FWP wildlife biologists in southeast Montana’s Region 7 have seen an increase this fall in epizootic hemorrhagic disease (EHD) and blue tongue virus (BTV) reports in white-tailed deer and antelope along the Yellowstone River corridor and out in prairie habitats. These cases are suspect but have not yet been confirmed through lab testing.

EHD and BTV are hemorrhagic diseases that are caused by slightly different viruses but have very similar clinical signs. Both EHD and BTV are spread by tiny flies called midges, commonly called “no-see-ums.” Infections typically increase in late summer and fall during warm, dry conditions when flies are most abundant, and deer are often concentrated near water. Periods of outbreak usually end after a hard frost. Deer and antelope with EHD or BTV typically die within eight to 36 hours after showing symptoms. This disease is not spread between deer and there is no known risk to humans. However, it is recommended that hunters not consume the meat of animals that appear to be sick.

For hunters planning on hunting white-tailed deer or antelope around the Yellowstone River this hunting season, please be aware deer densities may be lower than normal due to the localized impacts of EHD or BTV. To help us monitor this outbreak, please report sick and dead deer and antelope to the wildlife manager, Brett Dorak, at brett.dorak@mt.gov, or (406)-234-0921.

Animals with EHD or BTV can appear weak, lethargic and disoriented. They are often found near water sources due to high fever and may drool or foam at the mouth. They can exhibit swelling of the head, neck, tongue and lips, as well as mouth sores. The tongue may appear blue. EHD and BTV are typically fatal, but some deer and antelope survive and develop immunity.