On the distribution of schistosome infections among host snails.
The distribution of Schistosoma haematobium infections in a population of Bulinus globosus snails collected from a field site in Zimbabwe is described. Cercariae of both sexes emerged from a proportion of patent infected snails, as was demonstrated by the detection of paired schistosomes in hamsters each exposed to cercariae from a single snail. These snails must have been infected by two or more miracidia. Analysis showed that the proportion of mixed-sex infections was higher than expected if infections were distributed at random among snails. An index of overdispersion was calculated. Overdispersion of infections results from heterogeneities in the exposure and/or susceptibility of snails to infection. The implications for the epidemiology and control of schistosomiasis haematobium are discussed.
Woolhouse
M E
ME
Department of Pure and Applied Biology, Imperial College, London SW7 2BB, U.K.
Chandiwana
S K
SK
Bradley
M
M
D000818:Animals; D002033:Bulinus / Q000469:parasitology*; D004199:Disease Vectors; D005260:Female; D008297:Male; D012548:Schistosoma haematobium / Q000502:physiology*; D015030:Zimbabwe