Antischistosomal effect of cyclosporin A: cure and prevention of mouse and rat schistosomiasis mansoni.

C57BL/6 mice infected with Schistosoma mansoni at day 0 and injected with cyclosporin A (CyA) either daily or from day -1 to day 3 were protected against schistosomiasis mansoni as indicated by a decrease in the number of worms recovered from the liver 45 days after infection. CyA treatment also protected rats and strains of mice with known immunity defects (nu/nu, P/N, CBA/N). Protection was evident against both primary and secondary infection in mice infected at day 0, reinfected at day 42, and treated daily with CyA either during the course of the experiment or only from day -1 to day 3, as indicated by the worm burden at day 67. In such an experiment of infection and reinfection, the immature worms were shown to be the target of CyA. Administration of the drug 27, 45, 62, or 100 days before infection confirmed the long-term protective effect of CyA. This drug did not evoke the killing of adult worms in vivo. These data confirm and define the curative and preventive effect of CyA against schistosomiasis mansoni.