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Open Access Research

Genetic diversity of Plasmodium vivax in Kolkata, India

Jung-Ryong Kim1, Mallika Imwong1*, Amitabha Nandy2, Kesinee Chotivanich1, Apichart Nontprasert1, Naowarat Tonomsing1, Ardhendu Maji2, Manjulika Addy2, Nick PJ Day3, Nicholas J White13 and Sasithon Pukrittayakamee14

Author Affiliations

1 Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand

2 Department of Parasitology and Protozoology, the Calcutta School of Tropical Medicine, Kolkata, India

3 Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, Old Road, Headington, Oxfordshire OX3 7LJ, UK

4 The Royal Institute of Thailand, Grand Palace, Bangkok, Thailand

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Malaria Journal 2006, 5:71  doi:10.1186/1475-2875-5-71

Published: 14 August 2006

Abstract

Background

Plasmodium vivax malaria accounts for approximately 60% of malaria cases in Kolkata, India. There has been limited information on the genotypic polymorphism of P. vivax in this malaria endemic area. Three highly polymorphic and single copy genes were selected for a study of genetic diversity in Kolkata strains.

Methods

Blood from 151 patients with P. vivax infection diagnosed in Kolkata between April 2003 and September 2004 was genotyped at three polymorphic loci: the P. vivax circumsporozoite protein (pvcs), the merozoite surface protein 1 (pvmsp1) and the merozoite surface protein 3-alpha (pvmsp3-alpha).

Results

Analysis of these three genetic markers revealed that P. vivax populations in Kolkata are highly diverse. A large number of distinguishable alleles were found from three genetic markers: 11 for pvcs, 35 for pvmsp1 and 37 for pvmsp3-alpha. These were, in general, randomly distributed amongst the isolates. Among the 151 isolates, 142 unique genotypes were detected the commonest genotype at a frequency of less than 2% (3/151). The overall rate of mixed genotype infections was 10.6%.

Conclusion

These results indicate that the P. vivax parasite population is highly diverse in Kolkata, despite the low level of transmission. The genotyping protocols used in this study may be useful for differentiating re-infection from relapse and recrudescence in studies assessing of malarial drug efficacy in vivax malaria.