The name alone sounds quite alarming — epizootic hemorrhagic disease. It’s an often lethal virus that has slammed the Michigan white-tailed deer herd in 2012, killing an estimated 10 times as many deer as it has in any other year.
“Historically, this has been a fairly isolated disease,” said Tom Cooley, a biologist and pathologist with the Wildlife Disease Lab at the Michigan Department of Natural Resources. “This year, it is much more widespread.”
Archery hunters, the first in the woods each deer season, and other visitors to Michigan’s outdoors have reported about 11,000 cases of whitetails that appear to have died from EHD, in 29 Michigan counties, as of late last week.
The most severe outbreak of EHD before this year was in 2010, when an estimated 1,000 animals died in just six counties.
EHD is transmitted by a midge, a gnat-like fly that is found throughout the world and usually in swarms around ponds, lakes, or other water sources.
In some locales, midges are known as sand gnats, sand flies, or no-see-ums. Once a deer is bitten by a midge carrying the EHD virus, the disease takes its course very quickly.
Within a week, the infected deer suffers a loss of appetite, it seems to abandon its fear of man, develops mouth ulcers and a high fever, and salivates excessively. The animal weakens rapidly as it experiences severe hemorrhaging.
“This is a fairly fast-acting virus,” Cooley said. “The deer is usually dead within two weeks.”
Whitetails claimed by EHD are often found dead near a source of water, likely the result of a futile attempt to find relief from the fever associated with the disease. EHD is not contagious within the deer herd, and it does not affect humans. There is no scientific evidence that humans can pick up the virus from midge bites, or by consuming venison.
Michigan’s Ionia County, located in the central part of the Lower Peninsula, between Grand Rapids and Flint, has been the hardest hit by the EHD outbreak, with more than 2,000 dead whitetails already reported. Cooley expects the number of fatalities there and elsewhere to continue to climb as more hunters are in the field in the coming weeks.
“We ask the public for help on this, to call our offices and give us the information on where the deer was found, if it was a buck, doe, or fawn, and any other details they can provide,” he said.
“We want to make an assessment on the impact of this disease that is as accurate as possible, but at this point, nobody really knows for sure. It’s going to be a very interesting fall as we find out what hunters are actually observing out there.”
Cooley said there is more than one strain of EHD, and unless the deer herd has been exposed to a specific strain, it has little built-up resistance or immunity to that virus.
“This year, we are likely dealing with a population of deer that have not been exposed to this disease, so no natural vaccination has taken place,” he said. “That’s likely why we are seeing higher mortality and morbidity rates.”
Hemorrhagic diseases, including EHD, are the most common maladies affecting deer in the United States, according to the University of Georgia’s Southeastern Cooperative Wildlife Disease Study. EHD was first identified in New Jersey in 1955, and it is a naturally occurring virus that appears to be worse in times of drought.
Cooley said the mild winter Michigan experienced, followed by a hot, dry summer, created near-ideal conditions for the disease-carrying midges.
Cooley said a couple hard frosts usually kill off the virus-carrying midges, but that some areas in Michigan have not yet experienced those needed cold snaps. He added that he would not expect to see another significant outbreak of this strain of EHD next year in the Michigan white-tailed deer herd, which is estimated to be about 1 million animals.
“Some of the deer will now have antibodies to protect them, and the does will pass on those natural antibodies to their fawns,” he said.
The majority of this year’s EHD cases in Michigan are found in the lower two-thirds of the Lower Peninsula. Cass, Branch, St. Joseph, Hillsdale, and Lenawee counties, which all border Ohio, have had multiple laboratory-confirmed cases of the disease.
Michigan wildlife biologists stressed they need the citizenry to continue to report cases of dead deer through the end of the year.
"Some people may have the perception that, once we have confirmed the presence of EHD in an area, we are no longer interested in additional reports of dead deer in those areas. That is not true. We want the reports," Wildlife Division Chief Russ Mason said. "Any and all reports, whether the deer seem to have died recently or not so recently, will help ensure we have accurate information about the extent of die-offs."
As of this past week, Ohio has had EHD deaths in its deer herd confirmed in 19 counties, but the numbers of whitetails lost to the disease are very low overall, according to Mike Tonkovich, wildlife research biologist with the Ohio Division of Wildlife.
“In the big picture, EHD hasn’t had a major impact on the deer herd regionally, but the situation might be different locally,” he said “Where the disease occurs, the mortality rates appear to be very high in that one specific area, but across the landscape, this has not been a big deal.”
Tonkovich said EHD has a “very spotty history” in Ohio, with the first confirmed cases occurring in 2002 in Meigs County. He said some deer deaths before that were likely because of EHD. “But we had no idea what it was at the time,” he said. “Conditions certainly point to some of those suspicious deer deaths in the 1980s being due to EHD.”
Tonkovich said that there might be a “lingering” impact from the disease in a few places, but that he believes the “worst is behind us.”
“I hope the frost has done its job, and we’ve seen the last of it for this year,” he said.
John Cooper from the Ontario Ministry of Natural Resources Fish and Wildlife Services in Peterborough said the province has seen no indication of EHD spreading from Michigan to the white-tailed deer population in the province.
Contact Blade outdoors editor Matt Markey at: email@example.com or 419-724-6068.