Molecular variation of Plasmodium vivax dehydrofolate reductase in Mexico and Nicaragua contrasts with that occurring in South America.

OBJECTIVE

To research mutations associated to pyrimethamine resistance in dihydrofolate reductase (pvdhfr) of Plasmodium vivax from Mexico and Nicaragua and compare it to that reported in the rest of America.

MATERIALS AND

METHODS

Genomic DNA was obtained from P. vivax-infected blood samples. A pvdhfr gene fragment was amplified and sequenced. The identified gene variations were compared to those observed in other affected sites of America.

RESULTS

No mutations in pvdhfr were detected in P. vivax from Mexico and Nicaragua. One synonymous change and variation in the repeat domain was detected in Nicaraguan parasites. In South America, a high frequency of variant residues 58R and 117N associated to pyrimethamine resistance was reported.

CONCLUSIONS

The lack of polymorphisms associated with pyrimethamine resistance suggests that drug-resistant P. vivax has not penetrated Mesoamerica, nor have local parasites been under selective pressure. These data contribute to establish the basis for the epidemiological surveillance of drug resistance.