ST. JOSEPH COUNTY, Mich. – A common viral deer disease with no known treatment is believed to have recently killed more than 100 deer in Michigan.
Over the past several weeks, the Michigan Department of Natural Resources has received reports of over 120 probable cases of epizootic hemorrhagic disease (EHD). The cases have primarily been reported from counties in the southwestern Lower Peninsula.
EHD is a viral, sometimes fatal, disease found in white-tailed deer, mule deer and elk. There is no known effective treatment for EHD in wild populations. The disease does not spread from deer to deer.
The DNR Wildlife Health Section and the Michigan State University Veterinary Diagnostic Laboratory recently confirmed EHD virus in a white-tailed deer from St. Joseph County, and lab results from deer from other counties are still awaiting confirmation.
“Although early reports indicate 2024 could see a significant outbreak of epizootic hemorrhagic disease in pockets of Michigan’s deer population, this isn’t necessarily unusual,” said Chad Stewart, acting supervisor of the DNR Wildlife Division’s Sustainable Populations Section.
According to Stewart, EHD-related deer deaths have been confirmed in Michigan since 2006. During an outbreak, anywhere between 50 to 1,000 deer died in isolated areas.
The largest die-off happened more than a decade ago. Officials estimate that in 2012, more than 14,000 deer in more than 30 counties died. There were no cases of EHD confirmed in 2014 or 2015, though cases have been confirmed annually since 2015.
The DNR expects to confirm more EHD cases in more counties in the coming weeks. Deer have to be tested within 24 hours of death to confirm EHD and the whole carcass is required.
Once EHD has been confirmed in a county, the DNR does not need to test any other deer from that county for EHD. Areas that reported cases in early August are expected to have the most cases and areas that didn’t see cases until mid- to late September will have a less severe impact.
What is epizootic hemorrhagic disease?
Epizootic hemorrhagic disease is a viral disease found in wild ruminants such as white-tailed deer, mule deer, and elk.
The disease is transmitted by a type of biting fly called a midge, and does not spread from deer to deer. It can be fatal, but deer that survive the virus become immune. There is no known effective treatment for EHD in wild populations.
“Deer that survive epizootic hemorrhagic disease develop immunity to the virus, and outbreaks are rarely seen in the same area in consecutive years,” Stewart said.
Studies have shown that a warm spring followed by a rainy July and hot, dry August appear to make an outbreak more likely. This is because the weather causes muddy areas where the fly lays its eggs and reproduces to become more common. Warm temperatures in late summer and early fall also help the virus replicate more rapidly, according to the DNR.
A hard frost will kill the insect, which should stop movement of the virus.
What should hunters know about EHD?
The DNR does not expect EHD to have a widespread impact on the deer population, but it could affect the population in localized areas. If an area sees significant deer die-off the numbers should rebound after two to three years.
While hunters should not eat venison from animals that are visibly sick, the DNR said that venison from a deer that had EHD is still safe to eat. There is no evidence humans can contract the virus from consuming venison. In fact, there is no evidence that humans or household pets can get the EHD virus, according to the DNR.
The DNR said that outbreaks of EHD are characterized in the following ways:
- Sick and dead deer are found in or around bodies of water.
- Illness in deer can come on suddenly and severely but also can linger for weeks or months in a low-grade state.
- In severe forms of the disease, deer lose their appetite and their fear of humans, grow progressively weaker, salivate excessively and finally become unconscious.
- Due to a high fever and dehydration, infected deer often seek water to lower their body temperature and to rehydrate.
Deer carcasses can be allowed to naturally decompose, the process does not spread EHD or contribute to outbreaks. Carcasses can be buried so that no body parts are showing, or they can be disposed of at landfills that accept household solid waste.
What to do if you suspect EHD
If you believe a deer has died from EHD, you should contact the DNR.
“If you suspect a deer death is due to epizootic hemorrhagic disease, please report it to the DNR so that we can track cases and better estimate the total number of deer affected in an area,” Stewart said. “Hunters’ observations can be especially helpful as they hit the field and look around this fall.”
Anyone who discovers sick or dead deer near bodies of water is urged to report it using the DNR’s Eyes in the Field webpage.