Genetic polymorphisms associated with sulphadoxine-pyrimethamine drug resistance among Plasmodium falciparum field isolates in malaria endemic areas of Assam.

BACKGROUND

The emergence of antimalarial drug resistance malaria parasite is widespread in North eastern region of India. During January 2012-December 2013, we conducted active surveillance for detection of antifolate resistance-associated genetic polymorphisms in Plasmodium falciparum malaria parasite from different malaria endemic areas of Assam.

MATERIALS AND METHODS

A total of 281 field samples were collected from suspected malaria patients of which 106 malaria P. falciparum positive cases were detected in microscopic slide examination. A nested PCR was done for amplification of a 648 bp portion of the dhfr gene and 710 bp portion of the dhps gene.

RESULTS

Mutation analysis revealed existence of three different haplotypes of the P. falciparum dhfr gene of which ANRNI was highly prevalent (90%). Triple mutant haplotypes AIRNI (N51I+C59R+S108N) of the dhfr gene associated with pyrimethamine resistance were prevalent in Chirang district of Assam. Whereas, dhps mutation study revealed that triple mutant haplotype AGEAA (S436A+A437G+K540E) associated with Sulphadoxine resistance was found among 26% of P. falciparum field isolates. However, P. falciparum dhfr-dhps two locus mutation analysis showed that there were a total of nine dhfr-dhps genotypes.

CONCLUSION

It was noticed that 93.62% (88/94) isolates had mutations in the sequences of both enzymes, which is an indication of prevalence of high grade of Sulphadoxine - pyrimethamine resistance in P. falciparum malaria parasites in Assam.