Distribution patterns and cercarial shedding of Bulinus nasutus and other snails in the Msambweni area, Coast Province, Kenya.
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.
Kariuki
H Curtis
HC
Division of Vector Borne Diseases, Ministry of Health, Nairobi, Kenya.
Clennon
Julie A
JA
Brady
Melinda S
MS
Kitron
Uriel
U
Sturrock
Robert F
RF
Ouma
John H
JH
Ndzovu
Saidi Tosha Malick
ST
Mungai
Peter
P
Hoffman
Orit
O
Hamburger
Joseph
J
Pellegrini
Cara
C
Muchiri
Eric M
EM
King
Charles H
CH
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*
D014867:Water