Hepatic fibrosis in Schistosoma haematobium-infected mice.

Swiss mice were exposed subcutaneously to 270 to 500 Schistosoma haematobium cercariae and killed 13 to 52 weeks later. Less than 10% of applied cercariae were recovered as worms, and the rate of oviposition by adult worm pairs was generally low. However, the adult worms survived well, the females contained an average of 56 eggs one year after infection, and numerous mature eggs were present in the tissues. All worms were located in the portal venous system. S. haematobium eggs in the liver elicited marked fibrosis, comparable to the fibrosis induced by S. mansoni infection. Only minimal fibrosis is seen around S. haematobium eggs in the liver of numerous other species, including man, the chimpanzee, other non-human primates and hamsters. Our findings illustrate the diverse relationships often seen between a single schistosome species and its mammalian hosts and emphasize the uncertainty in predicting the outcome of human schistosome infections from the study of experimental hosts.