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A model to explain the replacement of Schistosoma intercalatum by Schistosoma haematobium and the hybrid S. intercalatum × S. haematobium in areas of sympatry

2002; Cambridge University Press; Volume: 124; Issue: 4 Linguagem: Inglês

10.1017/s0031182001001342

1469-8161

Sergé Morand, V. R. Southgate, J. Jourdane,

Helminth infection and control

Numerous hypotheses have been postulated to explain the rapidly changing parasitological situation in Loum, Cameroon as a result of the interaction between Schistosoma haematobium and S. intercalatum . The aim of this study is to test the various hypotheses using a simple mathematical model, incorporating equal and unequal sex ratios of adult schistosomes, recombinations, and levels of compatibility with the intermediate molluscan hosts, B. forskalii and B. truncatus . The model assuming an equal sex ratio does not fit with the existing field data in that it predicts a continued presence of S. intercalatum, S. haematobium and the hybrids. The model assuming a sex bias in favour of males, which reflects the situation usually observed in schistosome populations, predicts the loss S. intercalatum which indeed concurs with the most recent data.