SCHISTOSOMA ILEMATOBIUM 213 



From this symptom the disease caused by infection with Schis- 

 tosoma hcematobium is often called " parasitic hsematuria." Ex- 

 cept in severe infections no serious symptoms appear, but when 

 numerous the worms cause much pain and give rise to a great 

 variety 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 in 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 

 people. It is reported that of 625 British soldiers who became 



B 



FIG. 66. Egyptian snails which serve as intermediate hosts for blood flukes; A, 

 Bullinus contortus, an intermediate host for Schistosoma hcematobium; B, Planorbis 

 boissyi, an intermediate host for Schistosoma mansoni. (After Leiper.) 



infected with blood flukes in South Africa during the Boer war, 

 359 were still on the sick list in 1914 exclusive of those perma- 

 nently pensioned. The cost to the British government for per- 

 manent and " conditional " pensions for these soldiers amounted 

 to nearly $54,000 a year. 



The life history of Schistosoma hcematobium has only recently 

 been worked out by Leiper, of the British Army Medical Corps, 

 in Egypt. It was long known that a ciliated embryo or mira- 

 cidium developed inside the egg shells, even before they left the 

 body of the host, and that these embryos hatched out and swam 

 about when the eggs were immersed in water, but beyond this 

 point the life history could only be conjectured from analogy with 

 the liver fluke. Leiper, who had already made some investi- 

 gations in regard to the life history of S. japonicum in China, 



