Modeling vaccination strategies as a management tool for sylvatic plague in prairie dog populations in the western USA

Sylvatic plague, caused by the bacterium Yersinia pestis, often causes large epizootics and population extirpation in prairie dogs and other ground squirrels in the western United States. This causes significant problems for... [ view full abstract ]

Sylvatic plague, caused by the bacterium Yersinia pestis, often causes large epizootics and population extirpation in prairie dogs and other ground squirrels in the western United States. This causes significant problems for management agencies who want to maintain prairie dog populations that can support reintroduced black-footed ferrets, a highly endangered mammal that preys solely on prairie dogs. Recently, an ingestible sylvatic plague vaccine was developed and proven effective in laboratory studies. Here, we develop an individual based spatially explicit model of plague dynamics that is based on the output of spatial mark-recapture models to estimate spatial distributions of prairie dogs within colonies and their local movement patterns. We then used this model to simulate potential oral vaccination applications and their effectiveness in protecting prairie dog populations from plague outbreaks. We found that the probability of a plague epizootic occurring decreased with increasing effective vaccination levels. We provide recommendations for future vaccination strategies for prairie dog colonies based on two management goals, to maintain occupancy (i.e. vaccination levels needed to reduce mortality from epizootics) and to provide herd immunity (i.e. vaccination levels needed to prevent disease colonization).