Surveillance for sylvatic plague (Yersinia pestis) was conducted near Meeteetse, Wyoming (USA) from 24 May to 14 June 1985. Ten species of fleas were collected from white-tailed prairie dogs (Cynomys leucurus), and from their burrows and associated rodents. Five of these flea species and two adult prairie dogs were positive for plague. The progression of this plague epizootic appeared to be slower and the intensity was less than in previous epizootics in other prairie dog colonies. The plague epizootic occurred within the only known colony of black-footed ferrets (Mustela nigripes) and was a potential threat to the food source of this endangered species.
