A scoping review of antimalarial drug resistance markers in Kenya (1987–2022): toward a National Surveillance Framework and Data Repository

The identification of genetic markers has revolutionized the assessment of antimalarial drug resistance. Tracking the molecular markers of resistance emerged as a valuable tool over 60 years ago, following the identification of sulfadoxine-pyrimethamine (SP) genetic resistance markers, dhfr and dhps. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines were used. PubMed/MEDLINE, Embase, Scopus, Google Scholar and Web of Science were systematically searched to identify studies on antimalarial drug resistance markers in Kenya published in English between 01-Jan-1995 and 31-Oct-2024. The national analysis showed a regional shift in the timelines from the mutant to wild-type crt genotype and similarly from the mutant (CVIET) to wild-type (CVMNK) microhaplotype, with the Coast occurring earlier in 2002, while Western Kenya the change occurred later in 2008. MDR1 codons 86 and 1246, also genetic markers of chloroquine resistance have shown a full reversion to the wildtype, that was rising since 1994 in the Coast and 2003 in Western Kenya. By the time drug policy changed to SP in 1999 the dhps mutant genotype was already rising from 1996 in the Coast and 1998 from Western Kenya, while the dhfr codon 108 shift to mutant occurred as early as 1988 in the Coastal parasite populations. The World Health Organization-validated k13 mutations were first described, P553L, in 2006 in Kisumu. This aggregation of data across Kenya demonstrates the utility of this scoping review. The compilation and standardization of over 100 studies provides a high-level, structured overview of when and where resistance markers have been surveyed. This establishes a foundational national repository to support strategic surveillance planning by the Kenya NMCP.