  This article is aimed at proposing a generalization of the Ross-Macdonald
model for the transmission of Vector-borne diseases in which human-to-human
contagions are also considered. We first present this generalized model by
formulating a mean field theory, checking its validity by comparing to
numerical simulations. To make the premises of our model more realistic, we
adapt the mean field equations to the case in which human contacts are
described by a complex network. In this case we are also able to derive an
analytical expression for the epidemic threshold. In both the mean-field and
network-based models, we estimate the value of the epidemic threshold which
corresponds to the boundary between the disease-free and epidemic regimes. The
expression of this threshold allows us to discuss the impact that
human-to-human contagions have on the spread of vector-borne diseases.
