Parasitology

Research Article

The development and validation of an age-structured model for the evaluation of disease control strategies for intestinal helminths

M. S. Chana1 p1, H. L. Guyatta2, D. A. P. Bundya1 p1 and G. F. Medleya3

a1 WHO Collaborating Centre for the Epidemiology of Intestinal Parasitic Infections, Department of Biology, ImperialCollege, London SW7 2BB, UK

a2 Swiss Tropical Institute, Socinstrasse 57, CH 4002 Basel, Switzerland

a3 Analysis and Management Group, Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK

Abstract

Epidemiological modelling can be a useful tool for the evaluation of parasite control strategies. An age-structured epidemiological model of intestinal helminth dynamics is developed. This model includes the explicit representation of changing worm distributions between hosts as a result of treatment, and estimates the morbidity due to heavy infections. The model is used to evaluate the effectiveness of different programmes of age-targeted community chemotherapy in reducing the amount of morbidity due to helminth infection. The magnitude of age-related heterogeneities is found to be very important in determining the results of age-targeted treatment programmes. The model was verified using field data from control programmes for Ascaris lumbricoides and Trichuris trichiura, and was found to provide accurate predictions of prevalence and mean intensities of infection during and following different control regimes.

(Received October 16 1993)

(Revised February 12 1994)

(Accepted February 12 1994)

Correspondence:

p1 Present address: Department of Zoology, University of Oxford, South Parks Road, Oxford OXI 3PS.

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