Management of Sylvatic Plague, (Yersinia pestis) in Prairie Dogs (Cynomys spp.): Research Updates
American Association of Zoo Veterinarians Conference 2010

Julia Rodriguez-Ramos Fernandez1, Lic.Vet; Susan R. Smith2, BS; Judy L. Williamson2, MS; Willy Berlier1, PhD; Tonie E. Rocke2, PhD

1Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI, USA; 2USGS-National Wildlife Health Center, Madison, WI, USA

Read the Spanish translation: Control de la Peste Selvática en Perritos de las Praderas: Últimos Avances


Plague, a zoonotic disease caused by the bacteria Yersinia pestis (Fam. Enterobacteriaceae) entered the United States more than 100 years ago.1,4 Prairie dogs (Cynomys spp.) and other rodents such as ground squirrels serve as epizootic hosts and suffer high rates of mortality, but true enzootic hosts are still unidentified in many ecosystems.1-3 Prairie dogs are a keystone species in prairie ecosystems, and their loss affects other species, such as the endangered black-footed ferret (Mustela nigripes).5 Vector control, although successful in controlling outbreaks, is labor intensive, costly, and often applied too late to be effective. Oral vaccination of prairie dogs against plague could provide a feasible alternative. Laboratory challenge studies have shown that oral vaccination of prairie dogs using a recombinant raccoon poxvirus expressing plague antigens provides significant protection against Y. pestis challenges that simulated simultaneous delivery of plague bacteria by numerous flea bites.6 Before field application is considered, a delivery bait that is palatable to prairie dogs, resistant to environmental conditions, and capable of maintaining vaccine titer must be selected, along with an appropriate biomarker to evaluate uptake by animals. In our latest studies, we tested bait candidates, determined that peanut butter was the preferred bait flavor, and found that consumption of vaccine-laden baits resulted in protection from plague challenge. We also demonstrated that rhodamine B included in baits at a concentration of 0.25% is a safe and effective systemic marker in prairie dogs, providing a simple and reliable method to monitor oral vaccine uptake in future field trials.

Literature Cited

1.  Antolin, M.F., D.E. Biggins, and P. Gober. 2010. Symposium on the ecology of plague and its effects on wildlife: a model for translational research. Vector Borne Zoonotic Diseases. 10:3–5.

2.  Cully, J.F., and E.S. Williams. 2001. Interspecific comparisons of sylvatic plague in prairie dogs. Journal of Mammalogy. 82:894–905.

3.  Gage, K.L., and M.Y. Kosoy. 2005. Natural history of plague: perspectives from more than a century of research. Annu Rev Entomol. 50:505–528.

4.  Gasper, P.W., and R.P. Watson. 2001. Plague and yersiniosis. In: Williams E.S., and I.K. Barker (eds.). Infectious Diseases of Wild Mammals. 3rd ed. Iowa State Press, Iowa. 313–329.

5.  Kotliar, N.B., B.J. Miller, R.P. Reading, and T.W. Clark. 2006. The prairie dog as a keystone species. In: Hoogland, J.L. (ed.). Conservation of the Black-Tailed Prairie Dog: Saving North America’s Western Grassland. Island Press, Washington, DC. 53–64.

6.  Rocke, T.E., N. Pussini, S.R. Smith, J. Williamson, B. Powell, and J.E. Osorio. 2010. Consumption of baits containing raccoon pox-based plague vaccines protects black-tailed prairie dogs (Cynomys ludovicianus). Vector Borne Zoonotic Diseases. 10:53–58.


Speaker Information
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Julia Rodriguez-Ramos Fernandez, Lic.Vet
Department of Pathobiological Sciences
School of Veterinary Medicine
University of Wisconsin
Madison, WI, USA

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