Deer from a private herd on a farm in southeast Minnesota have been struck with a virus carried by biting flies that causes rapid death from internal bleeding — the first time the disease has been seen in any of the state's deer population.
Officials from the Minnesota Board of Animal Health said the virus, epizootic hemorrhagic disease (EHD), was confirmed in seven deer on the Goodhue County farm. Six died, but one buck appears healthy and shows no sign of the disease.
There is no indication that the virus is present in any of the state's wild deer population, said Minnesota wildlife officials, and the risk now is likely low because the small biting flies that carry it die off after the first frost or two.
Nonetheless, its appearance is concerning enough for state wildlife officials to ask the public and law enforcement to keep an eye out for suspicious deer deaths.
"It looks pretty ugly because a lot die in a short time and near water," said Lou Cornicelli, wildlife manager for the Minnesota Department of Natural Resources.
How the disease got to Minnesota is unknown. Board senior veterinarian Mackenzie Reberg said midges don't fly far, but they can be carried long distances by the wind.
"We're concerned by this detection because the herd owner hasn't moved deer onto the property for several years," she said.
Cornicelli said that it's also possible that someone who visited or works at the farm might have unknowingly carried insects there.
Animal health board officials said the quick and suspicious deaths of the animals alarmed the owner, who worked with a veterinarian to submit tissues from the carcasses to the Iowa State University Veterinary Diagnostic Laboratory for investigation and confirmation.
Though this is the first time it's been detected in deer in Minnesota, the disease is widespread in other states, particularly in the south, but also in Wisconsin, Iowa and the Dakotas. It has also twice before been identified in cattle in southern Minnesota, once in Brown County in 2012, and once in Murray County in 2013.
There are no known health risks to humans, and no vaccine or other treatment available for infected animals.
Many hoofed species may be infected with EHD, but white-tailed deer are highly susceptible and experience high rates of mortality. Most die within 36 hours of showing clinical signs, which can include fever, anorexia, lethargy, stiffness, respiratory distress, oral ulcers and severe swelling of the head and neck.
Outbreaks in deer in northern states can be much worse than those in the south, most likely because the disease is less common and the herds have less immunity, wildlife experts said.
While an outbreak can have a short-term impact on a deer population, it's unlikely to cause a long-term drop in numbers, Cornicelli said.
