Reports of deer, pronghorns infections climb in southeast Montana

State wildlife biologists in southeast Montana have seen an increase this fall in epizootic hemorrhagic disease (EHD) and blue tongue virus (BTV) reports in white-tailed deer and pronghorns along the Yellowstone River and in prairie habitats.

These cases are suspect but have not yet been confirmed through lab testing, according to Montana Fish, Wildlife & Parks.

EHD and BTV are hemorrhagic diseases caused by slightly different viruses but have very similar clinical signs. Both 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 typi