Molecular Characterisation of Plasmodium falciparum in Children with Uncomplicated Malaria in Homa-Bay, Kenya; Two Decades Post-Adoption of Artemisinin-Based Combination Therapies

BACKGROUND The emergence and spread of P. falciparum parasites with decreased susceptibility to Artemisinin-based combination therapies (ACTs) is causing global concern. Active surveillance of the emergence of resistance in malaria-endemic areas is important for efficient management of the infection. Slow parasite clearance following treatment with artemisinin derivatives is associated with single-nucleotide polymorphism in the propeller domain of the Plasmodium falciparum kelch13 ( pfk13 ) gene. This study investigated the polymorphism in the Pfk 13 gene and parasite population diversity of Plasmodium falciparum in children with uncomplicated malaria in Homa-Bay County, Kenya, two decades post-adoption of Artemisinin-based combination treatment. METHODS This study assessed polymorphisms on the pfk13 gene and parasite population diversity in 86 PCR-confirmed Plasmodium falciparum positive samples obtained from children between six months and fifteen years old. The parasite diversity was determined by nested PCR amplification of msp1 and msp2 genes and direct PCR amplification of the polyα microsatellite locus followed by capillary electrophoresis. Sanger sequencing was carried out on samples with successful amplification of the Pfk13 gene to determine polymorphisms. The sequenced data were analyzed by Geneious Prime software (version 2024.0.7). RESULTS The study did not report validated or candidate mutations as classified by WHO. However, the previously described mutations P667S and P667L were detected on Pfk13 gene. Additionally, this study reported polyclonal infection in 86% of the samples and a parasite diversity of 0.91. CONCLUSION In conclusion, this study demonstrated the circulation of P. falciparum parasites with mutant alleles on the kelch13 gene in Homa-Bay County, Kenya. The study also showed a high frequency of polyclonal infections and high parasite genetic diversity, suggesting a high transmission rate. The high polyclonal infection and diversity show that malaria transmission is still high in this region; hence, the control measures need to be heightened. The observed polymorphisms on Pfk13 need close monitoring, especially since the P667S mutation has been reported to cause artemisinin resistance in Rwanda, and the effect of mutation P667L is yet to be known.