# Competent hosts and endemicity of multi-host diseases

## TL;DR

This paper introduces a method to analyze how biodiversity impacts vector-borne disease dynamics, revealing that competent hosts are essential for endemicity and that increasing their density can amplify disease prevalence.

## Contribution

It provides a mathematical framework to understand the role of competent hosts in the persistence of endemic vector-borne diseases under frequency-dependent transmission assumptions.

## Key findings

- Presence of a competent host is necessary for endemic disease.
- Increasing competent host density amplifies disease prevalence.
- Frequency-dependent transmission influences disease dynamics.

## Abstract

In this paper we propose a method to study a general vector-hosts mathematical model in order to explain how the changes in biodiversity could influence the dynamics of vector-borne diseases. We find that under the assumption of frequency-dependent transmission, i.e. the assumption that the number of contacts are diluted by the total population of hosts, the presence of a competent host is a necessary condition for the existence of an endemic state. In addition, we obtain that in the case of an endemic disease with a unique competent and resilient host, an increase in its density amplifies the disease.