An Immuno-Epidemiological Model of Foot-and-Mouth Disease (FMD) in the African Buffalo Population with Carrier Transmission

Foot-and-mouth disease (FMD) is a highly contagious disease that spreads among cloven-hoofed animals. Although not deadly, FMD can cause major delays in meat and dairy production. One major concern is that the foot-and-mouth disease virus (FMDV) can persist in African buffalo hosts as natural reservoirs for long periods of time, causing the pathogens to reemerge in susceptible populations. In this paper, we present a novel immuno-epidemiological model of FMD in the African buffalo host populations. Upon infection, the hosts can undergo two phases, namely the acute and the carrier stages. In our model, we divide the infectious population based upon these two stages so that we can dynamically capture the immunological characteristics of both phases of the disease to better understand the carriers role in disease transmission. We first define the within-host viral-immune kinetics dependent epidemiological basic reproduction number[R] 0 and show that it is a threshold condition for the local stability of the disease-free equilibrium and existence of the endemic equilibrium. We also analytically show that the system always displays forward bifurcation with respect to between-host epidemic parameters. Later, by using a sensitivity analysis (SA) approach developed for multi-scale models, we assess the impact of the acute infection and carrier phase immunological parameters on[R] 0. Interestingly, our numerical results show that the within-carrier infected host immune kinetics parameters and the susceptible individual recruitment rates play significant roles in disease persistence, which are consistent with experimental and field studies.