Increasing artemisinin partial resistance (ArtR) due to mutations in the gene encoding Kelch13 (Pfk13) protein in eastern Africa is of urgent concern, and mutations, such as Pfk13 P441L, continue to emerge. We used an amplicon deep-sequencing panel to estimate the prevalence of ArtR Pfk13 mutations in samples collected between 2018 and 2023 in southern Zambia. Pfk13 P441L was present in 30 of 501 samples (6%), and prevalence increased over time (0% to 7.2%). Further studies of the P441L mutation are needed to document its geographical origin, distribution and impact on treatment outcomes.

The authors have declared no competing interest.

This work was supported by funds from the National Institute of Allergy and Infectious Diseases (NIAID) of the National Institutes of Health [grant numbers U19AI089680 to WJM, K24AI134990 to JJJ and T32AI138953-03 to AM], the Bloomberg Philanthropies, and the Johns Hopkins Malaria Research Institute.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The samples and data used in this study were a part of two IRB-approved studies. The Against Transmission Of Malaria With Everyone (ANTOOMWE) study had ethical approval from the Johns Hopkins Bloomberg School of Public Health (Baltimore, Maryland) under IRB no: 00003467 and the Tropical Diseases Research Center (TDRC under IRB no: TDRC/ERC/2010/14/11. The Magnifying the Utility of Surveillance in Elimination-focused Malaria Operations (MUSEMO) study has ethical approval from the Johns Hopkins Bloomberg School of Public Health (Baltimore, Maryland) under IRB no: 00019447 and Macha Research Trust (Macha, Zambia) under IRB no: 0007649. Written informed consent was obtained from adults 18 years and older, and parental permission from parents or guardians of individuals younger than 18 years. Oral assent was obtained from children between 12 and 18 years.

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Sequencing data are available at (SRA number pending). Under the National Health Research Act, the Government of Zambia does not allow public access to metadata collected in Zambia. All investigators interested in the datasets supporting the conclusions of this article are required to submit a written request to the Ministry of Health. Contact the Macha Research Trust IRB Chairperson (mrt.irb@macharesearch.org, +260979402560) to coordinate the request.