WORM DEVELOPMENT IN HAMSTERS INFECTED WITH UNISEX AND CROSS-MATED SCHISTOSOMA-MANSONI AND SCHISTOSOMA-HAEMATOBIUM

Schistosoma mansoni and Schistosoma haematobium coexist in Egypt and i n other areas in Africa, and people frequently are infected with paras ites of both species. The effects of the interactions between worms of both sexes of the 2 species on development and egg laying were evalua ted in vivo by infecting hamsters with cercariae from Biomphalaria ale xandrina and Bulinus truncatus snails infected with single miracidia. In hamsters with unisex infections, male worms of both species were sm all. Schistosoma mansoni females were stunted and partially mature but did not contain eggs. Schistosoma haematobium females, though stunted , sometimes contained and laid small eggs, which were deposited in the liver, but few of which contained motile embryos. This suggests that unisexual infection with S. haematobium female worms produces a risk f or liver damage due to egg deposition in tissues. Both S. mansoni and S. haematobium females that mated with males of the heterologous speci es were significantly larger than females from unisexual infections; t hey were sexually mature and possessed eggs in the uterus. The eggs in the liver homogenates of cross-specific infected hamsters contained f ully developed miracidia that hatched in filtered pond water.