| Abstract: |
| Dengue fever is among the most prevalent vector-borne diseases worldwide. In this work, we propose and analyze a deterministic two-strain host-vector model for dengue transmission. The human population is structured into primary and secondary infection classes, while the mosquito population is divided into single- and co-infected compartments. The model incorporates temporary cross-immunity, mortality during secondary infections, antibody-dependent enhancement (ADE), and explicit mosquito co-infection. ADE is represented through distinct transmission rates for primary and secondary infections. Using the next-generation matrix approach, we derive the basic reproduction number, R_0, and establish the local stability of the disease-free equilibrium when R_0<1. We show that specific ADE conditions can destabilize one-strain endemic equilibria, enabling invasion by a heterologous strain. Center-manifold analysis and numerical continuation further reveal backward bifurcation, bistability, and Hopf-induced oscillations, emphasizing complex dynamics relevant to dengue control strategies. |
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