  Vector-borne diseases with reservoir cycles are complex to understand because
new infections come from contacts of the vector with humans and different
reservoirs. In this scenario, the basic reproductive number $\mathcal{R}^h_0$
of the system where the reservoirs are not included could turn out to be less
than one, yet, an endemic equilibrium be observed. Indeed, when the reservoirs
are taken back into account, the basic reproductive number $\mathcal{R}_0^r$,
of only vectors and reservoirs, explains the endemic state. Furthermore,
reservoirs cycles with a small basic reproductive number could contribute to
reach an endemic state in the human cycle. Therefore, when controlling for the
spread of a disease, it could not be enough to focus on specific reservoir
cycles or only on the vector. In this work, we created a simple epidemiological
model with a network of reservoirs where $\mathcal{R}_0^r$ is a bifurcation
parameter of the system, explaining disease endemicity in the absence of a
strong reservoir cycle. This simple model may help to explain transmission
dynamics of diseases such as Chagas, Leishmaniasis and Dengue.
