MATHEMATICAL ANALYSIS OF MALARIA-TYPHOID CO-INFECTION DYNAMICS WITH ENVIRONMENTAL DRIVERS

Malaria and typhoid fever pose significant health challenges in endemic regions, particularly in sub-Saharan Africa, due to environmental factors such as poor sanitation, stagnant water, and fluctuating temperatures. This study presents a deterministic compartmental model for co-infection dynamics of malaria and typhoid fever, incorporating both direct (human-to-human) and indirect (environment-to-human) transmission. Sub-models for malaria, typhoid and co-infection are analyzed to establish positivity, boundedness, and disease-free equilibrium (DFE). The basic reproduction numbers are derived using the next-generation matrix method. Stability of the DFE is shown when is less than , particularly under the condition, and and unstable when . Numerical simulations assess the impact of environmental decay pathogen shedding and breeding vector growth on disease persistence. Sensitivity analysis reveals key drivers influencing disease persistence. The results underscore the importance of integrated interventions targeting both environmental and host-based transmission pathways to reduce the burden of malaria-typhoid co-infection.