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Memórias do Instituto Oswaldo Cruz
Fundação Oswaldo Cruz, Fiocruz
ISSN: 1678-8060
EISSN: 1678-8060
Vol. 95, No. 3, 2000, pp. 287-294
Bioline Code: oc00050
Full paper language: English
Document type: Research Article
Document available free of charge

Memórias do Instituto Oswaldo Cruz, Vol. 95, No. 3, 2000, pp. 287-294

 en Microhabitat Preferences of Biomphalaria pfeifferi and Lymnaea natalensis in a Natural and a Man-made Habitat in Southeastern Tanzania
Jrg Utzinger & Marcel Tanner


Schistosoma mansoni check for this species in other resources is an important human parasitic disease which is widespread throughout Africa. As Biomphalaria pfeifferi check for this species in other resources snails act as intermediate host, knowledge of their population ecology is an essential prerequisite towards understanding disease transmission. We conducted a field study and assessed the density and microhabitat preferences of B. pfeifferi in a natural habitat which was a residual pool of a river. Repeated removal collecting revealed a density of 26.6 [95% confidence interval (CI): 24.9-28.3] snails/m2. B. pfeifferi showed microhabitat preferences for shallow water (depths: 0-4 cm). They were found most abundantly close to the shoreline (distances: 0-40 cm), and preferred either plant detritus or bedrock as substratum. Lymnaea natalensis check for this species in other resources , a snail which may act as a host for human Fasciola gigantica, also occurred in this habitat with a density of 34.0 (95% CI: 24.7-43.3) snails/m2, and preferred significantly different microhabitats when compared to B. pfeifferi. Microhabitat selection by these snail species was also investigated in a man-made habitat nearby, which consisted of a flat layer of concrete fixed on the riverbed, covered by algae. Here, B. pfeifferi showed no preference for locations close to the shoreline, probably because the habitat had a uniform depth. We conclude that repeated removal collecting in shallow habitats provides reliable estimates of snail densities and that habitat changes through constructions may create favourable microhabitats and contribute to additional disease transmission.

Biomphalaria pfeifferi, Lymnaea natalensis, man-made habitat, microhabitat preferences, removal collecting, schistosomiasis, Tanzania

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