Research

Heterogeneous distribution of Plasmodium falciparum drug resistance haplotypes in subsets of the host population

Sonja Schoepflin¹ , Jutta Marfurt¹ , Mary Goroti² , Moses Baisor² , Ivo Mueller² and Ingrid Felger¹

¹  Swiss Tropical Institute, Department of Medical Parasitology and Infection Biology, Socinstr.57, 4002 Basel, Switzerland

²  Papua New Guinea Institute of Medical Research, Madang, P.O. Box 378, M.P. 511, Papua New Guinea

author email corresponding author email

Malaria Journal 2008, 7:78doi:10.1186/1475-2875-7-78

Published:	6 May 2008

Abstract

Background

The emergence of drug resistance is a major problem in malaria control. For mathematical modelling of the transmission and spread of drug resistance the determinant parameters need to be identified and measured. The underlying hypothesis is that mutations associated with drug resistance incur fitness costs to the parasite in absence of drug pressure. The distribution of drug resistance haplotypes in different subsets of the host population was investigated. In particular newly acquired haplotypes after radical cure were characterized and compared to haplotypes from persistent infections.

Methods

Mutations associated with antimalarial drug resistance were analysed in parasites from children, adults, and new infections occurring after treatment. Twenty-five known single nucleotide polymorphisms from four Plasmodium falciparum genes associated with drug resistance were genotyped by DNA chip technology.

Results

Haplotypes were found to differ between subsets of the host population. A seven-fold mutated haplotype was significantly reduced in adults compared to children and new infections, whereas parasites harbouring fewer mutations were more frequent in adults.

Conclusion

The reduced frequency of highly mutated parasites in chronic infections in adults is likely a result of fitness costs of drug resistance that increases with number of mutations and is responsible for reduced survival of mutant parasites.