[Relationship between the sex of Schistosoma japonicum and circulating antigen detection].

Single sex cercariae were used to infect rabbits and the detection of circulating membrane antigen by dot-ELISA were followed up until 1 year postinfection. 9 rabbits infected with male cercariae (worm recovery 15-133, mean 53.1) and 9 rabbits infected with female cercariae (worm recovery 1-102, mean 39.1) were examined but no positive reaction was occurred. On the contrary, 7 rabbits infected with bi-sex cercariae (worm recovery 4-161, mean 67.1) all showed positive reactions 6-10 wks post-infection. Uni-sex female worms usually could not develop to maturity within rabbits even 1 year after infection, suggesting that the life-span of uni-sex female worm might be 1 year at least in rabbits. The uni-sex male worms could develop to maturity, being usually stout. The question why no circulating membrane antigen (even CCA, unpublished data) could be detected and the nature of antigen we detected needs further investigation.