Deadly disease confirmed in deer in 11 Michigan counties

The Michigan DNR says it has confirmed a deadly disease affecting deer in at least 11 counties in the state this year.

The DNR said that in 2024, deer in the following counties have tested positive for Epizootic hemorrhagic disease (EHD):

Barry, Berrien, Branch, Calhoun, Cass, Hillsdale, Kalamazoo, Kent, Ottawa, St. Joseph and Van Buren.

In 2023, the virus was only confirmed in Washtenaw County, but back in 2021, it was up to 24 counties.

EHD is an acute, infectious, often fatal viral disease of some wild ruminants. This malady, characterized by extensive hemorrhages, has been responsible for significant epizootics in deer in the northern United States and southern Canada.

A similar hemorrhagic disease called bluetongue also occurs throughout the U.S. and Canada. The two diseases are antigenically different.

Because of its very high mortality rate, EHD can have a significant effect upon the deer population in a given area, reducing numbers drastically.

The mode of transmission of EHD in nature is via a Culicoides biting fly or midge. Culicoides variipennis is the most commonly incriminated vector in North America. A deer must be bitten by a midge carrying the virus to become infected. The disease is not transmitted directly from one deer to another but must go through the insect vector. A common observation in outbreaks involving large numbers of deer is that they are single epizootics which do not recur. Die-offs involving small numbers of deer occur almost annually, and the disease appears to be enzootic in these areas. All documented outbreaks of EHD have occurred during late summer and early fall (August-October) and have ceased within two weeks of the onset of frost, which kills the midge.

Experimentally, the disease can be transmitted to susceptible deer by the inoculation of virus-laden material from infected deer by subcutaneous, intramuscular, intravenous or oral routes.

Hemorrhagic disease can be transmitted to other wild ruminants. The EHD virus can infect domestic animals, most commonly hoof stock, but rarely causes disease.

The edibility of the venison is not impacted by the disease. There is no evidence that humans can contract the EHD virus either from the midge or from handling and eating venison. Pets and wildlife cannot be infected by either midges or from EHD infected deer carcasses.

There is no known effective treatment or control of EHD.