Abstract
In this paper, a deterministic mathematical model for Dengue Fever (DF) and Zika virus (ZIKV) co-infection transmission dynamics is formulated and analyzed. Two sub-models, namely ZIKV-only and DF-only sub-models, are considered first of all. Rigorous qualitative analysis of the sub-models reveals that each of the diseases undergoes the phenomenon of backward bifurcation when the associated reproduction number of both ZIKV-only and DF-only submodels (denoted by R-0z(+) and R-0d respectively) is less than unity. It is shown, using the centre manifold theory that the full ZIKV-DF co-infection model undergoes a backward bifurcation phenomenon. In addition, simulation of the full ZIKV-DF model shows the clear picturization of disease transmission and also we provide the solution of model numerically in detail.