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Memórias do Instituto Oswaldo Cruz
Fundação Oswaldo Cruz, Fiocruz
ISSN: 1678-8060
EISSN: 1678-8060
Vol. 92, No. 3, 1997, pp. 323-328
Bioline Code: oc97060
Full paper language: English
Document type: Research Article
Document available free of charge

Memórias do Instituto Oswaldo Cruz, Vol. 92, No. 3, 1997, pp. 323-328

 en Evaluation of chemical and physical-morphological factors as potential determinants of Biomphalaria pfeifferi(Krauss, 1848) distribution
Jurg Utzinger; Charles Mayombana; Konstanze Mez & Marcel Tanner

Abstract

This study was carried out in five sites along a small perennial river
system in south-central Tanzania, which had been identified as the focus
for transmission of intestinal schistosomiasis in the area. Malacological
surveys preceding the study showed a focal distribution of Biomphalaria
pfeifferi, intermediate host snail of Schistosoma mansoni, the snails being
present in three sites but absent from the other two sites. The objective
of this study was to evaluate to what extent chemical and/or
physical-morphological factors determine the distribution of B. pfeifferi
between these five sites. 

It was found that none of the chemical constituents in the waters examined were outside the tolerance range of B. pfeifferi snails. Moreover, the composition of water from B. pfeifferi-free sites was not different from that in those sites where snails occurred. Furthermore, none of the physical-morphological constituents seemed likely to be a determinant for the absence of B. pfeifferi.

In view of these findings, and those of previous studies, it is concluded that the focal distribution of B. pfeifferi cannot be associated with a single environmental factor and is rather the result of more complex interactions of habitat factors.

Keywords
Biomphalaria pfeifferi - physical-morphological factors - schistosomiasis - Tanzania - water chemistry

 
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