548 THE ANIMAL PARASITES OF MAN 



The filaria embryos appear to circulate for a long time in the blood before 

 they produce symptoms. Gradually general malaise develops, also pain in the 

 small of the back and renal region, and in the scrotum, followed by an inter- 

 mittent hematochyluria. Fever and enlargement of the spleen often accom- 

 pany the symptoms. After continuing for days and weeks these phenomena 

 cease, to reappear at the end of a certain period. During the attack the urine 

 is of a peach-red color. Blood and blood coaguli are found in the sediment, 

 while the urine above this is turbid, whitish, and has a tint of yellow not 

 unlike diluted cream. Upon the surface a cream-like fatty layer may fre- 

 quently be noticed. Sugar and peptone are absent; cholesterin, lecithin, 

 neutral fats, and fatty acids are present. Besides the embryos, red and white 

 corpuscles and large and small fat globules are found. Gradually the lymph- 

 glands enlarge, in the males the scrotum, in the female the labia. The symp- 

 toms disappear, to return in a short time in an exaggerated form. Elephan- 

 tiasis-like swellings form upon the lower, and later upon the upper, extremities. 

 The disease finally causes death, after running a course for years with the 

 symptoms of marasmus. 



Whether recovery, which occasionally is spontaneous, is due to remedies 

 or not is very questionable. Drugs appear to have no influence upon the para- 

 site. Surgical interference has been frequently attempted, but, according to 

 Scheube, does not prevent relapses. The utmost stress is to be laid upon 

 prophylaxis, and in this the question of drinking-water is of special impor- 

 tance. The habit of drinking unfiltered water from ditches and cisterns in 

 the tropics is undoubtedly a cause of the distribution of the parasite. Physi- 

 cians living in these regions strenuously advise that only filtered water, or 

 drinking-water from closed conduits, be used. 



It is evident that our knowledge of filariasis is far from complete, and it 

 is hoped that future investigations may shed light upon some of its dark prob- 

 lems. For example, John O'Neill observed a filaria which produced prurigi- 

 nous vesicles and nodules upon the fingers and elbows with severe itching, and 

 of this parasite nothing further has been heard. 



Among the most frequent human parasites are the ascaris lumbricoides, 

 Linne, 1758, trichocephalus dispar, Eudolphi, 1801, and the oxyuris vermicu- 

 laris, Linne, 1767. 



A zoologic description of these parasites is unnecessary as they are well 

 known. 



The ascaris lumbricoides resembles the rain-worm, and is unquestionably 

 the most common parasite of man. Its embryology was first clearly described 

 by Grassi in the year 1887, and he proved that it does not require an inter- 

 mediary host. The fact of direct infection with embryo-containing ova has 

 been confirmed by the further investigations of Lutz and Epstein. 



Besides the ascaris lumbricoides, the ascaris mystax, Zeder (the nematode 

 of the cat or dog), has also been occasionally found in man. This parasite 

 is much smaller than that of man; and upon the end containing the head 

 two wing-like processes are situated which at once distinguish this worm from 

 those mentioned above. 



