title: Reduction in transmission of Schistosoma mansoni by a four-year focal mollusciciding programme against Biomphalaria glabrata in Saint Lucia.
abstract: The effect of transmission of Schistosoma mansoni of a focal snail control programme was investigated over four years amongst approximately 1250 people living in five communities in the steep-sided Soufriere river valley, St. Lucia, West Indies. Bayer 6076 was applied from constant flow drip cans to 12 stream sections at a target dose of 8 mg/litre clonitralide every four weeks. Only proven and potential transmission sites were treated; marsh habitats, where Biomphalaria glabrata were widespread, were ignored. In the stream snail numbers were reduced by 94% in the first year and by 100% thereafter. Incidence of new S. mansoni infections amongst children fell from 18% in the last year before control to 6% and 9% after three and four years respectively. Amongst children and adults in the four years of control the conversion/reversion ratio declined leading to a lowering of the over-all prevalence from 40% to 22%. Parasitologically the results were similar to those of a previously evaluated area-wide mollusciciding programme. The mean annual cost per person protected was US $2.60. This figure is atypically high because the topography of the area severely limited the population size.
mesh_terms: D000293:Adolescent; D000328:Adult; D001700:Biomphalaria / Q000469:parasitology / Q000502:physiology; D002648:Child; D002675:Child, Preschool; D003365:Costs and Cost Analysis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008975:Molluscacides; D009534:Niclosamide / Q000031:analogs & derivatives; D010571:Pest Control / Q000191:economics / Q000379:methods; D011159:Population Surveillance; D012550:Schistosoma mansoni; D012552:Schistosomiasis / Q000453:epidemiology / Q000635:transmission*; D014900:West Indies
chemical_list: D008975:Molluscacides; D009534:Niclosamide