Mathematical Modelling of East Coast Fever and Foot-and-Mouth Disease Co-Infection in Cattle in Malawi

Abstract

This study develops a mathematical model to describe the co-infection dynamics of East Coast Fever (ECF) and Foot-and-Mouth Disease (FMD) in cattle, with a focus on livestock production systems in Malawi. The model accounts for direct transmission of FMD among cattle and tick-mediated transmission of ECF, allowing for progression from single infection to co-infection. Threshold quantities in the form of basic reproduction numbers are derived to analyze the stability of disease-free and endemic equilibria. Sensitivity analysis indicates that ECF transmission is strongly influenced by tick mortality and vector-to-cattle transmission, while FMD dynamics are primarily driven by cattle recruitment and direct contact rates. An optimal control framework incorporating vaccination, treatment, and vector control is formulated to assess the effectiveness of intervention strategies. Numerical simulations, using parameter values relevant to Malawian cattle farming, show that the disease-free equilibrium is unstable under baseline conditions, reflecting the endemicity of ECF and the recurring nature of FMD outbreaks. However, combined intervention strategies substantially reduce infection prevalence and can eliminate both diseases. These findings highlight the importance of integrated control measures targeting both cattle and tick populations and provide a quantitative framework to support improved management of ECF-FMD co-infection in Malawi.