Curative chemotherapy and resistance to reinfection in murine schistosomiasis.

Complete parasitological cure was obtained by specific chemotherapy in mice with a 10-week-old infection induced by inoculating 30 cercariae of Schistosoma mansoni. By challenging the cured animals with 100 cercariae it was found that cutaneous and pulmonary reactivity to invading schistosomula, the ability to modulate periovular granulomas in the liver, and the resistance to reinfection, as measured by survival rates and recovery of worms from the portal vein system, persisted for 1 and 2 months following treatment and disappeared after 6 months. Thus, a residual immunity and reactivity to reinfection seems to persist in the host for some time after curative chemotherapy of schistosomiasis.