562 THE ANIMAL PARASITES OF MAN 



to six weeks after infection has taken place the first ova appear in the human 

 dejecta. 



The parasites, as well as the symptoms which are included under the name 

 ankylostomiasis, have been found exclusively in those persons who labor in 

 any way in the earth; miners, tunnel workmen, brickmakers, laborers upon 

 fortifications, etc. The dejecta voided by an ankylostoma host are exceed- 

 ingly rich in ova, as shown by the interesting observations of Leichtenstern 

 in the brick fields of Cologne, and they are the source of infection for other 

 workmen. The fecal masses deposited in the outskirts of the brick fields, with 

 the gradual advance of the work contaminate the layers of clay and become 

 mixed with the water. Thus there is abundant opportunity for the importa- 

 tion of encysted larvae. The workmen eat their meals with dirty clay-cov- 

 ered hands, and in their various manipulations of the clay and earthworks, 

 in cleaning their tools, in the use of drinking-water and water for other pur- 

 poses, there are numerous opportunities for the encysted ankylostoma to find 

 their way into the human organism. Miners and tunnel laborers, and espe- 

 cially the country population in Egypt, Brazil and other countries, infect 

 themselves in a similar manner. In the country, particularly, with its limi- 

 tations and the absence of systematic h3'giene, there are numerous favorable 

 conditions for the propagation of the parasites. In a damp, flat country 

 where the earth is only slightly permeable and there is an absence of suitable 

 latrines, discharge of the dejecta filled with ova in the immediate vicinity of 

 laborers and living places must, under any circumstances, convey the germs to 

 the inhabitants and laborers. Loos recently called attention to the fact that 

 the young embryo may enter the human organism by means of the skin. 



The number of parasites is frequently very great : One hundred, 500, 1,000 

 and more have been found in the small intestine. They are blood-suckers, 

 Kar iioxnv; and when we consider that their duration of life is. relatively 

 long— Leichtenstern estimates the maximum at five years — and that repeated 

 infection in one and the same individual in infected regions is probably the 

 rule, we can clearly understand the effects of this parasite, which is a blood- 

 sucker. 



Three to four weeks after infection the first symptoms appear. Besides 

 dyspeptic difficulties, these consist especially of colic, diarrhea, increasing 

 lassitude, disinclination to work, pallor of the face. Tinnitus aurium, ver- 

 tigo and cardiac palpitation are added. The continuous withdrawal of blood 

 in the course of weeks or months leads gradually to the most extreme symp- 

 toms of anemia. Edema, dyspnea, and attacks of syncope develop upon the 

 shghtest bodily exertion. The dejecta, often even five to six weeks after infec- 

 tion, have a hemorrhagic appearance ; they are grayish red, brownish red or 

 black. Usually the first hemorrhagic' diarrheic discharges occur from five to 

 six weeks after invasion of the larvae; during a time, therefore, in which the 

 parasites frequently change their situation for the purpose of copulation. In 

 the later course of the affection symptoms of extreme anemia develop in the 

 patients who have become bedridden. 



The pulse is rapid and thready. The carotids show active pulsation. In 

 the heart, which is frequently enlarged to percussion, there are systolic mur- 



