BLOOD FLUKES 



213 



Blood Flukes 



The most important flukes parasitic in man are three species 

 of Schistosoma (or Bilharzia) which live in the large bloodvessels 

 of the abdominal cavity. 



Schistosoma is one of the few genera of flukes in which the sexes 

 are separate. The relation of the sexes is one of the most remark- 

 able in nature. The mature 

 male worm (Fig. 64) has a 

 cylindrical appearance due to 

 the fact that the sides of the 

 flat body are folded over to 

 form a ventral groove In this 

 groove, projecting free at each 

 end but enclosed in the middle, 

 is the longer and slenderer fe- 

 male, safe in the arms of her 

 lord. While young the sexes 

 live apart, but as soon as sex- 

 ual maturity is attained they 

 couple together and spend the 

 rest of their lives in this man- 

 ner. 



Unlike the liver flukes, the 

 blood flukes do not develop 

 great numbers of eggs all at 



Once, but instead develop them FIG. 64. Blood fluke, Schistosoma hama- 



one by one and have only a iobium >' male ( $ ) carrying female ( 9 ) in 



r . * ventral groove; int., intestine; gyn. c., 



I6W in the OVldUCt at any One gynecophoric canal or ventral groove; m., 



time. Such a method of re- f outl \ ; v - s - ventral sucker - x 8. (After 



Looss.) 



production is facilitated, of 



course, by the constant juxtaposition of the male and female 

 worms. The blood flukes live correspondingly much longer than 

 the liver flukes, often persisting for many years. 



Schistosoma haematobium. The most important species 

 from the pathogenic point of view is Schistosoma hcematobium 

 (Fig. 64). This parasite is common in the countries surrounding 

 the eastern end of the Mediterranean, southern Asia and many 

 parts of Africa, especially the east coast. In Egypt over half 



