An Immuno-Epidemiological Vector-Host Model with Within-Vector Viral Kinetics

TL;DR

This paper develops a comprehensive vector-host disease model incorporating within-vector and within-host viral dynamics, providing insights into disease stability and implications for control strategies.

Contribution

It introduces a novel coupled model integrating within-vector and within-host viral kinetics with feedbacks across scales, advancing understanding of disease dynamics.

Findings

The basic reproduction number $\\mathcal R_0$ determines stability of disease-free and endemic states.

The model shows conditions for local and global stability based on $\mathcal R_0$.

Numerical results highlight the importance of within-vector viral kinetics in epidemic outcomes.

Abstract

A current challenge for disease modeling and public health is understanding pathogen dynamics across scales since their ecology and evolution ultimately operate on several coupled scales. This is particularly true for vector-borne diseases, where within-vector, within-host, and between vector-host populations all play crucial roles in diversity and distribution of the pathogen. Despite recent modeling efforts to determine the effect of within-host virus-immune response dynamics on between-host transmission, the role of within-vector viral dynamics on disease spread is overlooked. Here we formulate an age-since-infection structured epidemic model coupled to nonlinear ordinary differential equations describing within-host immune-virus dynamics and within-vector viral kinetics, with feedbacks across these scales. We first define the \emph{within-host viral-immune response and within-vector viral kinetics dependent} basic reproduction number $\mathcal R_0.$ Then we prove that whenever $\mathcal R_0<1,$ the disease free equilibrium is locally asymptotically stable, and under certain biologically interpretable conditions, globally asymptotically stable. Otherwise if $\mathcal R_0>1,$ it is unstable and the system has a unique positive endemic equilibrium. In the special case of constant vector to host inoculum size, we show the positive equilibrium is locally asymptotically stable and the disease is weakly uniformly persistent. Furthermore numerical results suggest that within-vector-viral kinetics and dynamic inoculum size may play a substantial role in epidemics. Finally, we address how the model can be utilized to better predict the success of control strategies such as vaccination and drug treatment.