Wolbachia infection in a sex-structured mosquito population carrying West Nile virus

TL;DR

This paper develops a mathematical model to study Wolbachia-infected mosquito populations, examining their stability and potential to control West Nile virus transmission, highlighting the importance of Wolbachia in disease eradication.

Contribution

The paper introduces a comprehensive sex-structured model incorporating Wolbachia effects and extends it to include West Nile virus dynamics, providing insights into disease control strategies.

Findings

Multiple stable equilibria including Wolbachia-dominated states

Wolbachia infection can lead to West Nile virus eradication under certain conditions

Increased Wolbachia transmission reduces West Nile virus spread

Abstract

Wolbachia is possibly the most studied reproductive parasite of arthropod species. It appears to be a promising candidate for biocontrol of some mosquito borne diseases. We begin by developing a sex-structured model for a Wolbachia infected mosquito population. Our model incorporates the key effects of Wolbachia infection including cytoplasmic incompatibility and male killing. We also allow the possibility of reduced reproductive output, incomplete maternal transmission, and different mortality rates for uninfected/infected male/female individuals. We study the existence and local stability of equilibria, including the biologically relevant and interesting boundary equilibria. For some biologically relevant parameter regimes there may be multiple coexistence steady states including, very importantly, a coexistence steady state in which Wolbachia infected individuals dominate. We also extend the model to incorporate West Nile virus (WNv) dynamics, using an SEI modelling approach. Recent evidence suggests that a particular strain of Wolbachia infection significantly reduces WNv replication in Aedes aegypti. We model this via increased time spent in the WNv-exposed compartment for Wolbachia infected female mosquitoes. A basic reproduction number $R_0$ is computed for the WNv infection. Our results suggest that, if the mosquito population consists mainly of Wolbachia infected individuals, WNv eradication is likely if WNv replication in Wolbachia infected individuals is sufficiently reduced.