An epizootic of besnoitiosis in captive caribou (Rangiger tarandus caribou), reindeer (Rangifer tarandus tarandus) and mule deer (Odocoileus hemionus hemionus)

Besnoitia was diagnosed in 2 caribou (Rangifer tarandus caribou) which died of pneumonia at the Assiniboine Park Zoo, Winnipeg, Manitoba, Canada, in 1983. During the following 3 years, besnoitiosis spread to an isolated herd of caribou, to mule deer (Odocoileus hemionus hemionus) and to reindeer (R. tarandus). Reduction of exposure to biting insects appears to have reduced the transmission of besnoitiosis within the reindeer herd. The morbidity rate was approximately 82% in caribou and 67% in mule deer over the age of 2 months. Most animals with clinical signs were euthanized; this precluded an estimation of the disease-related mortality rate. Twenty-eight caribou, 10 mule deer and 3 reindeer were euthanized or died as a result of this epidemic. Attempts to artificially transmit the disease to potentially susceptible intermediate and definitive hosts were unsuccessful.