Repeated Infection and Treatment of Mice with Schistosoma mansoni: Functional, Anatomic and Immunologic Observations

Abstract

Summary Mice were subjected to three courses of Schistosoma mansoni infection and subsequent stibophen treatment. Mice treated before or immediately after the onset of egg deposition showed little increase in portal pressure, liver size or spleen size. When treatment was withheld until four weeks after oviposition had begun, portal hypertension and hepatosplenomegaly appeared and were rapidly reversed following treatment. No immunity was detected after challenge of previously infected and treated mice. Worm burdens and hepatic egg counts were similar to those in mice infected for the first time. Hepatic response to dead worms and to eggs was similar in simultaneously exposed animals experiencing their first and third infections. Hepatic scars related to eggs and dead worms persisted in decreasing numbers until termination of the experiment more than a year after the last treatment. Dead worm lesions in the mice were focal, peripheral and predominantly intravascular. They did not appear to be histologically similar to the portal pipestem fibrosis seen in livers of humans with severe hepatosplenic schistosomiasis.