Abstract / Summary
Malaria has been one of the most morbid and fatal illnesses among the under-five children in Nigeria, with most of the burden being disproportionate in the endemic regions like Rivers State. Malaria transmission is a complex process shaped by interactions between the mosquito vector, the Plasmodium parasite, the human host and the environment, and mathematical models are well suited to capturing these interacting drivers. Despite the scaling up of key interventions in the State, transmission persists among this vulnerable group, which underscores the need for data-driven solutions to inform targeted control measures. A deterministic SEIR-SEI compartmental model was formulated to describe malaria transmission among children under-five years old. Biological parameters were obtained from the literature, and transmission intensity was calibrated to the parasite prevalence for the study area reported in the 2021 Nigeria Malaria Indicator Survey; the effective reproduction number was then derived using the next-generation-matrix method. Effective reproduction number (Re) was estimated and intervention scenarios of insecticide-treated nets (ITNs) and artemisinin-based combination therapy (ACT) were modelled. Data were cleaned and analysed using R programming software. The effective reproduction number under current intervention coverage was estimated to be well above one (of the order of 2.6), indicating persistent transmission; in the absence of interventions it would be substantially higher (approximately 8.5). Sensitivity analysis identified the mosquito biting rate (+ 1.0) and the transmission probabilities and vector-to-host ratio (each about + 0.5) as the strongest positive influences on transmission, and insecticide-treated-net coverage (-1.08), ITN-induced mosquito mortality (-0.42) and natural mosquito mortality (-0.35) as the strongest negative influences. Scenario analysis showed that current interventions roughly halve the endemic infection prevalence (from about 15.8% without control to 7.5%), while combined scale-up of net use (at least 80%) and ACT drives the reproduction number below one (to about 0.8), projecting interruption of transmission. Neither intervention alone at currently attainable coverage was sufficient to interrupt transmission: current control roughly halves the endemic prevalence of infection but leaves the effective reproduction number at about 2.6. Only the combined scale-up of insecticide-treated-net use to at least 80% together with expanded effective ACT lowered the reproduction number below one (to about 0.8), a gain beyond what current programmes achieve. This underscores the need for integrated, data-driven approaches to malaria control in Rivers State.