Reduced reproductive efficiency in mice with schistosomiasis mansoni and in uninfected pregnant mice injected with antibodies against Schistosoma mansoni soluble egg antigens.
Female CBA/J mice were infected with approximately 15 cercariae of Schistosoma mansoni and mated with normal syngeneic males 7 weeks later. Uninfected mice were bred in parallel, and both groups were subsequently bred several more times. Pregnancies were documented by formation of vaginal plugs, and daily records were kept concerning the status of the pregnancies, delivery, and offspring. One hundred thirty-two pregnancies in uninfected mice resulted in 101 (77%) viable litters. In contrast, 133 pregnancies in mice infected with S. mansoni lead to 45 (34%) viable litters. The decreased number of viable litters born or raised by infected mothers resulted from maternal death during pregnancy (5%), spontaneous abortion (20%), and infanticide (42%). Observations of multiparous infected mice indicated that this reduced rate of production of viable, surviving offspring was not different in subsequent pregnancies nor influenced by the duration of the infection. At 2 weeks of age, offspring of infected mice weighed significantly less than offspring of equal-sized litters from uninfected mice, but this weight differential was not sustained beyond 2 weeks of age. Subsequent studies compared the effects on uninfected pregnant mice of injections of antibodies against S. mansoni soluble egg antigens (immunoaffinity-purified from sera of mice with 16 week S. mansoni infections) vs. normal mouse immunoglobulin. After repeated injections of these antibodies during multiple pregnancies, lowered reproductive efficiencies (37%) were observed as compared to parallel studies of pregnant mice injected with normal mouse immunoglobulin (67%).