214 



THE FLUKES 



the population is said to be infected, and in an examination of 

 54 boys in the village of El Marg, near Cairo, 49 were found 

 infected. 



These flukes, about one-half inch in length, abound sometimes 

 in hundreds in the abdominal veins of their host, living especially 

 in the portal vein and its various branches. The eggs of the 

 worms, which are oval with a stout spine at one end (Fig. 65 A), 

 and about 0.16 mm. ( T ^ of an inch) long, are carried to the small 

 vessels on the surface of the urinary bladder. By means of the 

 sharp spine they penetrate to the wall of the bladder and are 

 voided with the urine. As the eggs enter the bladder they cause 

 a certain amount of bleeding, resulting in a bloody urine. From 

 this symptom the disease caused by infection with Schistosoma 

 hcematobium is often called " parasitic hsematuria." Except 



FIG. 65. Eggs of Schistoma; A, terminal spined egg on S. Hcematobium from 

 urine; B, lateral spined egg of S. mansoni from faeces; C, egg of S.japonicum, with 

 only rudiment of spine; note developed embryos in all. X about 200. (A and B 

 after Looss, C after Leiper.) 



in severe infections no serious symptoms appear, but when nu- 

 merous the worms cause much pain and give rise to a great va- 

 riety of abnormal conditions of the bladder. The damage they 

 do is partly the result of blocking of the veins, and partly the 

 result of inflammation and bleeding of the bladder caused by its 

 penetration by the spined eggs. Sometimes the kidneys, ureters 

 and other urino-genital organs are attacked and seriously affected. 

 In addition there can be little doubt but that the worms excrete 

 poisonous matter into the blood, as practically all parasitic worms 

 do to some extent, and this probably accounts for part at least 

 of the anemic and debilitated condition so common in infected 



