Although these viruses can infect a wide variety of ruminants, susceptibility varies among species. HD principally affects white-tailed deer and mule deer, but disease has been reported in other North American ungulates.

Clinical disease due to BTV has been reported in white-tailed deer, mule deer, black deer, pronghorn, bighorn sheep, and possibly mountain goats. Clinical disease due to EHDV has been reported in white-tailed deer, mule deer, bighorn sheep, and pronghorn. BTV and/or EHDV have been isolated from and/or antibodies detected in other wild North American ruminant species without disease. Clinical disease due to BTV also has been reported in a variety of ungulate species in zoological collections.

It has been suggested that BTV may have been partially responsible for the disappearance of bighorn sheep from west Texas because the BHS population declined appreciably at a time when bluetongue was rampant in domestic sheep on the same range.

Antibodies to BTV have been reported from several free-ranging ungulate species in Africa, but disease due to infection has only been suspected in one case. A die-off of topi’s in Uganda was suspected to be due to BTV but this was never confirmed. Little is known about EHDV in wildlife outside North America. Antibodies to BTV, but not disease, have been reported in wild carnivores in Africa. These carnivores may have been infected through predation or scavenging of BTV infected ungulates.

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