Habitat-Mediated Spillover Risk of Andes Hantavirus in Oligoryzomys longicaudatus: A Mechanistic Eco-Epidemiological Model

Andes hantavirus (ANDV) is a rodent-borne orthohantavirus associated with hantavirus cardiopulmonary syndrome in southern South America. Its maintenance and spillover risk depend on the ecology of its principal reservoir, Oligoryzomys longicaudatus, and on environmental changes that alter habitat availability, host abundance, and human-rodent interfaces. We developed a mechanistic eco-epidemiological model that couples effective habitat cover to an SIR framework for ANDV transmission in O. longicaudatus. Habitat degradation and compensatory restoration modify rodent carrying capacity, natality, and the force of infection, which depends on infected host load relative to instantaneous ecological capacity. We derived the habitat equilibrium, the basic reproduction number R₀, and the time-dependent effective reproduction number R_e(t), and evaluated infection-burden and threshold indicators across degradation-restoration scenarios. The analysis shows that R₀ is independent of equilibrium habitat cover because susceptible abundance scales with carrying capacity at the disease-free equilibrium. In contrast, R_e(t), cumulative incidence, and infected load depend on transient habitat-mediated crowding. Restoration increases reservoir abundance and absolute infection burden, whereas degradation can reduce abundance while increasing crowding-driven transmission pressure and prolonging supercritical windows. These results identify ecological conditions under which habitat change may intensify reservoir infection pressure and guide One Health surveillance at human-rodent interfaces.