A new oral vaccine bait can help protect prairie dogs against sylvatic plague and possibly assist in the recovery of black-footed ferrets, one of the most endangered mammals in North America.
Sylvatic plague is devastating to prairie dogs and the endangered black-footed ferret, a prairie dog–dependent species. (Courtesy of the U.S. Fish and Wildlife Service)
Sylvatic plague, a bacterial disease caused by Yersinia pestis, affects numerous wild and domestic animal species as well as humans. Developed specifically for prairie dogs by scientists at the U.S. Geological Survey's National Wildlife Health Center and the University of Wisconsin-Madison, the peanut butter–flavored vaccine elicits a protective immune response that can help vaccinated prairie dogs fight off infection after later exposure to the disease.
"Plague is devastating to prairie dogs, a keystone species of grassland ecosystems," said Tonie Rocke, PhD, a USGS scientist and the project lead. "Our goal in developing an oral plague vaccine is to provide another tool for land managers to reduce the effects of plague outbreaks on prairie dog colonies. This reduction could have positive impacts on conservation of the threatened Utah prairie dog and survival of the endangered black-footed ferret, a prairie dog–dependent species."
The current method for controlling plague consists of dusting prairie dog colonies with insecticide to kill fleas that transmit the pathogen. Although effective in controlling the spread of plague, dusting is labor-intensive, and some flea species may develop resistance to the pesticide.
Between 2013 and 2015, a consortium of 14 federal, state, tribal, and nongovernmental agencies worked together to field-test the plague vaccine in all four prairie dog species present across Arizona, Colorado, Montana, South Dakota, Texas, Utah, and Wyoming. The agencies' findings, published as a USGS study in the journal EcoHealth this past June (http://jav.ma/Plague_1), showed prairie dog survival rates were higher on vaccine-treated plots during plague outbreaks than on plots that received placebo baits, suggesting that consumption of vaccine baits provided protection for prairie dogs.
Researchers anticipate that application of vaccine baits to larger prairie dog complexes on an annual basis will enhance protection against plague.
Colorado Parks and Wildlife conducted the initial field trials that demonstrated vaccine-laden baits could be used safely with no adverse effects for nontarget species, such as small mammals, and has been instrumental in furthering large-scale vaccine and bait production for use by wildlife managers. In a companion paper (http://jav.ma/plague_2) also published in EcoHealth, CPW demonstrated that treating prairie dog colonies annually with a flea-control dust or the oral vaccine can prevent population collapse resulting from plague.
"Wildlife managers have struggled to recover ferrets and manage prairie dog colonies due to the devastating effects of plague," said Dan Tripp, a CPW scientist and a co-author of the USGS study. "It is our hope that use of the sylvatic plague vaccine in select areas, with the support of willing landowners, will help to limit the impact of plague to wildlife."