molecular characterization of dihydrofolate reductase-thymidylate synthase gene concerning antifulate resistance of plasmodium vivax

background: the recently reported resistance to antimalarials contributes to making the control of ma­laria more difficult. there is a need to evaluate the current antimalaria regimens to prevent this emerging problem. the aim of this study was to determine dihydrofolate reductase-thymidylate synthase gene mu­tation ( pvdhfr ) regarding antifulate resistance in plasmodium vivax . methods : from 2007 to 2009, 117 p. vivax infected blood samples collected from two regions of hor­mozgan province, south of iran were analyzed using pcr, semi-nested-pcr and rflp methods. results: eighty four isolates (71.8 %) showed no mutation in pvdhfr gene of p. vivax known as wild type and 33 (28.2%) of the samples revealed nine single (7.7%), twenty two double (18.8%) and two (1.7%) triple mutations. conclusion: genetic diversity was observed by molecular methods in pvdhfr gene of p. vivax in hor­mozgan province suggests that the antifolate falciparum malaria drug (fansidar) is proportionally affecting p . vivax dhfr mutation. therefore, more studies to evaluate antimalarial drugs that should preferably be effective against both p. vivax and p. falciparum are recommended.