1. Spatial epidemiology, ecology and control of vampire bat rabies

Interventions to control infectious diseases of wildlife that affect human or domestic animal health often seek to control or eliminate the pathogen from its wildlife reservoir using culling or vaccination. While such efforts are intuitive in theory and offer the seductive possibility of a permanent solution, implementation is notoriously difficult and controversial. Poor understanding of what drives pathogen transmission in wildlife can even lead such interventions to be counterproductive for disease control.

In Latin America, vampire bat–transmitted rabies virus represents a key example of how such uncertainty can impede efforts to prevent cross-species transmission. Despite decades of bat culling programs, agricultural and human health losses remain surprisingly high. These limitations seem to arise from the more general problem of how to design control strategies for pathogens that persist through spatial processes in wild or free-ranging animal populations. In projects funded by the Wellcome Trust and Royal Society, we are combining longitudinal surveillance of vampire bat colonies, bat population genetics, viral genomics and epidemiological time series data to improve anticipation of outbreaks and develop a scientific basis for interventions.

This work has revealed key findings of relevance to control programs.

– Rabies exposures in bats are independent of colony sizes (Streicker et al. 2012 Proc Roy Soc B)
– Culling bats appears either ineffective or counter productive for rabies control (Streicker et al. 2012 Proc Roy Soc B)
– Persistence relies on high rates of bat dispersal and frequent immunizing infections (Blackwood et al. 2013 PNAS)
– For culling to have a chance at being effective, it must be spatially coordinated across large geographic scales (Blackwood et al. 2013 PNAS)

Main collaborators Julio Benavides (Glasgow), William Valderrama (ILLARIY), Carlos Shiva (UPCH), Nestor Falcon (UPCH), Katie Hampson (Glasgow)

Funding from: Wellcome Trust, Royal Society


2. Intervention strategies for vampire bat rabies

We want to understand how to improve control of vampire bat rabies within the bat reservoir. This means understanding why existing control efforts like culling have limited success for preventing rabies and considering whether alternatives such as oral vaccination could be more effective. Ongoing research on this topic is evaluating how large scale culling programs affect bat population dynamics, frequency of spillover infections to livestock and the spatial spread of rabies within vampire bats. Another project is using field experiments with biomarkers and mathematical models to evaluate how topically transmitted oral rabies vaccines could spread among bats by grooming and whether the herd immunity achieved would be enough to stop rabies outbreaks in bats, thereby protecting people.

Main collaborators Julio Benavides (Glasgow), William Valderrama (ILLARIY), Kevin Bakker (University of Michigan), Tonie Rocke (USGS), Jorge Osorio (University of Wisconsin), Regional Government of Apurimac.

Funding from: Royal Society Challenge Grants

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