Minnesota animal officials have confirmed the first cases of a disease that inflicts "quick, suspicious deaths" on deer.
Six out of seven animals in a herd of white-tailed deer in Goodhue County, southeast Minnesota, died from Epizootic Hemorrhagic Disease (EHD) earlier this month.
Their deaths had been reported by the herd's owner, who was alarmed by what they described as their "quick and suspicious" demise.
The seventh deer hasn't shown any signs of the disease, with this the first detection of EHD in deer in Minnesota, albeit it's widespread across North America, and was detected in two cattle in 2012 and 2013.
"This virus is transmitted between deer by biting midges, or gnats, which are most active in the fall before they are killed by the first frost of the season," said Dr. Mackenzie Reberg, The Minnesota Board of Animal Health senior veterinarian.
"These bugs can’t travel far on their own and we’re concerned by this detection because the herd owner hasn’t moved deer onto the property for several years."
EHD doesn't pose any health risks to people, but many deer species may be infected with it, and white-tailed deer in particular are highly susceptible, "and experience high rates of mortality."
Most die within 36 hours, the Board of Animal Health said, and symptoms can include fever, anorexia, lethargy, respiratory distress and severe swelling of the head or neck.
There's no treatment or vaccine available.