Mathematical Analysis of a Seasonal Malaria Chemoprevention (SMC) Intervention in Children Under 5 Years: Application to Senegal

Malaria remains a major cause of morbidity and mortality among children under 5 years old in Senegal. To alleviate this burden, Seasonal Malaria Chemoprevention (SMC) administers antimalarial drugs during the high transmission season. Currently, in Senegal, SMC targets children aged 3 months to under 10 years. This study, based on a mathematical SIR-SI model, evaluates the effectiveness of this intervention, focusing specifically on children under 5 years old. We developed a coupled SIR-SI model that integrates the transmission dynamics between humans and mosquitoes, incorporating the SMC treatment rate (η) into the differential equations to model the chemoprevention effect. The Jacobian matrix was calculated for both disease-free and endemic equilibria, and eigenvalues were analyzed to assess their stability. Our results show that the basic reproduction number R₀, calculated using the next-generation matrix method, depends on key parameters such as transmission rates, recovery rates, mosquito mortality rates, and particularly the SMC treatment rate (η). Increasing this rate significantly reduces R₀, thereby stabilizing the disease-free equilibrium. Numerical simulations, based on biologically realistic parameters, confirm that SMC effectively reduces R₀ and limits malaria transmission. While our findings suggest that targeting children under 5 years old could be sufficient to significantly reduce transmission, a comparative analysis including the 0-5 and 0-10 age groups would be necessary to further validate this assertion, considering local dynamics and recent shifts in malaria burden toward older age groups. This study highlights the critical role of SMC in malaria control and provides a scientific basis for refining and optimizing intervention strategies in Senegal.