Evaluation of Dihydrofolate Reductase (Dhfr) Gene, Related to Plasmodium Falciparum Pyrimethamine Resistance in Imported Malaria Cases in Iran

Antimalarial drug resistance is one of the key challenges that the governments face in the fight against malaria. Molecular surveillance of antimalarial drug resistance supports early detection of how the recommended treatments work. This allows immediate action to reduce any threat and prevent it from spreading. Therefore, the aim of this study was to evaluate the frequency of dihydrofolate reductase (dhfr) mutants in Plasmodium falciparum resistance to primethamine in Iranian malaria patients.

In 2020, 27 patients (21 males and 5 females) with imported P. falciparum cases were studied. The Nested-PCR technique first confirmed the species identity for all samples and then amplified by the Semi-Nested-PCR method in order to detection of single nucleotide polymorphisms (SNPs) in dhfr gene related to pyrimethamine resistance.

All samples in the 18S rRNA gene had species-specific bands for P. falciparum strains. In the sequence analysis of pfdhfr gene amplification after comparison with the standard strain (wild type), 21 patients had a double mutation (C59R+S108N) and 6 patients had a triple mutation (N51I+ C59R+S108N) of pyrimethamine resistance.

The results of this study showed that the susceptibility of P. falciparum to pyrimethamine in the treatment of malaria is significantly reducing. These findings have raised concerns about pyrimethamine resistance in P. falciparum. Due to the high emergence of double and triple mutants related to pyrimethamine resistance, the malaria surveillance and treatment systems in the region should pay more attention to the use of pyrimethamine.