Dynamic insights into malaria-onchocerciasis co-disease transmission: mathematical modeling, basic reproduction number and sensitivity analysis

Onchocerciasis and malaria stand as prominent vector-borne diseases, posing significant global health challenges in tropical regions. This study concerns the dynamics of co-disease transmission of onchocerciasis and malaria within the human and vector (female Anopheles mosquitoes and blackflies) host community. A deterministic onchocerciasis-malaria co-disease model is formulated to qualitatively analyze its existence, uniqueness, boundedness, positivity and asymptotic stability. In addition, we evaluated the effective basic reproduction number R-mr using the next generation matrix method, and through the utilization of parameters and variables drawn from existing literature, our simulations revealed that the the basic reproduction number of malaria R-1 surpasses that of onchocerciasis R-2, resulting in the persistence and prevalence of both diseases. Sensitivity analysis of the model parameters concerning R-mr indicate that recruitment rates of humans and vectors, co-disease transmission rates, biting rates of vectors, modification parameters reflecting increased infectiousness, loss of vision, and mortality induced by malaria are pivotal factors influencing R-mr. These factors drive the prevalence of the co-disease unless effective intervention strategies are implemented. In conclusion, we conducted simulations to probe the behavior of co-disease model variables, the impact of co-disease transmission rates on R-mr, and the effects of transmission and recovery rates on different population classes within the model. These findings emphasizes the significance of targeted interventions to curb the persistence and prevalence of both diseases.