Trends, Manifestations, Issues and Prospects of Chloroquine Resistance in Nigeria: A Structured Narrative Review

Abstract

Chloroquine was once central to malaria treatment in Nigeria, but widespread resistance prompted its withdrawal as first-line therapy in 2005. This narrative review characterized Nigerian research on chloroquine resistance, examined trends in use and resistance, and assessed evidence of continued use after withdrawal. PubMed and Google Scholar were searched from 1 to 14 August 2025 for English-language studies using terms related to chloroquine, Nigeria, pfcrt, K76T, pfmdr1, mutation, polymorphism, and resistance. The search covered publications from 1980 to 2025; the studies meeting the eligibility criteria were published between 1989 and 2025. Of 1,490 records retrieved, 150 full texts were assessed, and 60 studies met the eligibility criteria. Evidence was summarized by design, period, geographical distribution, and level. Observational studies predominated, while randomized trials and systematic reviews were uncommon, indicating that most evidence was surveillance-based rather than trial-based. Research was concentrated in the South West and South-South, with comparatively limited coverage in the South East and North East. Molecular evidence suggests that the prevalence of the pfcrt K76T resistance allele has declined in some settings; however, continued informal use, affordability, accessibility, and renewed exposure during the COVID-19 period may sustain drug pressure. The findings indicate uneven surveillance rather than a uniform national picture and do not establish complete restoration of chloroquine susceptibility. Nigeria should strengthen pharmacovigilance, nationwide molecular and genomic surveillance of pfcrt and pfmdr1, periodic resistance mapping, enforcement of withdrawal restrictions among Patent and Proprietary Medicine Vendors, and monitoring of informal medicine markets.