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Frequency distribution of Brugia malayi microfilariae in human populations

Published online by Cambridge University Press:  06 April 2009

A. Srividya
Affiliation:
Vector Control Research Centre, Medical Complex, Indira Nagar, Pondicherry–605 006, India
K. Krishnamoorthy
Affiliation:
Vector Control Research Centre, Medical Complex, Indira Nagar, Pondicherry–605 006, India
S. Sabesan
Affiliation:
Vector Control Research Centre, Medical Complex, Indira Nagar, Pondicherry–605 006, India
K. N. Panicker
Affiliation:
Vector Control Research Centre, Medical Complex, Indira Nagar, Pondicherry–605 006, India
B. T. Grenfell
Affiliation:
Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ
D. A. P. Bundy
Affiliation:
Wellcome Trust Research Centre for Parasitic Infection, Department of Biology, Imperial College, London SW7 2BB

Summary

This study examines the effects of host age and sex on the frequency distribution of Brugia malayi infections in the human host. Microfilarial (mf) counts for a large data base on the epidemiology of brugian filariasis in Shertallai, Kerala, South India are analysed. Frequency distributions of microfilarial counts partitioned by age are successfully described by zero-truncated negative binomial distributions, fitted by maximum likelihood. This analysis provides estimates of the proportion of mf-positive individuals who are identified as negative due to sampling errors, allowing the construction of corrected mf age–prevalence curves, which indicate that the observed prevalence may under-estimate the true figures by between 18 and 47%. There is no evidence from these results for a decrease in the degree of over-dispersion of parasite frequency distributions with host age, such as might be produced by the acquired immunity to infection. This departure from the pattern in bancroftian filariasis (where there is evidence of such decreases in over-dispersion; Das et al. 1990) is discussed in terms of the long history of filariasis control (and consequently low infection prevalence) in Shertallai.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1991

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References

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