| Summary: | <p>Abstract</p> <p>Background</p> <p><it>Plasmodium vivax </it>malaria accounts for approximately 60% of malaria cases in Kolkata, India. There has been limited information on the genotypic polymorphism of <it>P. vivax </it>in this malaria endemic area. Three highly polymorphic and single copy genes were selected for a study of genetic diversity in Kolkata strains.</p> <p>Methods</p> <p>Blood from 151 patients with <it>P. vivax </it>infection diagnosed in Kolkata between April 2003 and September 2004 was genotyped at three polymorphic loci: the <it>P. vivax </it>circumsporozoite protein (<it>pvcs</it>), the merozoite surface protein 1 (<it>pvmsp</it>1) and the merozoite surface protein 3-alpha (<it>pvmsp</it>3-alpha).</p> <p>Results</p> <p>Analysis of these three genetic markers revealed that <it>P. vivax </it>populations in Kolkata are highly diverse. A large number of distinguishable alleles were found from three genetic markers: 11 for <it>pvcs</it>, 35 for <it>pvmsp</it>1 and 37 for <it>pvmsp</it>3-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%.</p> <p>Conclusion</p> <p>These results indicate that the <it>P. vivax </it>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.</p>
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