Day 3 parasitemia andPlasmodium falciparum Kelch 13mutations among uncomplicated malaria patients treated with artemether-lumefantrine in Adjumani district, Uganda

Artemisinin resistance threatens malaria control and elimination efforts globally. Recent studies have reported the emergence ofPlasmodium falciparumparasites tolerant to artemisinin agents in sub-Saharan Africa, including Uganda. The current study assessed the day 3 parasite clearance and its correlation withP. falciparum K13propeller gene (pfkelch13) mutations inP. falciparumparasites isolated from patients with uncomplicated malaria under artemether-lumefantrine (AL) treatment. This study enrolled 100P. falciparum-positive patients to whom AL was prescribed between 09/September/2022 and 06/November/2022. Blood samples were collected in EDTA tubes before treatment initiation (day 0) and on day 3. Parasitemia was assessed by microscopy from blood smears and quantitative polymerase chain reaction (qPCR) from the DNA extracted. The day 0 parasiteK13gene was sequenced using Sanger sequencing. Sequence data were analysed using MEGAversion11 software. The data were analysed using STATAversion15, and the Mann‒Whitney U test was used to compare PCR parasite clearance on day 3 using the comparative CT value method andpfkelch13mutations.

The prevalence of day 3 parasitaemia was 24% (24/100) by microscopy and 63% (63/100) by qPCR from the AL-treated patients.P. falciparum K13-propeller gene polymorphism was detected in 18.8% (15/80) of the day 0 DNA samples. TheK13mutations found were C469Y, 12.5% (10/80); A675V, 2.5% (2/80); A569S, 1.25%, (1/80), A578S, 1.25%, (1/80) and; F491S, 1.25%, (1/80) a new allele not reported anywhere. The C469Y mutation, compared to the wild-type, was associated with delayed parasite clearancep=0.0278, Hodges-Lehmann estimation 3.2108 on the log scale, (95%CI 1.7076, 4.4730).

There was a high prevalence of day 3P. falciparumamong malaria patients treated using artemether-lumefantrine. We conclude that theK13mutation associated with artemisinin resistance byP. falciparumis present in Adjumani district, Uganda. This necessitates regular surveillance of the effectiveness and efficacy of artemether-lumefantrine in the country.