A mobility model for classical swine fever in feral pig populations

We present a simulation model which explicitly captures the movement of wild animals overthe landscape and the effect which herd mobility has on the temporal and spatial course of an epidemic.Using the example of classical swine fever in feral pig populations in the tropical savannas, we demonstratethat seasonal factors influencing population density and movement patterns are an important factor in thetransmission of the disease. Pig population density is much greater at the start of the dry season than at thestart of the wet season, with an epidemic most likely to occur if initiated at the start of the dry season. Spatialheterogeneity due to scarcity of water in the dry season causes herds to congregate around water sources.This concentration of herds, and the consequential isolation of sub-populations, reduces overall diseasetransmission compared with a model where the population is more evenly distributed over the landscape.The presence of adult male pig herds, which travel over greater distances than family herds, is shown toincrease the overall scale of an outbreak in the dry season by connecting together otherwise isolated familyherds. Eradication strategies are more likely to be successful in the dry season if they target long-range adultmale herds. Our simulation method is generic and is equally applicable to other diseases where the hostspecies is mobile.