Dynamic Interaction between Recorded Cases of Typhoid and Malaria in Specialist Hospital Sokoto State, Nigeria: A Vector Autoregression VAR approach

Abstract

This study examines the dynamic relationship between monthly malaria and typhoid cases in Specialist Hospital Sokoto State, Nigeria using a VAR (1) model. Data on reported cases were analyzed to assess persistence, cross-lagged effects, and residual correlation. Results show malaria exhibits strong persistence β = 0.943, p < 0.001, with 94% of cases carrying over monthly. Significant bidirectional cross-effects exist: lagged typhoid increased current malaria by 1.151 units, p = 0.028, while lagged malaria increased current typhoid by 0.316 units, p < 0.001. Typhoid demonstrated no significant self-persistence β = 0.433, p = 0.414. Residual correlation was weak at 0.19, indicating interaction occurs through lagged effects rather than contemporaneous shocks. The findings support diagnostic overlap and delayed reporting rather than direct biological co-infection. The results confirm that malaria transmission is highly persistent, while malaria-typhoid interaction is mediated by health-system factors. Recommendations emphasize sustained malaria vector control, improved laboratory confirmation, stronger WASH interventions, and integrated surveillance.