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Computer model of the maintenance and selection of genetic heterogeneity in polygamous helminths

Published online by Cambridge University Press:  06 April 2009

A. Saul
A. Saul
Affiliation:
Tropical Health Program, Queensland Institute of Medical Research, Royal Brisbane Hospital, Brisbane, Queensland, Australia4029
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Summary

A stochastic simulation model of the transmission and maintenance of genetic heterogeneity in the absence and presence of external selection pressures is presented for polygamous intestinal helminths such as Ascaris. The model assumes that the density distribution of the adult parasites is highly aggregated and that density-dependent effects on fecundity are important. The model gives rise to stable infection rates in the host. Where the parasite population contains genetic heterogeneity, with the exception of stochastic fluctuations which models genetic drift, the ratio of the different alleles remained constant over extended periods of time. This result contrasts with that of an earlier analytical model (Anderson, R. M., May, M. R. & Gutpa S. (1989) Parasitology 99, S59–S79), in which uneven mating probabilities for the different combinations of worm possible in a host was postulated to inevitably lead to fixation of the most abundant allele. New results suggest that in spite of the restricted choice of mating available to a worm in the confines of a host, selection pressure always leads to enrichment of the parasites carrying resistant alleles.

Keywords

mathematical modelsstochastic processeshelminthschemotherapygenetic heterogeneity
Type
Research Article
Information
Parasitology , Volume 111 , Issue 4 , November 1995 , pp. 531 - 536
Copyright
Copyright © Cambridge University Press 1995

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References

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