Abstract
BackgroundAnti-malarial drug resistance is a severe challenge for eventual control and global elimination of malaria. Resistance to sulfadoxine-pyrimethamine (SP) increases as mutations accumulate in the Pfdhfr and Pfdhps genes. This study aimed to assess the polymorphisms and prevalence of mutation in these genes in the Plasmodium falciparum infecting migrant workers returning to Wuhan, China.MethodsBlood samples were collected for 9 years (2011–2019). Parasite genomic DNA was extracted from blood spots on filter paper. The mutations were evaluated by nested PCR and sequencing. The single-nucleotide polymorphisms (SNPs) and haplotypes of the Pfdhfr and Pfdhps genes were analysed.ResultsPfdhfr codon 108 showed a 94.7% mutation rate, while for Pfdhps, the rate for codon 437 was 79.0%. In total, five unique haplotypes at the Pfdhfr locus and 11 haplotypes at the Pfdhps locus were found while the Pfdhfr-Pfdhps combined loci revealed 28 unique haplotypes. A triple mutant (IRNI) of Pfdhfr was the most prevalent haplotype (84.4%). For Pfdhps, a single mutant (SGKAA) and a double mutant (SGEAA) were detected at frequencies of 37.8 and 22.3%, respectively. Among the combined haplotypes, a quadruple mutant (IRNI-SGKAA) was the most common, with a 30.0% frequency, followed by a quintuplet mutant (IRNI-SGEAA) with a frequency of 20.4%.ConclusionThe high prevalence and saturation of Pfdhfr haplotypes and the medium prevalence of Pfdhps haplotypes demonstrated in the present data will provide support for predicting the status and progression of antifolate resistance in malaria-endemic regions and imported malaria in nonendemic areas. Additional interventions to evaluate and prevent SP resistance should be continuously considered.
Highlights
Anti-malarial drug resistance is a severe challenge for eventual control and global elimination of malaria
SP is still used for intermittent preventive treatment in infants (IPTi) and pregnant women (IPTp) during malaria-endemic regions, following the guidance of the World Health Organization (WHO) [2]
The development of drug resistance could be influenced by multiple factors, including mutation frequency, treatment costs, drug selection pressure, patient compliance, and host immunity [5, 6]
Summary
Anti-malarial drug resistance is a severe challenge for eventual control and global elimination of malaria. Malaria is caused by the Plasmodium parasite, which is transmitted to human beings via the bites of infected female Anopheles mosquitoes. It is prevalent in the tropics and subtropics, sub-Saharan Africa, as well as in Southeast Asia (SEA) and South America. In the 1980s, sulfadoxine-pyrimethamine (SP) replaced chloroquine (CQ) as the front-line anti-malaria treatment when large-scale CQ resistance developed in subSaharan African countries. The emergence, development, and continuous dissemination of Plasmodium falciparum resistance to the anti-malarial drug is considered a significant global threat for malaria control and elimination strategies [4]. Molecular markers are a useful tool for confirming that parasites are drug-resistant
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