Resistance to Plague Among Black-Tailed Prairie Dog Populations

Abstract

In some rodent species frequently exposed to plague outbreaks caused by Yersinia pestis, resistance to the disease has evolved as a population trait. As a first step in determining if plague resistance has developed in black-tailed prairie dogs (Cynomys ludovicianus), animals captured from colonies in a plague-free region (South Dakota) and two plague-endemic regions (Colorado and Texas) were challenged with Y. pestis at one of three doses (2.5, 250, or 2500 mouse LD50s). South Dakota prairie dogs were far more susceptible to plague than Colorado and Texas prairie dogs ( p < 0.001), with a mortality rate of nearly 100% over all doses. Colorado and Texas prairie dogs were quite similar in their response, with overall survival rates of 50% and 60%, respectively. Prairie dogs from these states were heterogenous in their response, with some animals dying at the lowest dose (37% and 20%, respectively) and some surviving even at the highest dose (29% and 40%, respectively). Microsatellite analysis revealed that all three groups were distinct genetically, but further studies are needed to establish a genetic basis for the observed differences in plague resistance.

Differential plague susceptibility in species and populations of prairie dogs

“…All animals were housed in NWHC's BioSecurity Level‐3 animal isolation facility, and all animal protocols were approved by NWHC's animal care and use committee. Briefly, all prairie dogs were treated and housed similarly in every experiment (See Rocke et al, for details). Before transfer to NWHC, they were dusted with carbaryl and upon arrival examined for parasites and treated with an anthelminthic (Ivermectin) and Imidacloprid for additional flea control; the prairie dogs were gang‐housed on the floor with custom‐made stainless‐steel nest boxes and PVC pipes for refugia.…”

“…Although mass mortality is common in prairie dogs during plague outbreaks, lowered susceptibility to plague has been observed in some populations of prairie dogs. For example, Rocke et al () noted differential survival rates in experimentally challenged black‐tailed prairie dogs ( Cynomys ludovicianus ), with animals from Texas and Colorado surviving at higher rates compared with animals from South Dakota where plague had not occurred previously. Pauli, Buskirk, Williams, and Edwards () also noted that black‐tailed prairie dogs were capable of surviving plague outbreaks and regrouping into new coteries.…”

“…Yersinia pestis challenge studies have been ongoing at the U.S. Geological Survey National Wildlife Health Center (USGS NWHC) to support the development of a bait‐delivered sylvatic plague vaccine (SPV) for prairie dogs (e.g., Rocke et al, ; Rocke, Smith, Stinchcomb, & Osorio, ; Rocke et al, ). We consolidate data from control animals (plague inoculated but not vaccinated) across studies to evaluate relative plague susceptibility between study populations and to determine whether our data provide support for the idea that prairie dogs can develop some level of resistance to plague.…”

Climatic and evolutionary drivers of phase shifts in the plague epidemics of colonial India

“…Existing animal-based plague surveillance programs monitor die offs and seroprevalence in rodent populations for early warning signs of the disease's incursion (91,92). However, expansions of resistance among hosts during epizootics could offset population declines and diminish the utility of serology as a marker for local plague transmission (27,64,71,93). The diverse mammal species that may serve as plague hosts further complicate surveillance and control strategies.…”

Effects of prey metapopulation structure on the viability of black‐footed ferrets in plague‐impacted landscapes: a metamodelling approach

“…; Rocke et al . ), this process is not yet well understood and was not included in this model. Detailed output data from Outbreak were used to generate three summary statistics that were subsequently used for modelling prairie dog metapopulation dynamics: (i) overall survival rate in a plague outbreak year, (ii) probability of a potential disperser individual being a carrier of plague and (iii) the probability of a single infected individual initiating an epizootic (Appendix S2).…”