An Epizootic of Plague in Gunnison's Prairie Dogs (Cynomys Gunnisoni) in South‐Central Colorado

Abstract

In June 1964 and epizootic of plague began in Gunnison's prairie dogs (Cynomys gunnisoni) in Cochetopa Park, Saguache County, Colordo. Seven colonies of prairie dogs were known in the area at that time. By the end of the summer, 2 of these colonies were exterminated and several others were greatly decimated. A residual phase of the epizootic continued through the summer of 1965 and terminated in 1966 leaving only a few prairie dogs in 2 colonies. No evidence was obtained to indicate that the populations of other mammals living in the area wer adversely affected by plague. The mammalian reservoir of plague in this area remains unknown, but the data suggest that small mammals such as the deer mouse (Peromyscus maniculatus) and the golden—mantled ground squirrel (Citellus lateralis) may be involved. The spread of infection from prairie dog to prairie dog is via flea vectors, especially Opisocrostis tuberculatus, O. labis, and Oropsylla idahoensis. The vector responsible for getting the initial infection into the prairie dogs from some reservoir source is unknown. Apparently, the transfer of Pasteurella pestis from a mammalian reservoir into a population or prairie dogs is an improbable event, and this improbability, rather than any resistance to infection, or resistance to disease, by the prairie dogs is a major factor which allows them to live in such areas of plague enzooticity.