FIG. 1.

Stage-specific susceptibility of S. mansoni to praziquantel (•), oxamniquine (○), and artemether (▪). Details of the original experiments are provided elsewhere (58, 82). In brief, mice were infected with S. mansoni cercariae and treated orally with an antischistosomal drug (for praziquantel, three doses of 250 mg/kg on alternate days; for oxamniquine, a single dose of 50 mg/kg; for artemether, a single dose of 400 mg/kg) at different time points postinfection (e.g., on days 0, 7, 14, 21, 28, 35, and 42 in the case of praziquantel). Schistosomes were recovered 4 weeks posttreatment. Mean worm burden reductions were calculated by comparison of mean worm burdens in the treatment groups with those from a group of control mice that were also infected with S. mansoni but that remained untreated. It is noteworthy that oviposition is only reached 34 to 35 days after infection (14).