Disease-emergence dynamics and control in a socially-structured wildlife species

Abstract

Once a pathogen is introduced in a population, key factors governing rate of spread include contact structure, supply of susceptible individuals and pathogen life-history. We examined the interplay of these factors on emergence dynamics and efficacy of disease prevention and response. We contrasted transmission dynamics of livestock viruses with different life-histories in hypothetical populations of feral swine with different contact structures (homogenous, metapopulation, spatial and network). Persistence probability was near 0 for the FMDV-like case under a wide range of parameter values and contact structures, while persistence was probable for the CSFV-like case. There were no sets of conditions where the FMDV-like pathogen persisted in every stochastic simulation. Even when population growth rates were up to 300% annually, the FMDV-like pathogen persisted in <25% of simulations regardless of transmission probabilities and contact structure. For networks and spatial contact structure, persistence probability of the FMDV-like pathogen was always <10%. Because of its low persistence probability, even very early response to the FMDV-like pathogen in feral swine was unwarranted while response to the CSFV-like pathogen was generally effective. When pre-emergence culling of feral swine caused population declines, it was effective at decreasing outbreak size of both diseases by ≥80%.

Ecological drivers of African swine fever virus persistence in wild boar populations: Insight for control

“…A recent study found that for wild boar, a social species that aggregates in family groups (Podgórski, Lusseau, et al, ; Podgórski, Scandura, et al, ), spatially targeted culling that focuses on removing all members of family groups is more effective than random removal of individuals (Pepin & VerCauteren, ). Although this simulation model did not account for movement responses due to culling, it did include effects of social structuring in disease transmission.…”

Contact rates in wild boar populations: Implications for disease transmission

“…Effect of these constraints on disease spread across the population will depend on pathogen characteristics, such as transmission route, infectiousness, incubation time, lethality. We can expect highly virulent pathogens with short infectious periods to spread rapidly within groups but have limited population‐level effects, particularly in fragmented or low‐density populations (Ward et al , Pepin and VerCauteren ).…”

“…Because different factors may act on each level of social organization (Vander Wal et al ), a hierarchical approach combining analysis of dyadic associations and network‐based metrics, as adopted in our study, offers full understanding of the factors influencing contact heterogeneity (Pepin et al , Vander Wal et al ). Information about contact rates and structure in wildlife populations can be used to parameterize epidemiological models (Craft et al , Pepin and VerCauteren ) and inform disease management to optimize targeted control actions (Grear et al , Hirsch et al ).…”

Ecological drivers of African swine fever virus persistence in wild boar populations: insight for control

“…A recent study found that for wild boar, a social species that aggregates in family groups (Podgórski et al 2014a, Podgórski et al 2014b), spatially-targeted culling that focuses on removing all members of family groups is more effective than random removal of individuals (Pepin & VerCauteren 2016). Although this simulation model did not account for movement responses due to culling, it did include effects of social structuring in disease transmission.…”