Minnesota's mysterious run as a Midwestern state ostensibly free of a deadly deer virus has come to an end with lab confirmation that a group of wild whitetails in central Minnesota were stricken by epizootic hemorrhagic disease (EHD).
The outbreak in Stearns County is believed to have killed up to 20 or more deer. Only two carcasses suitable for testing and tissue samples from both deer tested positive at National Veterinary Services Laboratories in Ames, Iowa. The Minnesota Department of Natural Resources announced the results Wednesday morning.
"All of our neighboring states have been dealing with EHD for years,'' said DNR Wildlife Research Manager Lou Cornicelli. "So it was alwats a question of whien it would show up in Minnesota.''
The rapidly progressing disease is carried by biting midges, also known as gnats and no-see-ums. It isn't contagious from deer to deer and the seasonal risk goes away after the first frost, but EHD has potential to significantly reduce local deer populations on a short-term basis, state wildlife officials said.
Just one week ago, the Minnesota Board of Animal Health said EHD killed two farmed deer in Houston County. The owner submitted samples because of their suspicious deaths. The virus first showed up on a Minnesota deer farm last year, killing six animals. But wildlife researchers have never detected an outbreak in the state's wild herd.
"There's no good reason why it hasn't shown up here before,'' Cornicelli said.
Cornicelli said the DNR urges public reporting of deer deaths, especially when numbers of deer die in proximity to each other for unexplained reasons. Deer stricken by EHD often die near water because fevers caused by the disease make them thirsty.
The agency was alerted to 12 to 20 dead deer at different Morrison and Stearns County sites over Labor Day weekend. On Tuesday after Labor Day, DNR crews found eight to 12 carcasses. The agency said the two dead deer that tested positive for EHD were found in the St. Stephen area.
The agency also checked out a separate, recent report of multiple dead deer on private land in Houston County, but those carcasses were decomposed and not suitable for testing when they were checked by the DNR.
Michelle Carstensen, a DNR wildlife health group leader, said EHD previously has hit hard in Wisconsin, North Dakota, South Dakota and Iowa. Some of the worst outbreaks were in 2012, she said, but Minnesota went unscathed. States further south, including Missouri and Florida, also are prone to EHD.
"It can cause massive numbers of deaths,'' Carstensen said. "It pops up locally, and it would be newsworthy if it finally landed here.''
Researchers say EHD can be worse in dry years because deer are more likely to congregate around water. It also can peak during humid periods late in the summer or early fall if whitetails are in abundance in those areas. Outbreaks remain active until rain disperses the deer, wind disburses the midges or frost kills them.
The virus causes mouth ulcerations, swelling of the head and neck and lung hemorrhaging. Most deer die within 36 hours of showing signs of the disease. The virus is not known to cause disease in humans.
Carstensen said EHD has killed hundreds of deer in Iowa this year. She was notified late last week by the Iowa Department of Natural Resources that EHD was the suspected cause in 589 deer deaths reported as of Aug. 29, with more reports streaming in. The mortalities were spread across 20 counties, mostly to the south.
Dale Garner of the Iowa DNR told Carstensen in an e-mail that the number of cases grew by 48% in the span of one week. The major area of activity has been in Warren County, squarely south of Des Moines.
In the Houston County deer farm case, the state Board of Animal Health said the two deer that died of EHD were part of a herd of 60 tame whitetails.
"The owner reports no additional mortality and is actively working to repel and reduce biting midges from their property,'' Board Assistant Director Linda Glaser said.
