Compares the cost-effectiveness of three strategies for controlling the incidence of schistosomiasis, a parasitic disease transmitted by snails. The analysis was prepared from data obtained in a socioeconomic study of schistosomiasis conducted by A.I.D. in Tanzania, and utilizes the transmission model specified in that study's preliminary report. The effectiveness of the strategies (mollusciciding, chemotherapy, and mollusciciding plus chemotherapy) is rated in terms of case years of infection prevented. For each approach, costs are calculated and a cost-per-case-year-of-infection-prevented is developed. It is pointed out that this study does not address the possibility of controlling water supplies to limit human contact with snail habitats. Future research on such strategies is recommended. The report includes tables comparing results of the three control methods; chronologies of control activities are appended.