Communicable Diseases, Table of Contents
CHAPTER XIX
INTESTINAL PARASITES
The greater number of the different kinds of animalintestinal parasites are of little or no military significance; they may haveslight if any apparent effect upon either the health or efficiency of theirhosts; they may be so restricted in occurrence as to be of little quantitativeimportance in the total volume of disease and physical deficiency of the troops.However, in the cases of seemingly healthy carriers of intestinal parasites, themilitary significance of the diseases which they cause rises in proportion tothe facility with which they are spread from the carrier to uninfected men underconditions of camp and of field service. Though the sanitary conditions undermilitary administration in this country are such as to preclude much if anyspread of these parasitic infections, under the disturbed and changingcircumstances surrounding active campaigning, carriers of intestinal parasitesassume an importance proportional to the severity of the disease the parasitesproduce and the ease and rapidity with which the infection spreads. Viewed inthese lights, one disease produced by an intestinal parasite rises to the levelwhere it demands the cure of soldiers suffering from the disease and theelimination of carriers by treatment and cure. This is ankylostomiasis.
Whereas the life of the individual bacillus of typhoid or ofdysentery is brief and the rate of multiplication of the individuals very rapid,the life of animal intestinal parasites, even of the Protozoa, is somewhatlonger, and their rate of multiplication less rapid. Massive infections, quicklyproduced, are therefore less predominant among animal parasites than with thebacteria. This is much the more striking in the case of ankylostomiasis. Thelife of the hookworm is about 7 years in the case of the male and 10 in thefemale worm. The infection is lasting, the disease chronic, and the clinicalsymptoms may arise from a relatively small number of individual parasites. Thesefacts of life history make the carrier element in the case of animal parasitesone of grave importance in the epidemiology of the disease, tend to diversifythe clinical pictures which the disease presents and to obscure the presence ofthe infection. For this reason the military surgeon may be misled as to theexistence of these infections among troops and as to their extent unless he hasthe assistance of the clinical examination of the feces to determine thecarriers.
ANKYLOSTOMIASIS
Ankylostomiasis is of considerable military significancebecause of the fact that it is in itself a disease which, in severe and chroniccases, may entirely disable the soldier. Also, in light infections it tends toincrease the chronicity
aThe data in this chapter are based, in the main, on the following articles: (1) Rapid Method for Detection of Ova of Intestinal Parasites in Human Stools, by Maj. Charles A. Kofoid, S. C., and Maj. Marshall A. Barber, S. C. Journal ofthe American Medical Association, Chicago, 1918, lxxi, No. 19, 1557. (2) The Geographical Distribution of Hookworm Infection in the United States, Detected in Army Recruits, by Charles A. Kofoid. The American Journal of Tropical Medicine, Baltimore, 1922, ii, No. 5, 389. (3) Report on parasites in overseas and home service troops of the U. S. Army, made by Maj. Charles A. Kofoid, S. C., Second Lieut. Sidney I. Kornhauser, S. C., and Second Lieut. J. T. Plate, S. C. On file, Historical Division, S. G. O.
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and severity of other diseases, and to lower the intellectualand physical efficiency of the soldier. Since infection by this parasite mayoccur directly through the skin on contact with soil or water fouled by thefeces of infected men, and since the worm, in the larval stage, may live in thesoil for a year after deposition of the eggs in the feces of man, survivingfreezing and even brief partial drying up, the spread of the infection amongtroops in trench warfare becomes distinctly possible, and the consequences ofsuch extension of the infection a matter of serious consequences to theefficiency and health of the troops. The treatment and cure of both disease andcarrier cases of hookworm infection is then a matter of military importancesufficient to justify prompt measures to detect the presence of the parasite andto cure all cases detected.
The enlisting and drafting of men for the Army from the knownarea of hookworm infection and their segregation in certain camps somewhataccording to their geographical distribution laid the basis for a masscomparison of men from these regions with those from territory in which thisinfection was not prevalent. In some instances, as at Camp Logan, Tex., and CampWadsworth, S. C., men from the North were in cantonments in the neighborhood ofothers filled with men from the surrounding territory. They were thus under thesame general environmental conditions as the men assembled in adjacent campsfrom the hookworm area.
A general opinion soon prevailed that the incidence ofdisease was relatively greater among men from the hookworm area than among themen from outside that region, an opinion since verified statistically by thestudies of Vaughan and Palmer, and later supplemented by an intensivecomparative study of the incidence of morbidity and mortality among men withhookworm and those in whom it was not detected at Camp Bowie, Tex., by Kofoidand Tucker.
In view of the prevalent opinion, the Surgeon General, onFebruary 23, 1918, directed all surgeons to take all practicable measures forthe early detection of ankylostomiasis, and for the adequate treatment of theinfected before the men became exposed to the general infections commonly foundin large camps. These instructions initiated the hookworm surveys which weremade throughout the southern camps, the results of which are the basis of thischapter. Furthermore, as a result of investigations, which were carried on inthe Southern Department, and which indicated some infection by the hookwormamong northern men who had a year or more of service in the hookworm region andamong southern men inducted from Northern States, supplemental instructions werepromulgated by the Surgeon General on August 17, 1918. These supplementaryinstructions were as follows:
All recruits and recently inducted men from the followingStates or other political divisions should be examined for hookworm as soon aspossible after their arrival in your camp: Maryland, Virginia, District ofColumbia, West Virginia, Kentucky, Missouri, Oklahoma, Texas, and all Stateslying to the south of them, and also Porto Rico, Cuba, Mexico, Hawaii, thePhilippine Islands, and other tropical countries. Troops coming from otherStates, who have been serving for six months or more in the hookworm region,should also be examined and, when necessary, be treated for the disease. Inaddition, all patients admitted to hospital should be examined for intestinalparasites as rapidly as men can be trained for the work.
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It was the aim to secure data, through the returns from thehookworm surveys made in accordance with the instructions referred to above,in the Army, which would make it possible to map the distribution of hookworminfection in the known area of its occurrence, and to detect its presenceelsewhere in the United States, since the drafted men represent in the main anideal cross section of the population owing to their ratio to the totalpopulation and the nature of their selection. It would hardly be possible by anyother available method, except by a complete school survey, to secure asrepresentative a group of the population in such a test. However, owing to thefact that Medical Department Form 55 n, used in reporting laboratoryexaminations of feces, does not give the home address of the patient, and to thefact that the routine hookworm surveys, with few exceptions, were not soconducted as to provide rosters with the home address or place of enlistment ofthe men examined except in a few isolated organizations, it was not practicableto furnish the geographical data in the amount desired.
METHODS USED FOR THE DETECTION OF OVA OF INTESTINAL PARASITES
Since no orders prescribing the method to be used in thedetection of ova of intestinal parasites were promulgated by the SurgeonGeneral's Office, it is appropriate here to describe some of the methods morecommonly used throughout the camps, and to indicate their comparative values.
Because of the numbers to be examined, the nature of theavailable equipment, and the desirability of not encroaching on the duties of amedical staff already occupied with more important work, it was essential thatany method used in detecting infection by intestinal parasites, such ashookworm, should be adapted to the utilization of an untrained and changingpersonnel in large part, and that it should not require elaborate apparatus orextensive laboratory equipment.
The direct microscopic examination of a sample of the fecalspecimen is inaccurate and inadequate because of the minuteness of the sampleused, and impracticable because of the length of time required to make a fairexamination. The greater efficacy of the brine flotation-loop, described below,in the detection of the worm ova as compared with the ordinary smear method isshown in Table 89, in which daily examinations for nine-day periods arecompared. Only hospital cases, based on records at Camp Jackson, are included inthe table. The great variability in the daily hookworm percentages is probablydue to the varying proportions of patients from the Northern States. The brineflotation method is obviously inferior in the detection of Strongyloides.
The centrifuge method was at once precluded by thedifficulty, if not impossibility, of securing at the time an adequate number ofinstruments to accomplish a work of such magnitude, and the added difficulty ofsecuring the requisite tubes and other glassware essential to equip and maintainfacilities adequate to care for the number of examinations to be made in asurvey of troops from the hookworm area of the South. It also calls forextraordinary care in cleaning the glassware used, for hookworm eggs are quiteadhesive to the surface of glass. This is a difficulty of considerableimportance when laboratory helpers are inexperienced, and adds much to theburden of supervision.
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TABLE 89.-Comparative results in detectionof ova by direct smear and brine flotation-loopmethods
ORDINARY SMEAR METHOD
1918, June- |
| Positive hookworm | Percentage positive | Remarks | |
10 | 205 | 13 | 6.3 | During nine-day period the same examinations as that for the hookworm gave these percentages of other worms: | |
11 | 132 | 23 | 17.7 | ||
12 | 153 | 24 | 15.7 | ||
13 | 135 | 19 | 14.1 | Ascaris | 1.1 |
14 | 150 | 11 | 7.3 | Hymenolepis nana | 0.6 |
15 | 116 | 9 | 7.7 | Trichuris | 0.3 |
17 | 144 | 3 | 2.1 | Strongyloides | 0.6 |
18 | 106 | 14 | 13.2 | Oxyuris | 0.0 |
19 | 99 | 11 | 11.1 |
| |
|
| 1,240 | 127 | 10.2 | ||
|
| |||||
20 | 109 | 40 | 37.5 | During nine-day period the same examinations as that for hookworm gave these percentages of other worms: | |
21 | 96 | 34 | 35.4 | ||
22 | 146 | 50 | 32.1 | Ascaris | 1.1 |
24 | 146 | 48 | 34.1 | Hymenolepsis | 0.8 |
25 | 152 | 39 | 26.2 | Trichuris | 0.8 |
26 | 128 | 26 | 20.3 | Oxyuris | 0.08 |
27 | 120 | 26 | 21.7 | Strongyloides | 0.0 |
28 | 120 | 22 | 18.3 |
| |
29 | 116 | 25 | 21.6 | ||
| 1,133 | 310 | 27.1 | ||
The centrifuge is also inaccurate, undoubtedly because of thesmall size of the samples used. The standard fecal sample collected for thismethod in the Army is contained in a 2-dram vial. Negatives for hookworm by thismethod as used by the author in the department laboratory of the SouthernDepartment were examined by the brine-flotation method and found in about 50examinations to show a 40-per cent increase in infections. That is, thepercentage was increased from 10 to 14. This ratio was borne out by the factthat, whereas the percentage of infection by the centrifuge method was about 8per cent in 7,000 examinations, made in March, 1918, at the departmentlaboratory, Southern Department, it rose at once to from 14 to 20 per cent amongtroops from the same general localities when the brine-flotation method wasapplied.
The sieve-sedimentation method of Hall is not adequate to themilitary necessities because of the fact that it can be operated only in awell-equipped laboratory and requires an expensive, elaborate, and somewhatpermanent installation. It seems not to be rapid, and would require great carein cleaning to prevent a carrying on of infection when the sieves are used inrapidly succeeding examinations. Its accuracy in cases of light infectionsshould also be tested. The prime difficulty, however, with this method forhookworm survey is that arising from the possibility of carrying over ova frompositive to negative stools and thus reporting a man for treatment who carriedno infection.
BRINE FLOTATION-LOOP METHOD
In view of the difficulties, under Army conditions, attendingthe use of the methods referred to above, the method here described was devisedafter considerable experimentation. The method finally perfected by Kofoid andBarber
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may be designated as the brine flotation-loop method. Itconsists in mixing a large fecal sample thoroughly in concentrated brine, in aparaffin paper can of from 2 to 3 ounces capacity, forcing the coarse floatbelow the surface by means of a disk of No. 0 steel wool, and then allowing thecan to stand not more than one hour nor less than 10 minutes for the ova toascend. The surface film is then looped off with wire loops, one-half inch indiameter, and examined on a slide without a cover glass.
The method was tested in the Southern Department under theauthor's direction in more than 100,000 examinations of varying ratios anddegrees of infection by about 75 different examiners, under diverse fieldconditions, and was found to be efficient and practicable.
TECHNIQUE
The stools for examination were collected at reveille at thecompany latrines by a collecting squad consisting of 16 enlisted men in chargeof a sergeant and under the supervision of a medical officer. The men from agiven company were in charge of a line officer. They were marched to the latrineand the roll was called in alphabetical order from the roster by the sergeant incharge of the men. On admission to the latrine each man was identified and givena container, bearing the designation of the organization and his roster number,a sheet of waterproof paper, and half of a tongue depressor as a collectingstick. He was instructed to defecate on the paper and fill the can one-thirdfull of feces. Men unable to furnish a specimen were given salts, under thesupervision of the medical officer, and were moderately exercised. The mensubmitted their samples to the collector for inspection on leaving the latrineto prevent the passing in of empty cans. Substitution was forbidden. In practicethis squad could collect the specimens from an entire regiment, make the firstdelivery at the laboratory at 7.30 a. m., and complete the collections at 10 a.m. On an average from 3 to 10 per cent of the organization on a complete rosterfailed to furnish specimens by reason of absence, detached service, or failed todefecate.
The receptacles used as containers for fecal specimens forexamination for ova of intestinal parasites served not only to receive the fecalspecimens at the latrines but also as the mixing dishes from which the ovasubsequently were looped for examination, and themselves bore the results oftheir examinations to the recorder's table. The use of glass or tin containerswas precluded by the cost, labor of cleaning, and danger of carrying over ofinfection by adhesion of ova to the sides of the dish; therefore, paper andpasteboard containers, which would be wasted afterwards, were used. Inemergency, paraffined paper drinking cups and standard hospital sputum cups wereused, but the most satisfactory container proved to be the standard 2-ounceparaffined paper drug can with tin bottom and paper top. Similar cans with paperbottom and top are more liable to be unsealed by the solvent action of thecontents. Tin tops are advisable if specimens are to stand many hours beforeexamination. Open drinking cups permit evaporation and increase the odor andliability of carrying over of ova by flies. Heavy paraffined "Kleen Kup"tumbler-shaped containers used in the grocery trade are satisfactory forshipping specimens some distance.
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These have disk tops which may be forced into a groove. Theyare water-tight, preserve their contents admirably, and may be washed and usedseveral times. They are difficult to write upon, except with wax pencil,difficult to open, and have an excess of surface exposure.
The drug cans which were used most extensively are about 1?inches in diameter and 2? inches high and are made up from speciallyconstructed paper tubing made from stock paraffined on the inner face. Theircapacity is normally 2 ounces and varies from 50 to 80 c. c. according to thebrand or factory. Certain brands either have no coating or are so lightly coatedthat it was necessary to treat them to a dipping or to an inside coating of hotparaffin or sodium silicate to render them brine proof. Brine-proof cans,paraffin-coated on the inside that will resist soaking up by brine and feces fora number of hours can be obtained from commercial sources and are fairlysatisfactory for this method of stool examination. The practical advantage ofcontainers of these dimensions is that they will pack snugly in the compartmentsof the pasteboard fillers, which hold 3 dozen each, of standard shipping casesfor eggs, which hold 30 dozen each. To facilitate the handling of a singlefiller, specially constructed pasteboard trays with tape loops for handles intowhich a single filler fits were used. These trays are very convenient for use inthe preliminary marking of the cans, the arrangement of the numbered cans, andfor subsequent handling at the latrines and in the laboratory.
In the examination of troops in the Army each can was markedwith the designation of the organization and the roster number of the man whosespecimen it was to receive. Thus, 305 Cav. H-16 was for the sixteenth name onthe roster of Troop H of the 305th Regiment of Cavalry. Cans were at firstmarked on both top and side; the former for convenience in picking out aparticular can at the latrine, the latter for use in the laboratory. These canswere marked with wax pencils or on strips of adhesive tape in ink on the tintops, and the sides similarly marked, or with lead or colored pencil or in ink.Pasted typewritten labels are unsatisfactory, as they may soak off if wet orpeel away if dry. The most satisfactory labeling proved to be that written in"Eternal" ink. This is not removed by water or brine, and sinks intothe paper so deeply that it can not be rubbed off. It is also clearly visible onthe wet can.
The cans for a given organization, such as a company orregiment, were serially numbered, and on receipt at the laboratory from thelatrines were usually not in numerical order. In order to detect shortages,eliminate confusion of indistinctly written numbers, and facilitate enteringresults on the numerically and alphabetically serial roster, the cans were firstarranged in numerical order on a number board and then racked in order in thesockets of serially numbered wooden racks holding 10 cans each. They were thenpassed to the mixing table, where they were prepared for the examiners.
The stool was prepared for examination by stirring thespecimen thoroughly in concentrated brine with a small wooden stick until thebrine was considerably discolored and the contained ova released from the feces.The amount of stool to be stirred varied with its consistency and composition.Not more than one-third of a canful ordinarily was used; if the sample submittedwas too generous
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the amount was reduced. The can was nearly filled with brine,and the stool, if puttylike and resistant, was broken up against the sides ofthe can. In some instances of puttylike stools the release of the ova wasfacilitated by scouring the stool up with steel wool on the end of the stick,against the side and bottom of the can. After stirring until the desiredconsistency was attained, a circular filter of No. 0 or No. 1 long fiber steelwool was carefully pushed down through the fluid to the bottom of the can withthe stick. This effectively removed from the surface the lighter coarser float,broke imp the air bubbles, and left the surface clear of coarse particles andsuitable for looping the floating ova. Stirring the stool with the electric sodamixer gives quickly a suspension of the stool, but forms too many air bubblesfor satisfactory looping. These may be quickly removed, however, by a few dropsof alcohol or ether. If too much wool is used it will interfere with the ascentof the ova; if too little is used it will not remove the float. As a rule alightly compressed disk, one-eighth to one-fourth inch in thickness, issufficient. From 1 to 2 pounds are sufficient for 1,000 specimens. Othermaterials, such as disks of gauze or wire netting, or mats of excelsior andsouthern moss, will serve the same purpose, but less successfully by far. Thesouthern moss may introduce fresh-water nematodes and their eggs and larv?.
Since there was danger of cross contamination of adjacentcans through stirring and in putting in the wool by splashing over from one canto another, each can was removed from the rack during the preparation. As anadditional precaution to prevent the accidental transfer of a stick from one canto another during the mixing of a rack of cans, it was customary to place sticksin all of the cans at the beginning of the work on the rack and leave them therewhen not in use until the entire rack was finished.
The specimen was prepared for microscopic examination bylooping of the surface film to an ordinary glass slide. The loops for thisoperation were prepared from unraveled window screen or similar fine galvanizedwire. They can be made up rapidly from 6-inch squares of wire netting byunraveling the mesh and twisting the individual wires into the loops. Each loopwas formed around a glass tube or wooden cylinder about three-eighths of an inchin diameter, the shorter end twisted around the longer, which formed the shaftto close the loop, which was then bent out at right angles to the shaft. It wascustomary to let the cans stand for one hour to allow the ova to accumulate inthe upper layers.
The following test shows the relative hourly abundance ofhookworm ova in the surface film on a can mixed with brine at 8.45 a. m., untilthey disappeared: The brine and ova were poured off into another can at 9.15,being distributed, by the pouring, throughout the fluid. Four loopfuls wereplaced on the slide and 10 fields were examined. At 9.15 there were 69 ovarecorded; at 10.20, 169, at 11.30, 150; at 1 p. m., 85; at 2.10, 20; at 3.15,only 3; and at 4 p. m., none. The temperature during the period was from 90? to95?. The maximum number of ova appeared at the surface about an hour after theywere uniformly stirred, and seven hours after mixing all had descended from thesurface.
From tests made under other conditions it is evident thatthere is considerable variation in the rate of ascent and descent of the ova inthe brine in different stools and at different temperatures.
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The surface film will usually adhere to the wire when thesubmerged loop is lifted from the brine. Ova in the film are removed with it. Itproved advisable to loop the surface near the sides as well as the center of thecan. For this purpose the loop may be molded to the arc of the can on the oneside. An acute angle in the loop at the base of the shaft is to be avoided as ittends to break the film.
The number of loopfuls necessary to make a fair sample formicroscopic examination depends on the viscosity and contents of the filmremoved. About 10 loopfuls will skim the entire surface of the can and form apool of brine conveniently handled on an ordinary microscopic slide with amechanical stage. One skimming does not by any means remove all the ova, as theyare not all in the immediate surface.
To secure the even spread of the looped film on themicroscopic slide it is essential that slides be thoroughly cleaned withsulphuric acid-bichromate of potash mixture or with soap to remove all trace offat. The custom of looping more than one sample on a single slide each in itspenciled area is to be avoided because of the droplets which are sprayed aboutat times by the breaking of the film on the loop, and thus giving rise to crosscontamination of the adjacent pool by an infected film.
For a time the author marked off an ellipse 1? inches bythree-fourths inch on the slide with a wax pencil to assist in confining thepool of brine on the slide, but this was later abandoned as unnecessary. It alsoincreased the labor in cleaning the slide.
In the cases of viscid, opaque, and fatty stools,considerable dilution may be required. This may be done on the slide with a fewdrops of a mixture of equal parts of glycerin and brine stirred into the pool.The glycerin clears the more opaque particles and renders the ova more easilyvisible.
Contamination of the adjacent cans by droplets of the surfacefilm splashing over from an infected can to a negative one may readily occur whenthe loop catches on a stray fiber of the steel wool and is suddenly released, orwhen the film in the loop breaks on contact with the slide. For this reason thecan and slide should be moved away from the rack while the pool is being loopedoff.
The viscosity of the surface film may vary greatly with thenature of the stool. It is markedly decreased by slight additions of suchdisinfectants as tricresol and phenol (carbolic acid) or by alcohol, which isuseful in removing air bubbles from the surface. Formaldehyde solution tends tocurdle the mixture, and delays the ascent of the ova and reduces the numbers inthe surface film.
These variables, which affect the opacity of the filmexamined and contents of the loop and the number of ova it removes, render anyuniformity of looping and resulting thoroughness of examination practicallyimpossible. In practice, from 3 to 7 loopfuls are generally used; but the numberin the course of numerous examinations will vary from 1 to 20. It is obviousthat these variables will introduce a margin of error in the detection of ovaonly among the lighter infections.
The surface of the pool of brine is thoroughly searched withthe aid of the mechanical stage. To reduce the amount of focusing, the convexityof
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the surface of the pool may be reduced by spreading it overthe slide and extending the amplitude of the movements of the mechanical stage.
The microscopic equipment most useful is the typicalhigh-grade instrument with 16 and 4 mm. objectives and x 5 or 6.4 and x 10oculars or their equivalents. The searching is done with the low-powerobjectives and low-power ocular, since the latter is less tiring inlong-continued examinations. For closer scrutiny the 4 mm. objective may be usedwith care on objects in the surface film without cover glass.
To render the ova more distinctly visible it is essentialthat the microscope be provided with a substage condenser and that theillumination be reduced by closing the iris diaphragm or lowering the condenserso as to increase the sharpness of definition of all objects in the field and tobring the egg membranes into relief. This assists in the quick differentiationof ova from objects of similar shape and opacity. The amount of searchingnecessary to make a fair examination is a function of so many variables that noarbitrary rule can be laid down. The degree of dilution, stirring, flotation,the amount of the surface fluid in the pool, its extent and convexity, theconsistency and opacity of the fluid and its solid contents, the nature andnumber of the particles floated to the surface, the number and size of airbubbles, fat cells, oil globules, and starch cells all combine to complicate thesearch for ova. It is advisable to search a considerable area rapidly, andespecially, in the case of opaque fluid and confusing particles, to search apart of the area minutely or make an additional dilution. Experienced examinerson an average give from two to three minutes to the examination of a specimencontaining on an average four or live loopfuls spread over an area ofapproximately 1.5 square inches on the slide.
Infected stools, or positives, are usually detected in thefirst field or run across the slide examined. In a test case of 550 positives ofhookworm, most of them very light infections, in Oklahoma and Texas recruits,detected on five consecutive days by five experienced examiners and recorded asfound or not in the first run across the slide, there were 180, or 30.5 percent, reported as seen in the first run. Infections obviously reduce the timerequired for examination in most cases. In a relatively few cases, estimated atnot more than 5 per cent, with the examination of more than 150,000 men in theSouthern Department (Texas, Oklahoma, New Mexico, and Arizona), several ova onlywere found in the whole slide examined. In rare instances only a single ovum isfound. These very light infections and the negatives require more time for acomplete examination than do other positives.
It is obvious that the rate of examination and daily score ofthe examiner will be in part a function of the ratio of positives to the wholeand of the average degree of infection. With numerous positives and heavyinfections, which are usually coincident, the rate of the expert examiner mayeasily be doubled over that when positives are few and infections are light. Theexperience, skill, industry, and thoroughness of the examiner are also factorsdetermining his daily score, as well as the nature of the stools as conditionedby diet and modified by the skill or lack of it on the part of the mixers.
A skilled examiner will complete from 150 to 250 examinationsdaily under average conditions. With the assistance of a looper the rate can be
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speeded up to one per minute; or over 400 per day, but theresulting eye strain renders this inadvisable as a daily routine. A staff of 15examiners can maintain a rate of from 2,000 to 2,500 examinations daily andattain 3,000 under favorable conditions of cooperation and effective supervisionof the mixers. A staff of 20 examiners can complete a full regiment daily.Supplemental aid of approximately one man in the field collecting squad, in casethe collecting is done by the men attached to the surveying board, and one manin the laboratory and clerical squad for each examiner is necessary to collect,prepare, record, and dispose of the specimens and attend to the policing of thelaboratory.
The time required for the physician inexperienced inlaboratory work to become efficient in this method is brief. Enlisted men withsome experience in college, university, or Army laboratories acquired a reliabledegree of accuracy with several days' training and supervision, as shown bytest. Insistence upon focussing upon the surface film and a preliminaryexercise and testing out in stools with known infections are essential inpreparation for this work.
The ova of parasites such as Ancylostoma duodenale,Necator americanus, Ascaris lumbricoides, Oxyuris vermicularis, Trichuristrichiuria, T?nia solium, Hymenolepis nana, Hymenolepis diminuta, and Dipylidiumcaninum and of trematodes, are floated up by the brine into the surfacelayer of the pool without distortion or noticeable change in appearance duringthe usual period of examination. Cysts of Entamoa coli and histolyticaand of Giardia intestinalis are also floated up. Since the ova are atthe surface, it is not advisable or necessary to use a cover glass.
MODIFICATIONS OF THE BRINE FLOTATION-LOOP METHOD
The exigencies arising in the Army from the shortage ofsupplies for the brine flotation-loop method, and the devices of officersresponsible for the hookworm survey gave rise to a number of modifications ofthe original method. The simplest of these is Barber's method, in which agood-sized lump of feces is mixed with glycerin and saturated sodium chloridesolution (proportions not important) and a drop of the mixture placed on a slideringed with a wax pencil. The eggs float to the surface and rise to the centerof the drop.
The following modification of the brine flotation-loop methodwas made at Camp Jackson, S. C., for routine hospital examinations and for anumber of stools sent from the camp:
Specimens were sent to the laboratory in tin containersprovided with lids. Brine flotation and loops were used exactly as in the methoddescribed above, but instead of filtration by steel wool the coarser floatingparticles were skimmed off by means of a spoon before the ova had time to rise.The spoon was scrubbed with a brush and carefully washed under the hot-watertap after each use. When cans were used a second time they were very carefullycleaned and dried.
It is obvious that the main advantage of this modification isin the saving of materials rather than of labor. Further, it is adapted only towork on a comparatively small scale and in a laboratory supplied with trainedworkers and with a hot-water tap for the proper cleaning of utensils. It is notto be
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recommended for field work on a large scale or for any workin which pasteboard containers and steel wool are obtainable, or where expensefor labor is a factor. The possibility of removal of some of the ova by thismethod is not precluded.
The lack of the drug cans led to the use of standard hospitalsputum cups for collection and stirring in brine. These answer the purpose, butthey are less substantial than the drug cans, more difficult to stir in,attract flies (because they have no cover), permit the stools to dry up onstanding, and owing to their proportions they give a greater dilution of the ovain the surface film. For these reasons they are to be avoided when feasible.
ACCURACY OF THE BRINE FLOTATION-LOOP METHOD
The accuracy of the method may be reviewed from thestandpoint of its relative efficiency as compared with other methods,considered above, with the conclusion that, with the exception of the culturemethod, it offers the highest attainable degree of accuracy, with a maximumrapidity, and a minimum amount of labor in cleaning and loss by breakage, and aminimum of expense for materials used.
Not all positives can be determined by any method short ofautopsy after sudden death, for worms may be voided during sickness as a resultof, or treatment for, disease, or males only may be present. Owing to variationsin the physiological states of host and parasite, ovaposition is subject toirregularities resulting in marked changes in numbers of ova discharged in thestool, with the result that quite independently of the accuracy of the examineror of the technique employed, the infection is not revealed in the stool. Withinan as yet unknown and presumably variable range of materials, the size of thesample examined, as determined by the size of the sample collected, on the onehand, and by the amount of material subjected to uniform scrutiny by theexaminer, on the other, sets a certain limit to the accuracy of the work. Largesamples will yield more positives than small ones in light infections, but nomethod in itself will reveal ova in the stool when the worms are not ovapositing.Repeated examinations on successive days, or at intervals, are necessary toestablish a negative.
The relative accuracy of this method, among examiners andspecimens, depends on a number of variables, the size and consistency of thespecimen, the thoroughness of stirring, the proper amount of steel wool, thecare in looping, the opacity of the fluid, and the extent and thoroughness ofsearch made of the material on the slide. Much depends on keeping the focusdirectly on the surface of the fluid during examination and in training theeye to detect quickly every object resembling an ovum.
The cases of infection which escape detection are the verylight ones in which only a few ova can be found on a slide. Some slides preparedfrom such infections may have no ova, or the ova may be hidden or overlooked.
Reexamination of slides and cans that are reported by anexperienced examiner as negative will sometimes reveal a positive, lightlyinfected. Men reported as negative on a first examination may appear as positiveon a second, and vice versa. This raises the question as to the uniformity ofdistribution of
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the ova in the stool and as to the possibility of internalstates of host and of parasite influencing the rate of deposition of ova insuccessive stools.
With a view of testing out the possibility of lightinfections having been overlooked, an examination was made of 100 negatives fromcolored troops at Camp Travis, Tex. Infections in the battalions from whom thesenegatives were drawn were only 68 in 1,495, or 4.8 per cent. The infections werealso light, as a rule. The top fluid of 50 cans was drawn off into a tallcylindric liter graduate and the surface film of this column examined. The canshad stood after stirring for less than three hours, and no brine from thick orviscous stools was used, so as to avoid entangling any ova that might bepresent. This was repeated on a second 50 and the top fluid of the two lotscombined in a slender 50 c. c. graduate. An examination of the surface film ofeach of these concentrations gave negative results. A subsequent examinationwithin two hours of flotation of 150 negatives by the same method from whitetroops, showing 219 positives, or 8.7 per cent, in 2,505 examinations, revealed1 case of an ovum in 1 lot of 50. The other two lots remained negative. Inanother test of 3 lots of 50 each from white and colored troops showing 110infections, or 5.7 per cent, in 1,914 examinations, all remained negative. In atotal of 550 negatives, or 11 lots of 50, of light and therefore presumablyeasily overlooked infections, only one lot showed evidence of an undetectedinfection on this test.
It appears from these tests that the number of positivesescaping detection by the brine flotation loop method is small. These tests weremade in the negatives from 16 examiners, 13 of whom were enlisted men and 8 ofwhom had only from 3 to 9 days experience with hookworm examinations.
No opportunity occurred for a comparison of this flotationmethod with the culture method to compare their relative accuracy on identicalstools.
GEOGRAPHICAL DISTRIBUTION OF HOOKWORM INFECTION IN THE UNITED STATES
Examinations of recruits for hookworm in the Army camps,conducted by the Medical Department in accordance with the instructionspreviously referred to, afforded unique opportunities of detecting the extentand distribution of infection by this human parasite. The distribution thusdetected is not that of the infected population of the country as a whole, butrather that in a selected group of able-bodied men, most of whom had already runthe gantlet of one or more medical examinations, and were, at the time of theexamination, in Army camps on duty as able-bodied soldiers, or in some stagepreparatory to this status. They presented, therefore, to a considerable degree,a selected group, since the obviously sick had been excluded.
The data also include only males, presumably the sex mostexposed to infection. Furthermore, the males included were not those of allages, but only those of military age, the general body of whom were between theages of 21 and 30, with certain numbers below 21 and above 30. They representeda fair sample of able-bodied young men of the United States of southernresidence or exposure with but slight modifications due to selective factorsand class of occupation. These selective factors would tend to modify somewhatthe representation of classes most liable to infection, especially in somecases, such as agricultural exemptions, which tended to counteract the inclusionof the normal representation from agricultural districts in the hookworm area.
541
Not all of the States are represented equally in the data,since the orders of the Surgeon General's Office covering these examinationsprovided only for the examination of men who entered the Army from the hookwormarea, or had resided there for six months or more, or who had formerly lived inthat area but had emigrated to other States of the Union. Percentages ofinfection therefore which appear for States other than those of the hookwormarea are not representative of the normal population of those States, but ratherof a selected group of persons who lived within the area of distribution ofhookworm and thus came within the possibility of exposure to infection byhookworm.
Our data, therefore, are fairly representative of the normalpopulation of males of military age only for States of the hookworm area andonly those males of military age who in other States might have acquired theinfection by reason of southern residence.
The total number of men examined for hookworm in the UnitedStates Army during the war and so reported to the Surgeon General was 501,472;of these, 56,740, or 11.3 per cent, were found to be infected with thisintestinal worm, upon one examination as a rule. Had repeated examinations beenmade by the brine flotation method in all cases this percentage would have beenincreased, perhaps from 25 to 50 per cent. Unfortunately the Army records didnot permit the allocation of these men to the States of their birth, residence,or enlistment in most of the cases. This was feasible, however, in the case of126,140 men.
In order that the contrast between the different areas of theUnited States may be set forth in their relations, the statistics have beengrouped under four heads: States in the hookworm area (16 and District ofColumbia); 10 of the Northeastern States; the 13 States of Northern MississippiValley, or Middle West; and 10 of the Pacific Slope, including Alaska.
TABLE 90.-Hookworm infection in States in the hookwormarea
State of birth |
| Number positive | Number of men examined | State of birth | Per cent positive | Number positive | Number of men examined |
Alabama | 29.4 | 656 | 2,223 | North Carolina | 27.1 | 3,402 | 12,558 |
Arkansas | 6.4 | 787 | 12,292 | Oklahoma | 6.9 | 607 | 8,686 |
District of Columbia | 1.6 | 2 | 121 | South Carolina | 23.5 | 1,918 | 8,135 |
Florida | 31.8 | 1,202 | 3,778 | Tennessee | 12.6 | 1,233 | 9,722 |
Georgia | 32.6 | 1,265 | 3,872 | Texas | 11.7 | 3,494 | 29,837 |
Kentucky | 16.3 | 376 | 2,301 | Virginia | 6.7 | 65 | 969 |
Louisiana | 27.3 | 2,010 | 7,348 | West Virginia | 3.7 | 36 | 972 |
Maryland | 2.1 | 12 | 584 | Total | 17.01 | 19,464 | 114,408 |
Mississippi | 27.1 | 2,358 | 8,684 | ||||
Missouri | 1.8 | 41 | 2,326 |
TABLE 91.- Hookworm infection in the Middle West-Mississippi Valley
State of birth |
| Number positive | Number of men examined | State of birth | Per cent positive | Number positive | Number of men examined |
Illinois | 1.4 | 17 | 1,153 | North Dakota | 0 | 0 | 82 |
Indiana | 1.7 | 10 | 582 | Ohio | 3.5 | 45 | 1,277 |
Iowa | .4 | 2 | 418 | South Dakota | 1.6 | 1 | 63 |
Kansas | .8 | 3 | 354 | Wisconsin | .7 | 2 | 278 |
Michigan | 1.0 | 7 | 665 | Wyoming | 0 | 0 | 41 |
Minnesota | 1.5 | 5 | 325 |
| 1.69 | 96 | 5,664 |
Montana | 1.2 | 1 | 81 | ||||
Nebraska | .9 | 3 | 345 |
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TABLE 92.- Hookworm infection in the Northeastern States
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|
|
|
|
|
| |||||||||
| Connecticut | 1.1 | 4 | 265 | New York |
| .7 | 11 | 1,479 | |
| Delaware | 8.7 |
| 2 | 23 |
| Pennsylvania | .3 | 4 | 1,074 |
| |||||||||
| Maine | .9 | 2 | 216 | Rhode Island |
| 1.3 | 1 | 73 | |
| Massachusetts | .1 | 9 | 813 | Vermont | 1.1 | 1 | 84 | ||
| |||||||||
| New Hampshire | 14. 2 | 2 | 47 |
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|
| |
| New Jersey | .3 | 1 | 284 |
TABLE 93.-Hookworm infection in the Pacific Slope States
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|
| |||||||||
| Alaska | 0 | 0 | 1 | New Mexico |
| 2.6 | 9 | 345 | |
| Arizona | 3.1 |
| 4 | 128 |
| Oregon | 2.4 | 2 | 81 |
| |||||||||
| California | 2.0 | 11 | 527 | Utah |
| 3.2 | 2 | 61 | |
| Colorado | 2.4 | 9 | 368 | Washington | 2.1 | 3 | 137 | ||
| |||||||||
Idaho | 2.7 | 1 | 38 |
|
|
|
|
| |
Nevada | 8.3 | 2 | 24 |
SUMMARY
Total number of men examined | 126,140 |
Total number positive | 19,640 |
| Per cent infected | 15.5 |
The number of men examined, according to these tables, is126,140, among whom 19,640, or 15.5 per cent, were found to be infected byhookworm. The percentage of infection in the men outside the hookworm area owesits origin to two factors, the relative importance of which it is not possible,owing to the nature of the data, to disentangle from available records. Thesetwo factors are infection due to birth or residence in childhood or later lifein States of the hookworm area, on the one hand, and, on the other, to exposurein southern Army camps or service on the Mexican border on the part of recruitsin the Army in the years prior to the World War, and service in Army camps inthe hookworm area for more than six months after the United States entered thewar. Owing to the sanitary supervision in Army camps, it is highly improbablethat many cases of hookworm infection could have been acquired by men of thelatter group during their period of Army service. The inclusion of these twogroups of men among those accredited to States outside the hookworm areaundoubtedly has tended to decrease the percentage of infection reported forthese States. Had the examinations been limited to men of southern birth orresidence outside of Army service the percentage would possibly have beenhigher, because of the varying degrees of sanitary supervision during periods ofresidence and the tendency for many of these periods of residence to have beenmore prolonged than those of Army recruits.
In view of these considerations, it is evident that thedegree of suspicion of hookworm infection which attaches to persons of birth orresidence in the hookworm area and subsequent migration to States outside ofthat area must be somewhat higher than that suggested by the percentages ofinfection here reported. Thus, for example, in the State of Illinois, in which1,153 men were examined, there were 17 men, or 1.5 per cent, found to beinfected with hookworm. It happens that Illinois recruits at Camp Logan, Tex.,who had been
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there for more than six months, were examined for hookwormand constituted a considerable proportion of the persons accredited to thatState. In that camp, among 7,539 patients at the hospital, 7.4 per cent werefound to be infected, while in 4,807 men on duty in the 15th Division, thepercentage was 2.4. This percentage is higher than that accredited to the Stateof Illinois, because of the infiltration into this camp of other recruits,largely from the hookworm area. It is impossible to determine the extent towhich the 2.4 per cent among troops on duty in this camp was due to infectionsacquired during residence therein, or to determine in what degree the 1.5 percent accredited to the State of Illinois was due, on the one hand, to migrationfrom the South into that State, and, on the other hand, to local infectionacquired by recruits born in Illinois and subsequently residing in the southernArmy camps. The presumptive evidence is against the acquirement of theinfection in the camps, owing to the sanitary supervision of food and oflatrines and the wearing of shoes. Only under the most exceptional circumstanceswould a recruit be exposed to infection by contact with polluted soil or foodor water.
Certain sources of error are inevitable in so large a mass ofdata as this, gathered under circumstances so diverse. These errors arise fromvarying methods of examination. All of the examinations are subject to errorsarising from a single test. Repeated tests would undoubtedly have increasedthe number of infections perhaps as much as 30 per cent, and 10 per cent ifexamined by the brine-loop method. The lighter infections by few worms are oftenoverlooked or undetected in cases of a single examination only. The percentagesof infection here reported fail to represent adequately the degree of infectionprevalent, because of the fact that the group of men included are of the age inwhich infection acquired in childhood is gradually dying out, especially incases under consideration in which changes ensued from rural to urban lifeand from barefoot days to those of the constant wearing of shoes. These changescut off the opportunities for renewed infection, and combined with the dyingout of worms from old age, tend to eliminate in the older men of the group theinfection of earlier years.
Imperfect as these figures of necessity are, still theyindicate that there is much to be done in sanitary supervision, not only inmilitary camps but by local and State boards of health, by educationalagencies, by industrial organizations, and by other institutions interested inthe improvement of the sanitary conditions and of the health and efficiency ofthe community.
INTESTINAL PARASITES IN CERTAIN OF THE OVERSEAS ANDHOME-SERVICE TROOPS
In the Army laboratory, port of embarkation, New York, fromDecember 28, 1918, to July 1, 1919, examinations were made of 2,300 men of theUnited States Army who had been overseas and of 576 men from home-servicetroops. The overseas troops examined were sick and wounded soldiers in transitthrough Debarkation Hospital No. 3, New York City; they were drawn from over800 different military organizations, and therefore were fairly representativeof our overseas troops. They came from every State in the Union andconstituted approximately a fair example of our population. Only a smallfraction of them saw service on the Mexican border.
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The home-service troops were mainly cooks, bakers, and foodhandlers from the port of embarkation, principally from the Medical Department.Of the total of 576 men examined, about 30 per cent were of foreign origin-Russian, Polish, Italian, or Spanish-or were negroes from Florida. This group,therefore, was less typical of the American troops as a whole than was theoverseas group examined. They presumably presented a higher degree of infectionby reason of their origin than would a fair sample of our population.
The relative degree of infection in these two groups of menwas striking, as will be shown later, but it is obviously impossible todetermine what proportion of the infection detected in the first group wasacquired overseas and which was of home origin.
For the determination of infections, reliance was placedmainly upon the microscopical analyses of ova and cysts in the fresh stools.Different methods for the protozoa and for helminths were used in this analysis,the ova of the latter appearing in only a small number of cases in the directsmear method, which proved most useful for the former. For the protozoanexamination a modified Donaldson's iodine-eosin stain was used. The smear isprepared for microscopical examination by rubbing out a minute bit of the fecesby rolling it on a round applicator stick in a small drop of normal saltsolution and then in an adjacent drop of the iodine-eosin stain. A single coveris placed on both drops and the smear is ready for immediate examination. Livingflagellates, active ameb?, and unstained cysts appear in the unstained part. Inthe stained area the bacteria, fecal particles, and the smaller intestinalyeasts stain at once. Against the pink background the protozoan cysts stand outclearly as bright, greenish spherules, which soon become tinged by the iodine tovarying tones of yellow. When glycogen-laden vacuoles are present they becomelight or dark brown, according to their mass. The nuclei, which at first arescarcely if ever visible, become more clearly defined as the iodine penetrates,expecially in Entamoba coli and histolytica. They are detectedwith difficulty in this stain in E. nana.
The component solutions of this stain were prepared inphysiological salt solution and the proportions of iodine as given in theoriginal formula were reduced. The formula is used as follows:
|
|
Saturated solution eosin in normal salt | 2 |
Five per cent KI in normal salt saturated with iodine | 1 |
Normal salt solution | 2 |
Also the concentration method of Cropper and Rowe (1917), asmodified by Boeck (1919), was used on over 2,000 stools as supplemental to thedirect smear, but less than 10 per cent was added to the number of infectionsdetected by the direct smear method. A few trials of the Carles-Barthelomy(1917) citric-formalin method also were made. The added infections were mainlyof E. coli, which is rarely abundant, a few light infections of E.nana, and a few cases of Giardia. It is probable that the detection of lightinfections of E. histolytica would be facilitated by these methods, butthe time required is greater and the percentage of infections detected therebyvery small. The direct smear is simple, rapid, and in our experience bothefficient and reliable for practical purposes. Concentration methods were usefulin research and in following up difficult and suspected cases.
545
In nearly all cases of infections with Entamobahistolytica and with the smaller races of E. nana preparations weremade by the wet smear and stained with Heidenhain's slow iron hematoxylin.This also was used to confirm the analyses made in all doubtful cases.
Examinations for ova of intestinal worms were made by thebrine-loop method.
A single examination only was made in most cases. Theexceptions to this were 60 men from overseas and 71 of the home-servicetroops, from whom two or more samples were secured for examination. In theoverseas group the reexamination of 60 cases with a total of 129 examinations,or 2.15 examinations per individual, increased the number of differentinfections detected from 75 to 123, or from 1.25 to 2.05 per individual. Thusthe first examination revealed 60.9 per cent of the infections found in 2.15examinations. In the home-service group the examinations of 25 cases, with atotal of 57 examinations, or 2.3 per individual, increased the number ofinfections detected in these cases from 47 to 93, or from 1.9 to 3.7 differentinfections per individual. In this group the first examinations revealed 50.5per cent of the infections found in 2.3 examinations per individual.
In view of the large percentage of cases in which it waspossible to make only one examination, it is highly probable that the totalpercentage of men infected among those examined is considerably higher than ourrecords indicate, particularly for protozoan infections.
There has been little, if any, selection of cases forexamination. The data represent the average run of the sick and wounded menreceived at Debarkation Hospital No. 3 from overseas, and of food handlers,etc., of the port. They were not, as a rule, dysenteric patients, though manyof the positives carrying cysts of Entamoba histolytica reported one ormore attacks of diarrhea or dysentery, in some cases with treatment, while onduty overseas.
TABLE 94.-Summary of infections by intestinal parasites in2,300 overseas troops and 576
home-service troops of the United States Army
CASES OF INFECTION
546
As shown in Table 94, the infected men (1,533 or 66.6 percent) were relatively more numerous in the overseas group than among those whohad only home service (345 or 59.9 per cent) and on computation it appears thatoverseas men averaged 1.2 infections by different parasites per man ascontrasted with 1.03 infections for men having home service only. These resultsindicate that many of the infections were presumably carried overseas and notacquired there in the first instance, although there is some evidence that manyoverseas men carried heavier infections than did home service troops. Indetermining the significance of this difference the source of the home servicetroops previously referred to should be considered. It may be that thepercentages of infections found among them were somewhat higher than they wouldhave been in the more representative troops on their departure overseas, andthat the infections acquired abroad were in reality more numerous than our datareveal.
An analysis of the data in the tabulation given aboveexhibits certain very significant features. In the first place the men withhookworm infections were all, with 13 exceptions, from the known areas ofhookworm occurrence in this country. There is thus slight indication of theacquisition of this infection overseas.
In the case of Trichuris trichiura, a differentcondition is found. In home service troops there were 14 infections, or 2.4 percent, while in the overseas troops there were 136 infections, or 5.9 per cent.In the home service troops seven of these infections were in recent immigrantsfrom Europe and two were in negroes from Florida. Deducting the number of theseimmigrants, the percentage of infection in the remaining falls from 2.4 to 1.2,but even this percentage is probably not representative of our troops ondeparture overseas. An examination of the stools of 145,016 men in the SouthernDepartment revealed only 162 cases of infection by Trichuris trichiura, or0.1 per cent. These were men mainly from Texas and Oklahoma, but representativesof every State in the Union were included. In a total of 501,472 examinationsreported to the Surgeon General there are 1,945 cases of Trichuris, or 0.38 percent.
HELMINTH INFECTIONS IN OVERSEAS AND HOME SERVICE TROOPS
The infections which are of significance have already beenreferred to in the discussion of fecal infection in overseas troops. A moredetailed account of the results of the examinations for helminths in the twogroups of soldiers will now be given.
A tabular summary of 437 examinations of home service menand 2,253 from overseas follows.
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TABLE 95.-Infections by hookworm and Hymenolepis nana in men fromNorthern States
State |
| Home service | ||||||||||
| Hymenolepis nana | Negative | Totals | Hookworm | Hymenolepis nana | Negative | Totals | |||||
| Per cent | Number | Per cent | Number | Per cent | Number | Per cent | |||||
Arizona | 1 | 16.7 | 0 | 0 | 5 | 6 | 0 | 0 | 0 | 0 | 1 | 1 |
California | 1 | 1.9 | 1 | 1.9 | 51 | 53 | 0 | 0 | 0 | 0 | 9 | 9 |
Colorado | 1 | 6.2 | 0 | 0 | 15 | 16 | 0 | 0 | 0 | 0 | 3 | 3 |
Connecticut | 0 | 0 | 0 | 0 | 33 | 33 | 0 | 0 | 0 | 0 | 4 | 4 |
Delaware | 0 | 0 | 0 | 0 | 2 | 2 | 0 | 0 | 0 | 0 | 2 | 2 |
Idaho | 0 | 0 | 0 | 0 | 7 | 7 | 0 | 0 | 0 | 0 | 1 | 1 |
Illinois | 0 | 0 | 1 | .7 | 140 | 141 | 0 | 0 | 0 | 0 | 18 | 18 |
Indiana | 0 | 0 | 0 | 0 | 61 | 61 | 0 | 0 | 0 | 0 | 10 | 10 |
Iowa | 0 | 0 | 0 | 0 | 55 | 55 | 0 | 0 | 0 | 0 | 3 | 3 |
Kansas | 0 | 0 | 0 | 0 | 43 | 43 | 0 | 0 | 0 | 0 | 2 | 2 |
Maine | 0 | 0 | 0 | 0 | 15 | 15 | 0 | 0 | 0 | 0 | 15 | 15 |
Massachusetts | 1 | 1.2 | 1 | 1.2 | 79 | 81 | 1 | 3.1 | 0 | 0 | 31 | 32 |
Michigan | 1 | 1.2 | 0 | 0 | 79 | 80 | 0 | 0 | 0 | 0 | 30 | 30 |
Minnesota | 1 | 1.3 | 0 | 0 | 73 | 74 | 0 | 0 | 0 | 0 | 8 | 8 |
Montana | 1 | 5.9 | 0 | 0 | 16 | 17 | 0 | 0 | 0 | 0 | 0 | 0 |
Nebraska | 0 | 0 | 0 | 0 | 11 | 11 | 0 | 0 | 0 | 0 | 2 | 2 |
Nevada | 0 | 0 | 0 | 0 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 |
New Hampshire | 1 | 9.1 | 0 | 0 | 10 | 11 | 0 | 0 | 0 | 0 | 5 | 5 |
New Jersey | 0 | 0 | 0 | 0 | 57 | 57 | 0 | 0 | 1 | 2.6 | 38 | 39 |
New York | 2 | .7 | 1 | .4 | 264 | 267 | 1 | 1.1 | 1 | 1.1 | 85 | 87 |
North Dakota | 0 | 0 | 0 | 0 | 9 | 9 | 0 | 0 | 0 | 0 | 2 | 2 |
Ohio | 1 | .8 | 0 | 0 | 122 | 123 | 0 | 0 | 0 | 0 | 12 | 12 |
Oregon | 1 | 5.9 | 0 | 0 | 16 | 17 | 0 | 0 | 0 | 0 | 2 | 2 |
Pennsylvania | 0 | 0 | 1 | .5 | 186 | 187 | 1 | 1.7 | 0 | 0 | 56 | 57 |
Rhode Island | 0 | 0 | 0 | 0 | 15 | 15 | 0 | 0 | 0 | 0 | 2 | 2 |
South Dakota | 0 | 0 | 0 | 0 | 9 | 9 | 0 | 0 | 0 | 0 | 1 | 1 |
Utah | 0 | 0 | 0 | 0 | 8 | 8 | 0 | 0 | 0 | 0 | 0 | 0 |
Vermont | 0 | 0 | 0 | 0 | 8 | 8 | 0 | 0 | 0 | 0 | 6 | 6 |
Washington | 0 | 0 | 0 | 0 | 29 | 29 | 0 | 0 | 0 | 0 | 3 | 3 |
Wisconsin | 1 | 1.7 | 0 | 0 | 58 | 59 | 0 | 0 | 0 | 0 | 17 | 17 |
Wyoming | 0 | 0 | 0 | 0 | 7 | 7 | 0 | 0 | 0 | 0 | 0 | 0 |
| 13 | .9 | 5 | .3 | 1,484 | 1,502 | 4 | 1.1 | 2 | .5 | 368 | 373 |
TABLE 96.-Infections by hookworm and Hymenolepis nana in men from Southern States
State |
| Home service | ||||||||||
| Hymenolepis nana | Negative | Totals | Hookworm | Hymenolepis nana | Negative | Totals | |||||
| Per cent | Number | Per cent | Number | Per cent | Number | Per cent | |||||
Alabama | 18 | 40.0 | 1 | 2.2 | 26 | 45 | 1 | 16.7 | 0 | 0 | 5 | 6 |
Arkansas | 4 | 11.8 | 0 | 0 | 30 | 34 | 0 | 0 | 0 | 0 | 3 | 3 |
Florida | 10 | 37 | 0 | 0 | 17 | 27 | 2 | 13.3 | 0 | 0 | 13 | 15 |
Georgia | 25 | 50 | 0 | 0 | 25 | 50 | 3 | 43.3 | 0 | 0 | 4 | 7 |
Kentucky | 10 | 18.2 | 0 | 0 | 45 | 55 | 0 | 0 | 0 | 0 | 4 | 4 |
Louisiana | 8 | 19.5 | 0 | 0 | 33 | 41 | 0 | 0 | 0 | 0 | 4 | 4 |
Maryland | 0 | 0 | 0 | 0 | 21 | 21 | 0 | 0 | 0 | 0 | 5 | 5 |
Mississippi | 6 | 17.1 | 0 | 0 | 29 | 35 | 0 | 0 | 0 | 0 | 0 | 0 |
Missouri | 0 | 0 | 0 | 0 | 78 | 78 | 0 | 0 | 0 | 0 | 5 | 5 |
New Mexico | 0 | 0 | 0 | 0 | 7 | 7 | 0 | 0 | 0 | 0 | 0 | 0 |
North Carolina | 13 | 26 | 0 | 0 | 37 | 50 | 2 | 40 | 1 | 20 | 2 | 5 |
Oklahoma | 6 | 11.5 | 1 | 1.9 | 45 | 52 | 0 | 0 | 0 | 0 | 0 | 1 |
South Carolina | 13 | 33.3 | 1 | 2.6 | 25 | 39 | 1 | 100 | 0 | 0 | 0 | 1 |
Tennessee | 10 | 22.2 | 0 | 0 | 35 | 45 | 1 | 100 | 0 | 0 | 0 | 1 |
Texas | 7 | 7.3 | 1 | 1 | 88 | 96 | 0 | 0 | 0 | 0 | 3 | 3 |
Virginia | 11 | 26.8 | 0 | 0 | 30 | 41 | 1 | 20 | 0 | 0 | 4 | 5 |
West Virginia | 1 | 3 | 1 | 3 | 33 | 35 | 1 | 33.3 | 0 | 0 | 2 | 3 |
| 142 | 18.8 | 5 | .6 | 604 | 751 | 12 | 18.5 | 1 | 1.5 | 51 | 64 |
548
As shown in the above tables, there were only 13 cases ofinfection by hookworm, or 0.9 per cent, among 1,502 men from Northern Statesfrom overseas, and 4 among 373 home service, or 1.1 per cent. In the case of 757men from the hookworm area, with overseas service, there were 142 infections, or18.8 per cent, while in 64 home-service men from that area there were 12, or 18.5 per cent. The differences between infections inhome-service men and overseas men by hookworm are not the probable error and donot show any clear evidence of any increase in the infection due to overseasexperiences. There is likewise no evidence that overseas men had an increasedinfection of Hymenolepis nana. In fact, among home-service men, largelyfood handlers, this infection was heavier than among overseas men, both amongthe northern and southern men.
In the case of infections by Trichuris trichiura, thecase is different. We have here an infection carried to new human hosts in theunhatched egg stage. The ova are discharged in an undeveloped stage, and do nothatch to a larva stage until taken into the digestive tract of man. Afterdischarge with the feces, the egg of Trichuris may live in moist earth or waterfor not less than five years under experimental control. Presumably at any timein this period, if taken into the digestive tract of man, it develops into theadult worm.
Whenever sanitary provisions for the proper care of humansewage are defective or imperfectly observed, wherever night soil is depositedin fields or gardens which drain into water supplies or near springs used fordrinking purposes, opportunities for infection may be afforded. Wherever flieshave access to freshly deposited or accumulated feces and at the same time tokitchens and mess halls, or food in any stage of its preparation prior tocooking, they may carry the ova on their feet from the feces to the food andthus infect it.
The degree of infection of any population or body of soldiersby whipworm is a measure of the effectiveness of the sanitary protection frominfection by organisms of human feces under which they have been living forseveral years prior to the examination. The same conclusions may be derived fromthe degree of infection by Ascaris lumbricoides for similar reasons.
The infection by these two helminths in the United Statesdoes not have a distribution similar to that by hookworm, but is affected by twodiverse factors: Immigration from the more highly infected regions in thesouth of Europe, and by sanitary conditions in the Appalachian Mountains region,especially in coal mining and cotton mill centers. Eastern Kentucky andTennessee and West Virginia appear to be centers of infection by these twohelminths.
The total number of infections by Trichuris and by Ascarisreported in all records compiled in this report were 1,862 and 3,013,respectively, for over 450,000 examinations, or 0.4 and 0.6 per cent,respectively. In the overseas men the total infections by these two helminthswere 136 and 26, or 5.9 and 1.1 per cent, respectively. This is a fifteenfoldincrease in the case of Trichuris in overseas men as compared with the body oftroops surveyed and a twofold measure in Ascaris. Since the southern men formedonly about one-third of the overseas men examined and made up the greater partof the surveyed before going overseas, it is highly probable that the increasein infections by these helminths as a result of the overseas service was inreality considerably
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greater than we have computed it to be. This increasedinfection by these helminths appears to have been the direct result of overseasservice, and to have been caused by fecal infections of food and water.
The presence of such carriers of amebic dysenteryconstitutes a menace to the health of armies in field operations, of troops incamps, and of the communities in which they may reside later, especially wheresanitation is neglected and the fly nuisance prevails. The number of cystsdischarged daily by a carrier of amebic dysentery varies greatly according tothe degree of infection. A moderately infected case of Entamoba histolytica waskept under daily observation and examination for 42 days and the whole stoolstirred to a uniform suspension and diluted to 500 and 1,000 c. c. in normalsalt solution. The numbers of cysts of Giardia, Entamoba histolytica, andE. coli were determined in the counting chamber of a hemocytometer andcomputed for the stool as a whole, with the result that E. histolytica cystswere found on 26 of the 42 days in numbers ranging from 330,000 to 45,000 perday, averaging 14,520,000 for the 26 days, or 8,145,000 for the whole period of42 days. Cysts of Giardia intestinalis were present on only 17 of the 42days in numbers varying from 5,000,000 to 3,625,000,000 per stool, and averaging925,200,000 per day. Entamoba coli was much rarer, being found in thiscase on only 3 of the 42 days, with an average of 3,110,000 cysts per day forthe 3 days. The margin of error in these computations is large, but after dueallowances are made for this, the number of cysts discharged by carriers isstill large enough to provide for a wide dispersal of the cysts by flies orother agents. The sizes of these cysts range from 5 to 20 microns in the main,most of them are from 7 to 15 microns in diameter, and are thus of such volumethat they could easily be carried on the foot of a fly. Computations show that100 to 150 of the larger cysts and 500 to 2,000 of the smaller ones could becrowded in the area of a fly's foot in a single layer.
The possibility that the carrier problem in the case ofamebic dysentery and other human protozoan infections is a much larger one thanhitherto recognized is raised by the data here presented. Furthermore, thefindings among home-service troops are indicative that the endemic area ofinfection by Entamoba histolytica in the United States is not confinedto the Southern States.
