Impact of age-structured migration on malaria burden: A modelling-empirical analysis in sub-Saharan Africa

Malaria transmission in Sub-Saharan Africa is strongly influenced by seasonal climatic variations and human mobility, particularly occupation-driven rural-to-urban migration. These dynamics contribute to persistent endemicity and periodic outbreaks, especially during the monsoon season. To capture the interplay between age-specific migration and malaria transmission, a generalized compartmental model is formulated that incorporates both human and vector populations, with age-specific demographic and epidemiological characteristics. The model includes three distinct age groups to reflect heterogeneity in susceptibility, exposure, and mobility patterns. The basic reproduction number R ₀ is derived using the next-generation matrix approach to characterize disease invasion thresholds. Local and global stability of the equilibria are analyzed via Lyapunov methods, with application of a graph-theoretic approach. The model was validated using multiyear malaria reported case data from Ouagadougou, combined with annual migration records from Kossi province, Burkina Faso. The incidence pattern in different age-cohorts was nicely explained by the model with age-specific migration. Qualitative analysis and long-term simulation dynamics indicate the emergence of nonlinear amplification and synchrony in infection prevalence is partially driven by migration in different age-cohorts. This analysis, integrating empirical data provide robust insights for understanding malaria dynamics in the context of behavioural and demographic mobility, and supports the design of targeted intervention strategies in regions with pronounced seasonal migration.