Hepatosplenic schistosomiasis mansoni and japonica compared in mice each infected with one pair of worms

The severity of hepatosplenic schistosomiasis mansoni and japonica was compared in mice each infected with only one pair of worms. 8, 10 and 12 weeks after exposure the mice infected with S. japonicum had a greater fall in body weight, and increase in liver weight, spleen weight and portal pressure than those infected with S. mansoni. In addition they had a fall in haematocrit and serum albumin concentration and a much greater rise in serum globulin concentration. Egg counts revealed that animals with one pair of S. japonicum had almost 10 times as many eggs in their livers as those with one pair of S. mansoni. Under uniform conditions in the murine host, therefore, schistosomiasis japonica is unquestionably a more severe disease than schistosomiasis mansoni, and the primary factor in its greater virulence appears to be the greater egg production of S. japonicum.