdiagnosis of strongyloidiasis and schistosomiasis japonica could often befacilitated by examination of liquid postcathartic stools or duodenal fluid.29
Trichuriasis
The incidence of trichuriasis in men from the Pacific wasfrom 10 to 15 percent and closely paralleled the incidence of hookworm. Trichuristrichiura produced no symptoms or signs other than slight eosinophilia.One case of epileptiform convulsions, probably due to sensitivity to the proteinof the adult worm, was observed by the author. Large amounts of anticonvulsantdrugs were required for control, but after the elimination of worms with twocourses of leche de higuer?n, convulsions ceased and did not return whenanticonvulsants were omitted. Examination of stools for T. trichiura frequentlyled to discovery of other potentially more severe infections (Entamoebahistolytica). Common anthelmintics were not effective in eliminatingwhipworms, but, since these parasites were of no clinical significance,treatment was not attempted and hence prolongation of hospitalization did notensue.
Creeping Eruption
A total of 19 cases of cutaneous infection with Ancylostomabraziliense larvae were reported from Camp Rucker, Ala., over a period of2? years.30 The average time lost from duty was 27 days; themaximum, 77 days. Local freezing with ethyl chloride spray controlled theinfection. Associated eosinophilia and pulmonary infiltration have beenreported. The infrequency of this infection is somewhat surprising in view ofthe probability of exposure to terrain soiled by cat and dog feces.
Tapeworm
For the years for which this information is available, a total of 14 cases of infections due to larvae of Taenia solium (cysticercosis) or Echino-
29Baroody, B. J., and Most, H.: The Relative Efficiency of Water Centrifugal Sedimentation and Other Methods of Stool Examination for Diagnosis of Schistosomiasis Japonica. J. Lab. & Clin. Med. 31: 815-823, July 1946.
30Annual Report, Camp Rucker, Ala., for 1944, dated 13 Jan. 1945.
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coccus granulosus (hydatid disease) were reported in military personnel.31
A small number of cases of dwarf tapeworm infections (Hymenolepis nana) were discovered incidentally to routine stool examination. Their origin may or may not have antedated military service. There were no clinical manifestations, and the infection was readily eliminated by several courses of oleoresin of aspidium. Dwarf tapeworms were present in some men who were on prolonged quinacrine suppression. This drug has been said to inhibit the development of a related parasite (Hymenolepis fraterna) in the mouse. Beef tapeworms (Taenia saginata) were very rarely found, possibly because of the use of federally inspected meat and, overseas, of large amounts of processed beef.
Trichinosis
During World War II, a total of 285 admissions fortrichinosis were reported in the U.S. Army. Of this total, 77 occurred outsidethe continental United States, giving an average rate of 0.01 per 1,000 averagestrength per year; the 208 admissions reported in the continental United Statesproduced the same rate.
In May 1941, before the United States had entered World WarII, a small outbreak of trichinosis occurred at Camp Edwards, Mass.,32 resultingin the hospitalization of 13 acutely ill soldiers. Diagnosis was proved in fourcases by muscle biopsy. These patients were hospitalized for from 31 to 33 days.Skin tests were positive in 28 percent of the other 129 members of the samecompany who ate in the same mess. Thirty percent of these men also hadeosinophilia above 10 percent, indicating that subclinical trichinosis may havebeen present in 25 percent of the company.
SUMMARY
Parasitic infections occurred fairly extensively in World WarII. This was principally due to operations in the Pacific islands where, with ahigh incidence among natives and enemy troops, living conditions and type ofmilitary operations presented a perfect background for infection.
Hookworm was the most common of the pathogenic helminths. InU.S. troops returning from the Pacific, the incidence of hookworm was at leasttwice that found in men who had served only in the United States or in Europe. Ancylostomaduodenale was responsible for the majority of infections. Infection wasgenerally light, and hookworm disease was rare.
31According to sample tabulations of individual medicalrecords, there were 13 admissions for echinococcus infection during 1942-45reported among U.S. Army personnel, and 1 admission for cysticercosis in 1944 (none in 1945; data not available for 1942-43). Dataon secondary cases, available only for the years 1944 and 1945, showed no cases for these diseases during the2 years. All but one of the echinococcosis cases were admitted in the Zone of Interior; one in Hawaii. Thecysticercosis case was admitted in the Mediterranean theater.
32Marble, A., Skoog, A. P., and Bucholz, D. J.: Trichinosis: Report of an Outbreak at Camp Edwards, Massachusetts. Mil. Surgeon90: 636-643, 1942.
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Tetrachloroethylene was not very effective in treatinghookworm, particularly A. duodenale. Prolonged hospitalization of menwithout clinical symptoms, because of persistence of eggs in the stools,resulted in many days lost from duty. Military efficiency of U.S. troops was notimpaired, but it is conceivable that a prolonged war in severely infected areasmight result in heavy Ancylostoma infections of a more serious type.
Other common intestinal parasites were also prevalent, butthese did not constitute an important medical or military problem.
Clothing and skin protection against larvae of hookworm or ofStrongyloides, possible soil treatment for destruction of larvae oreggs, and development of more effective drugs for the treatment of Ancylostoma,Trichuris, and Strongyloides, remain to be achieved.
