Outbreaks of the deadly virus epizootic hemorrhagic disease continue to worsen in deer herds across much of the Midwest.
The virus appears to be spreading in Indiana and Illinois. The discovery of a trophy-sized buck – apparently killed by EHD -- in southern Illinois’ Perry County has drawn much attention, but wildlife officials are more concerned by outbreaks in northern areas of the state not normally affected by the disease.
“We’ve never seen it here,” Chris Anchor, wildlife biologist for Cook County in northern Illinois, told the Chicago Tribune. “This is a disease that usually does not get this far north in the state.”
While the southern portions of Illinois generally have many more reported cases of EHD each year, easily the most reports this year have been in Cook County, which includes the Chicago area. Since August, there have been more than 250 reports of EHD-related deer deaths in Cook County, tops in the state. The second-most were in Macon County (69) in the central part of the state.
“We’re trying to remove dead deer that are in picnic areas, near trials, parking lots, and any animals that died in the water,” Anchor said. “All we can do is sit back and let the disease run its course.”
As of the first week in September, there have been more than 700 reports of dead deer in 51 Illinois counties.
In Indiana, the toll has reached 40 counties in which EHD has been reported or suspected in deer. After tissue samples were taken from dead deer and results returned from laboratory tests, EHD was confirmed in four counties. Also, the Indiana Board of Animal Health identified EHD at captive facilities in four more counties and in cattle at another.
From results of samples sent to the Southeastern Cooperative Wildlife Disease Study at the University of Georgia and Purdue University, two strains of the disease were confirmed: EHD V-2 and EHD V-6.
“Basically, 10 years ago we didn’t have the EHD V-6 strain in Indiana,” said Chad Stewart, deer management biologist for the Indiana Department of Natural Resources. “It’s just recently been documented, so it’s still relatively new on the landscape. It may be an explanation for some of these harder hit pockets.”
The Indiana outbreak is bordering on the one from five years ago when EHD was reported in 59 counties in the state and confirmed by lab tests in 17.
“If it’s not as bad this year as it was in 2007, it’s getting close,” Stewart said. “We did a lot more testing and confirming in 2007. This year we’re lying back because the tests are so expensive and we know what it is.”
EHD outbreaks tend to be more significant in dry conditions, and much of the Midwest suffered prolonged drought this summer. A lack of rainfall drives deer to congregate near fewer remaining water sources, where they can be bitten by a midge, the small flying insect that transmits the illness.
Deer infected with EHD may appear depressed or feverish and act erratically. Other signs may include blue-tinted tongue or eyes, ulcers on the tongue, sloughed hooves, high fever and swelling of the head, neck, tongue or eyelids.
In Ohio, where archery season just opened, deer project coordinator Mike Tonkovich of the Division of Wildlife warned hunters about infected deer.
“They may very well see some strange behavior,” he told the Columbus Dispatch. “We’re seeing deer behave abnormally before they die.”
One such incident involved a squirrel hunter who tried to shoo away an oddly behaving deer and eventually shot it with his .22 as the deer continued to menacingly approach.
EHD is believed to have been around for more than a century, but this year’s outbreak could the worst since 2007, according to Kip Adams, wildlife biologist for the Quality Deer Management Association.
“It’s setting the stage to be a really terrible year,” Adams said. “It used to be talked about more as a southern disease. But in the last several years, it’s amazing how the northern states have had far worse outbreaks than ever before.”
Aside from an insect-killing frost, there is no known effective treatment for EHD. It is often fatal to deer, although some typically survive the virus. Mortality rates vary for outbreaks, ranging from minimal to 50 percent, but severe outbreaks rarely occur in subsequent years due to immunity gathered from previous infections.
The disease can also be selective, causing severe losses in one area and not affecting others nearby.
“Typically, outbreaks tend to be localized with a very patchy distribution across the landscape,” said Tom Micetich, deer project manager for the Illinois Department of Natural Resources. “This occurs because environmental and habitat conditions play an important role in producing just the right mix of virus, high gnat populations and susceptible deer.
“While deer may be dying on your property, your neighbor may not find any.”
EHD has also been confirmed or suspected this year in Iowa, Michigan, Missouri, New Jersey, North Carolina, Kentucky, Ohio, Pennsylvania, South Dakota and Wisconsin.