Assessment of Malaria Parasite Recrudescence After Artemisinin-Based Combination Therapy in Febrile Patients in Rivers State, South South Nigeria

Plasmodium falciparum recrudescence following artemisinin-based combination therapy represents an early warning signal for emerging treatment failure that demands systematic therapeutic efficacy monitoring in malaria-endemic Nigerian states. This study assesses malaria parasite recrudescence after artemisinin-based combination therapy in febrile patients in Rivers State, South South Nigeria. A prospective therapeutic efficacy cohort design conforming to WHO standard protocols was employed, enrolling 250 uncomplicated malaria patients aged 6 months to 59 months from three government health facilities in Port Harcourt, Bonny, and Eleme Local Government Areas. Patients received artemether-lumefantrine as standard first-line therapy under direct observation. Peripheral blood thick films were examined on days 1, 2, 3, 7, 14, 21, and 28 post-treatment. Molecular genotyping using msp1 and msp2 markers distinguished recrudescence from reinfection. Parasite clearance times and adequate clinical and parasitological response rates were calculated. Evidence from 2020 to 2024 indicates that artemether-lumefantrine maintains above 95 percent efficacy in most Nigerian states, but localised recrudescence signals in South-South Nigeria warrant closer investigation. This study provides Rivers State-specific efficacy data for the national therapeutic efficacy monitoring network. Findings will be submitted to the National Malaria Elimination Programme and the WHO Global Malaria Programme for regional policy review. Keywords: malaria recrudescence, artemisinin-based combination therapy, therapeutic efficacy, Rivers State, Plasmodium falciparum.