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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

Published online by Cambridge University Press:  01 August 2002

S. MORAND
Affiliation:
Laboratoire de Biologie Animale (UMR 5555 CNRS), Centre de Biologie et d'Ecologie Tropicale et Méditerranéenne, Université de Perpignan, 66860 Perpignan Cedex France
V. R. SOUTHGATE
Affiliation:
Biomedical Sciences Theme, Department of Zoology, The Natural History Museum, Cromwell Road, South Kensington, London SW7 5BD, UK
J. JOURDANE
Affiliation:
Laboratoire de Biologie Animale (UMR 5555 CNRS), Centre de Biologie et d'Ecologie Tropicale et Méditerranéenne, Université de Perpignan, 66860 Perpignan Cedex France

Abstract

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.

Type
Research Article
Copyright
© 2002 Cambridge University Press

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