Molecular epidemiology of drug-resistant malaria in western Kenya highlands

Daibin Zhong,Liwang Cui,Andrew Githeko,Yaw Afrane,David M Menge,Guiyun Yan

doi:10.1186/1471-2334-8-105

Abstract

BackgroundSince the late 1980s a series of malaria epidemics has occurred in western Kenya highlands. Among the possible factors that may contribute to the highland malaria epidemics, parasite resistance to antimalarials has not been well investigated.MethodsUsing parasites from highland and lowland areas of western Kenya, we examined key mutations associated with Plasmodium falciparum resistance to sulfadoxine – pyrimethamine and chloroquine, including dihydrofolate reductase (pfdhfr) and dihydropteroate synthetase (pfdhps), chloroquine resistance transporter gene (pfcrt), and multi-drug resistance gene 1 (pfmdr1).ResultsWe found that >70% of samples harbored 76T pfcrt mutations and over 80% of samples harbored quintuple mutations (51I/59R/108N pfdhfr and 437G/540E pfdhps) in both highland and lowland samples. Further, we did not detect significant difference in the frequencies of these mutations between symptomatic and asymptomatic malaria volunteers, and between highland and lowland samples.ConclusionThese findings suggest that drug resistance of malaria parasites in the highlands could be contributed by the mutations and their high frequencies as found in the lowland. The results are discussed in terms of the role of drug resistance as a driving force for malaria outbreaks in the highlands.

Highlights

Since the late 1980s a series of malaria epidemics has occurred in western Kenya highlands
Among the many factors that may contribute to the highland malaria epidemics, resistance of the parasites to multiple antimalarials has not been extensively investigated
Over 90% of samples were successfully amplified at the 17 test codons, and polymorphisms were detected at 10 of 17 codons screened (Table 1)

Summary

Introduction

Since the late 1980s a series of malaria epidemics has occurred in western Kenya highlands. Among the possible factors that may contribute to the highland malaria epidemics, parasite resistance to antimalarials has not been well investigated. Malaria is a major public health problem in sub-Saharan. >1,500 m above sea level) were either free of malaria or had very low incidences of the disease; since the late 1980s a series of malaria epidemics has occurred [3-. Among the many factors that may contribute to the highland malaria epidemics, resistance of the parasites to multiple antimalarials has not been extensively investigated. Resistance to antimalarial drugs is one of the major obstacles for effective malaria control. The first case of chloroquine (CQ) resistance in Kenya was reported in [10]. In 1993, resistance levels had reached 70%

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Results

Discussion

Conclusion