Recent Washtenaw Deer Deaths Likely Caused by EHD, Not CWD

Photo: The water of the Looking Glass River reflects the blue sky, green shoreline grasses and a healthy white-tailed deer standing on the riverbank. This is one type of habitat where EHD outbreaks may occur. Courtesy of DNR

After finding a dead deer in her yard, a local resident reached out to The Sun Times News out of concern that the animal may have had chronic wasting disease (CWD). She reported hearing of similar deer deaths in the area, a worry shared by many who are more familiar with CWD than other deer illnesses.

But according to the Michigan Department of Natural Resources (DNR), the cause is most likely epizootic hemorrhagic disease (EHD), a separate illness that often appears during late summer and early fall.

Both EHD and CWD might look like “sick deer acting strange.”

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DNR Confirms EHD in Washtenaw County

The DNR recently reported Michigan’s first detected cases of epizootic hemorrhagic disease in 2025. The DNR Wildlife Health Section, Michigan State University Veterinary Diagnostic Laboratory and the Southeastern Cooperative Wildlife Disease Study confirmed the EHD virus in free-ranging white-tailed deer from Eaton, Jackson, Van Buren and Washtenaw counties.

EHD is a viral, sometimes fatal disease that periodically affects white-tailed deer in Michigan. It is spread through the bite of an infected midge, or biting fly. Unlike CWD, deer cannot transmit EHD directly to one another. The virus must pass through an insect bite.

“In past years when we’ve confirmed EHD, it has typically affected only one or a few counties,” said Brent Rudolph, deer, elk, and moose management specialist for the DNR Wildlife Division. “Occasionally, localized outbreaks have been detected in a dozen or more counties, including as many as thirty in 2012.”

EHD typically appears in late summer and early fall. Outbreaks can be worse after a wet spring followed by a hot, dry summer, but the first frost kills the midges and stops the disease from spreading. Despite alarming local die-offs, statewide populations usually recover.

“Deer that survive epizootic hemorrhagic disease develop immunity to the virus, and outbreaks are rarely seen in the same area in consecutive years,” Rudolph said.

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Key Differences Between EHD and CWD

Feature	EHD	CWD
Cause	Virus spread by biting midges	Prion (misfolded protein) spread through fluids and environment
Timeline	Sudden onset; deer may die in 1–3 days	Slow progression over months or years
Appearance	Often healthy-looking until death	Thin, weak, drooling, unsteady
Season	Late summer–early fall	Any season
Transmission	Not contagious deer-to-deer	Contagious; persists in environment
Recovery	Some deer survive, gain immunity	Always fatal
Control	Ends with frost	Ongoing management challenge

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Report Sick or Dead Deer

The DNR notes that sick or dead deer are often found near water. EHD causes high fever and dehydration, leading deer to seek ponds, streams, or even backyard birdbaths to cool off.

Visible symptoms of EHD can include lethargy, disorientation, swelling around the eyes or head, a bluish tongue, and bloody discharge from the nose or mouth. However, these signs can overlap with other deer illnesses or injuries. EHD can only be confirmed through testing by a qualified laboratory.

Once EHD is confirmed in a county, further testing isn’t required, but ongoing public reports help the DNR track the spread and scale of the outbreak.

If you suspect a deer has died from EHD, report it through the DNR’s Eyes in the Field system at Michigan.gov/EyesInTheField.

How to Tell EHD and CWD Apart

EHD (Epizootic Hemorrhagic Disease)

• Caused by a virus spread through biting midges.
• Occurs in late summer and early fall.
• Sudden deaths, often near water.
• Deer may look healthy until they die.
• Signs: drooling, swelling around eyes or head, bluish tongue, bloody nose or mouth.
• Not contagious between deer.
• No risk to humans or pets.

CWD (Chronic Wasting Disease)

• Caused by a prion (abnormal protein).
• Can occur any time of year.
• Slow, progressive illness over months or years.
• Deer appear thin, weak, drooling, unsteady.
• Often wander aimlessly or lose fear of people.
• Contagious among deer and persists in environment.
• Always fatal.