Objective: Understanding the epidemiological features of malaria is a key step to monitoring and quantifying the impact of the current control efforts to inform future ones. This study establishes the prevalence and frequency of malaria in a forest–savannah ecozone for 5 consecutive years in Cameroon. Methods: A retrospective study was conducted in 3 health centers of Makenene from 2016 to 2020, a period covering the second long-lasting insecticide net mass distribution campaign. Malaria infectious records were reviewed from laboratory registers. The difference in exposure to malaria was estimated using a regression logistic model. Results: A total of 13525 patients underwent malaria diagnostic tests, with a general malaria prevalence of 65.3%. A greater prevalence of malaria was observed in males (68.39%) compared to females (63.14%). The frequency of consultations in health centers was dominated by females, with a gender ratio (M/F) of 0.66. Annual trends in malaria prevalence slightly varied from 2016 to 2020, exceeding 60%: 65.2% in 2016; 66.7% in 2017, 68.1% in 2018, 63.2% in 2019, and 65.3% in 2020, with a significant seasonal variation (p < 0.0001). The highest malaria prevalence was observed during the short rainy season, no matter the year. Among positive cases, the most represented age groups were 6–15 (p < 0.0001), followed by those under 5, while the age group >25 years was the least represented. Conclusion: Close monitoring and additional intervention measures for malaria control are needed, as are more studies on vector bionomics and transmission patterns.

Antimalarial drug resistance remains a significant challenge in the fight against malaria in Cameroon. Given the high prevalence of malaria in Makenene in central Cameroon and the limited knowledge of drug resistance profiles in the area, the prevalence of Plasmodium falciparum drug resistance genetic markers was assessed. 185 samples from asymptomatic individuals with P. falciparum parasitaemia collected between September and October 2021 were sequenced for the Pfdhfr, Pfdhps, Pfcrt, Pfmdr1, and PfK13 genes. One hundred percent of the samples harboured parasites with triple mutant PfdhfrI₅₁R₅₉N₁₀₈I₁₆₄ (IRNI), associated with high level of resistance to pyrimethamine. The septuple mutant PfdhfrIRNI and PfdhpsA₄₃₆G₄₃₇K₅₄₀G₅₈₁S₆₁₃ (AGKGS), associated with resistance to sulfadoxine-pyrimethamine, was detected in 62.0 % of the isolates. The new Pfdhps I431V mutation was observed in 18.8 %. The octuple mutant IRNI + VAGKGS haplotype, overrepresented in pregnant women taking intermittent preventive treatment with sulfadoxine-pyrimethamine, was found in 17.4 %. The Pfdhps K540E mutation, linked to "super" resistance to sulfadoxine, was only detected in 1.9 %. The Pfcrt C₇₂V₇₃I₇₄E₇₅T₇₆ haplotype, implicated in chloroquine resistance, was absent in Makenene. The Pfmdr1 N₈₆F₁₈₄ haplotype, selected in parasites with a recrudescence in patients treated with artemether-lumefantrine, was found in 73.2 %. No isolate harboured the Y₈₆Y₁₈₄ haplotype, selected in parasites with recrudescence in patient treated with dihydroartemisinin-piperaquine. Moreover, no mutation associated with artemisinin partial resistance was detected in PfK13. The in-depth analysis of genetic mutations associated with antimalarials resistance in this study, notably those with a high prevalence of mutations on the Pfdhfr and Pfdhps genes, highlights the immediate need for proactive strategies to combat resistance in Makenene. Continuous monitoring, including molecular and in vivo surveillance is crucial to uphold the effectiveness of current treatments and, more particularly, artemisinin-based combination therapies, and to enable better decision-making on effective treatment policy in Cameroon and in Africa as a whole.