Unraveling Key Chloroquine Resistance-Associated Alleles Among Plasmodium falciparum Isolates in South Darfur State, Sudan Twelve Years After Drug Withdrawal

Abstract

Background: Due to the increasing resistance of Plasmodium falciparum to chloroquine (CQ) in Sudan, a shift from CQ to artesunate combined with sulfadoxine/pyrimethamine as a first-line treatment for uncomplicated falciparum malaria was adopted in 2004. This study aimed to determine the frequency distribution of K76T and N86Y mutations in P. falciparum chloroquine resistance transporter (pfcrt) and P. falciparum multidrug resistance 1 (pfmdr1) genes as key markers of resistance to CQ among P. falciparum isolates from patients in Nyala district of South Darfur state, west of Sudan. Methods: A descriptive, cross-sectional study was conducted among 75 P. falciparum isolates from Sudanese patients diagnosed with falciparum malaria mono-infection. Parasite DNA was extracted from dried blood spots and amplified using nested PCR. Restriction fragment length polymorphism (RFLP) was used to detect genetic polymorphisms in codons 76 of pfcrt and 86 of pfmdr1. Results: The wild-type pfcrt K76 allele was observed among 34.7% of isolates, the mutant 76T allele among 20.0%, and the mixed-type K76T allele among 45.3%. For pfmdr1, 54.7% of isolates harbored the wild-type N86 allele, 5.3% had the mutant 86Y allele, and 40.0% had the mixed-type N86Y allele. Conclusion: The key molecular markers associated with CQ resistance are still circulating in high frequency among P. falciparum isolates in South Darfur state about twelve years after the official withdrawal of the drug for uncomplicated falciparum malaria.