The rising use of sulfadoxine/pyrimethamine (SP) in the treatment of chloroquine (CQ)-resistant Plasmodium falciparum has resulted in increased exposure to P. vivax isolates in Iran, where both species are being circulated. In this investigation, the frequency of pvdhfr and pvmdr-1 mutants was assessed in P. vivax strains during 2001-2016 after the introduction of SP/CQ in malarious areas of Iran. The P. vivax isolates (n, 52) were obtained from autochthonous samples in Southeast Iran during 2015-2016. The genomic DNA was extracted and examined using nested polymerase chain reaction-(PCR) and sequencing. Mutations were detected in pvdhfr codons P33L (21.2%), T61 M (25%), S93H (3.9%), and S117 T (1.9%) and 5 isolates showed double mutations (33 L/61 M, 7.7%; 33 L/117 T, 1.9%). No mutation was identified in pvdhfr codons F57 and S58. The pvmdr-1 1076 L mutation was detected in 93.3% of P. vivax isolates. The findings indicated that the frequency of three codons of pvdhfr F57/S58/S117 has decreased from 2001 (1.05%/7.0%/16.9%) to 2016 (0%/0%/1.9%). Genomic analysis of pvmdr-1 showed that the frequency of 1076 L has gradually increased from 2013 (93%) to 2016 (93.3%) (P > .05). The results demonstrated that P. vivax isolates are probably being exited under SP pressure, which reflects the appropriate level of training for field microscopists, as established by Iranian policymakers. Emergent pvdhfr codons 33L, 61M, and 93H should be noticed in plausible drug tolerance and treatment plans. The high prevalence of pvmdr-1 1076L mutation shows that efficacy of CQ combination with primaquine may be in danger of being compromised, however further investigations are needed to evaluate the clinical importance of CQ-resistant P. vivax isolates.
Keywords: Drug resistance markers; Iran; Plasmodium vivax; Polymorphism.
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