Deer Deaths in Houston and Winona Counties Caused by Midge-Borne Virus

The Minnesota Department of Natural Resources has confirmed two cases of epizootic hemorrhagic disease (EHD) in wild white-tailed deer in Minnesota. EHD is a viral disease of deer and some livestock that is spread by a biting insect called a midge.

“All of our neighboring states have been dealing with EHD for years,” said Michelle Carstensen, DNR wildlife health program supervisor. “Fall 2019 was the first time we had detected this virus in wild deer in our state, with deaths reported in Stearns and Houston counties. So it was not surprising that it showed up again, particularly with low water conditions.”

The DNR received reports of deer deaths throughout September in both Houston and Winona counties, amounting to over 20 animals. Tests from two of the deer in Houston County were positive for EHD; other deer were too decomposed to test. DNR has notified the Board of Animal Health (BAH), and BAH has also received all testing results. Reported cases in Minnesota are limited two counties thus far; however, Wisconsin has recently confirmed several EHD cases in nearby La Crosse County.

The disease incubates for five to 10 days, and most infected deer die within 36 hours of exhibiting symptoms.

“EHD is both naturally occurring and seasonal,” Carstensen said. “We expect the potential for infection to end soon because freezing temperatures kill both the virus and midge that carries it.”

Drought conditions have likely increased risk for this virus, as midges are limited to fewer water sources to breed and this can promote virus propagation. Wisconsin, Nebraska, Iowa, Illinois, Michigan and Ohio report EHD mortalities in wild deer almost every year. In some cases, the disease can dramatically reduce a local deer population in the short-term but has a relatively small impact on the overall deer population. There are no management interventions available to combat the disease.

Finding multiple dead deer near a water source is typical of an EHD die-off. Fever drives the animals to seek water, but they die from internal lesions and hemorrhages.

People who find a dead deer should report it to the nearest DNR area wildlife office. Contact information for each office is listed on the DNR Website. EHD is not a threat to humans or animals outside the deer family. Even so, people should not consume deer that appear to be sick or deer that appear to be in poor health.