We answer the stability question of the large scale SIS model describing transmission of highland malaria in Western Kenya in a patchy environment, formulated in . There are two equilibrium states and their stability depends on the basic reproduction number, Ro . If Ro ≤1, the disease-free steady solution is globally asymptotically stable and the disease always dies out. If Ro >1, there exists a unique endemic equilibrium which is globally stable and the disease persists. Application is done on data from Western Kenya. The age structure reduces the level of infection and the populations settle to the equilibrium faster than in the model without age structure.
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