Dynamics of schistosoma haematobium infection in a Gambian community. II. The effect on transmission of the control of Bulinus senegalensis by the use of niclosamide.

Niclosamide was used to interrupt transmission of Schistosoma haematobium by Bulinus senegalensis in seasonal rainwater pools for a period of three years. Snail populations were progressively reduced to approximately 1% of the numbers in untreated pools. There was little or no evidence of acquisition of new infection by children in the area during the period of intervention. The intensity of infection in a cohort of children initially under 10 years old followed for three years fell by more than 50%, while there was a ten-fold increase in a similar group in a nearby untreated area. The mean annual cost (1982) of control per head of the population protected was pound 0.50 (US $0.89).