Malaria Prevalence and in vitro Antimalarial Drug Sensitivity of Plasmodium falciparum Isolates in Gombe North, Gombe State, Northeastern Nigeria

Abstract

Background: Malaria remains a significant public health challenge in Nigeria, which accounted for approximately 25.9% of estimated global malaria cases in 2023. In Gombe State, the transition to artemisinin-based combination therapies (ACTs) was necessitated by emerging resistance to older antimalarial drugs. Objectives: This study assessed the prevalence of malaria and the in vitro sensitivity profile of Plasmodium falciparum isolates to selected antimalarial drugs in Gombe North, Gombe State, Nigeria. Methodology: A cross-sectional, laboratory-based experimental design was employed, involving 1,152 participants across Gombe, Funakaye and Kwami Local Government Areas (LGAs). Malaria was diagnosed using thick blood films. In vitro drug sensitivity was assessed using a modified WHO microtest technique. Data were analysed using non-linear regression and chi-square tests. Drugs were categorised as sensitive or showing reduced sensitivity by comparing the results with IC₅₀ thresholds reported by the World Health Organization. Results: Of the 1,152 individuals examined, 719 were positive for malaria parasites, giving an overall prevalence of 62.41%. Infection was highest among children aged 6-10 and 0-5 years (65.97% and 65.79%, respectively), although differences across age groups were not statistically significant (P = 0.182). Male participants showed a significantly higher prevalence (67.34%) than females (57.95%) (P = 0.001). Spatial variation in prevalence was also significant (P = 0.005), with Kwami recording the highest prevalence (69.01%), followed by Funakaye (60.16%) and Gombe (58.07%). In vitro sensitivity assays revealed sustained susceptibility of P. falciparum isolates to artesunate, with IC₅₀ values < 10 nM in all study locations. Chloroquine and pyrimethamine demonstrated reduced sensitivity across all study areas, whereas amodiaquine remained sensitive in Funakaye and Kwami, with IC₅₀ values of 6.3 ± 0.1 nM and 29.0 ± 0.8 nM, respectively, but showed reduced sensitivity in Gombe, with an IC₅₀ value of 30.0 ± 1.2 nM. Relative potency analysis further identified artesunate as the most potent antimalarial agent, whereas chloroquine and pyrimethamine displayed markedly diminished potency. Conclusion: The findings indicate that malaria remains highly prevalent in Gombe North and that P. falciparumisolates show reduced sensitivity to older antimalarial drugs. Artesunate remained highly active in the in vitro assays, while continued surveillance of antimalarial drug sensitivity is essential to support evidence-based malaria control strategies in the region.