title: Distribution patterns and cercarial shedding of Bulinus nasutus and other snails in the Msambweni area, Coast Province, Kenya.
abstract: In the Msambweni area of the Kwale District in Kenya, an area endemic for Schistosoma haematobium, potential intermediate-host snails were systematically surveyed in water bodies associated with human contact that were previously surveyed in the 1980s. Bulinus (africanus) nasutus, which accounted for 67% of the snails collected, was the only snail shedding S. haematobium cercariae. Lanistes purpureus was the second most common snail (25%); lower numbers of Bulinus forskalii and Melanoides tuberculata were also recovered. Infection with non-S. haematobium trematodes was found among all snail species. Rainfall was significantly associated with the temporal distribution of all snail species: high numbers of Bulinus nasutus developed after extensive rainfall, followed, in turn, by increased S. haematobium shedding. Spatial distribution of snails was significantly clustered over a range of up to 1 km, with peak clustering observed at a distance of 400 meters. Water lily (Nymphaea spp.) and several aquatic grass species appeared necessary for local colonization by B. nasutus or L. purpureus.
authors.affiliation: Division of Vector Borne Diseases, Ministry of Health, Nairobi, Kenya.
authors.forename: H Curtis
authors.initials: HC
authors.lastname: Kariuki
authors.forename: Julie A
authors.initials: JA
authors.lastname: Clennon
authors.forename: Melinda S
authors.initials: MS
authors.lastname: Brady
authors.forename: Uriel
authors.initials: U
authors.lastname: Kitron
authors.forename: Robert F
authors.initials: RF
authors.lastname: Sturrock
authors.forename: John H
authors.initials: JH
authors.lastname: Ouma
authors.forename: Saidi Tosha Malick
authors.initials: ST
authors.lastname: Ndzovu
authors.forename: Peter
authors.initials: P
authors.lastname: Mungai
authors.forename: Orit
authors.initials: O
authors.lastname: Hoffman
authors.forename: Joseph
authors.initials: J
authors.lastname: Hamburger
authors.forename: Cara
authors.initials: C
authors.lastname: Pellegrini
authors.forename: Eric M
authors.initials: EM
authors.lastname: Muchiri
authors.forename: Charles H
authors.initials: CH
authors.lastname: King
mesh_terms: D000818:Animals; D002033:Bulinus / Q000254:growth & development* / Q000469:parasitology*; D016000:Cluster Analysis; D004199:Disease Vectors; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007630:Kenya; D017215:Satellite Communications; D012548:Schistosoma haematobium / Q000254:growth & development*; D012553:Schistosomiasis haematobia / Q000469:parasitology / Q000635:transmission*; D014867:Water / Q000737:chemistry / Q000469:parasitology*
chemical_list: D014867:Water