DETROIT — The number of deer killed by epizootic hemorrhagic disease in the last few weeks is insignificant when compared with the overall Michigan deer herd. But it might reduce deer numbers in part of the southwest Lower Peninsula and could become more common as the climate warms.
The disease was first identified in Michigan and New Jersey in 1955 and was seen here again in 1974. Then it disappeared until 2006, and the 2012 outbreak is the sixth in the past seven years.
It doesn’t infect people, but it has been responsible for killing 50 to 1,000 whitetails in localized areas nearly every summer since 2006, and this year’s toll so far is about 500.
There is no treatment for the disease, but the Department of Natural Resources wants landowners and hunters to help determine the extent of this often-fatal whitetail malady.
“We don’t have the people to respond to every report and go out and count all the dead deer,” said Dr. Steve Schmitt, the DNR’s head veterinarian. “We’re reaching out to concerned people and asking them to keep their eyes open and let us know about suspected cases of EHD.
“If they canoe a creek and see dead deer lying along the water, or they take a walk and see dead deer by a lake or pond, we’d like them to contact the nearest DNR field office.”
Epizootic hemorrhagic disease is a virus that can’t be transmitted directly from deer to deer. Instead, it is spread by biting Culicoides midges, also called no-see-ums, sandflies and gnats.
The disease infects whitetails, mule deer, pronghorn antelope and bighorn sheep. The obvious symptoms are a lack of fear of people and drooling, and the deer suffer from a fever and thirst, which causes them to go to lakeshores and riverbanks. About 25 percent of infected deer die from the disease, usually within two days of the appearance of outward signs.
The midges that spread epizootic hemorrhagic disease lay their eggs in muddy areas along the margins of streams, ponds and lakes, and the eggs overwinter there.
“The reason we see the outbreaks in warm years is that the hot weather dries up ponds and rivers and exposes more wet areas where the Culicoides midges can breed,” Schmitt said. “And milder winters mean that more eggs survive to hatch the next summer. More midges mean more deer get infected.”
Because Michigan is so rich in water, with 11,000 inland lakes and 30,000 miles of streams, the extremely hot weather such as this summer’s creates vast new areas of midge habitat.
Tim Licata lives in Grand Rapids and hunts a leased property in the northern end of Ionia County, where he and one of his hunting partners have found four deer that apparently died from epizootic hemorrhagic disease.
“All four were real thin and were lying right next to a pond on the property,” Licata said. “One of them was actually in the water. I guess when they’re near the end the fever gets so high they lie in the water trying to cool down.”
Licata said that the disease seems to be localized within the county.
“I’ve been talking to other hunters and some farmers, and it seems to kind of skip around. On one farm they found a dozen dead deer floating in a pond, but some guys who hunt about five miles away said they haven’t seen any sign of it,” he said.
Though the disease rarely kills more than 25 percent of the deer that are infected, “it can have a fairly spectacular rate in a localized area,” Schmitt said.
If a deer becomes infected and survives, it is largely immune for the rest of its life. It could be re-infected with a different strain of the virus, just as people can catch different strains of influenza, but the antibodies created during the initial bout of the epizootic hemorrhagic disease usually provide some protection against other strains.
One reason Michigan deer are so susceptible is that our state doesn’t see enough outbreaks for deer to develop widespread immunity.
In Alabama, deer in the warmer southern part of the state — where the infecting midges are more prevalent — are mostly immune to the epizootic hemorrhagic disease, whereas deer in northern Alabama still have regular outbreaks of the disease.
In south Texas and Florida, Schmitt said, whitetails have evolved alongside the virus for so long that they are born with immunity.
As of midweek, the DNR had confirmed 497 dead deer from the latest outbreak of epizootic hemorrhagic disease — 394 in Ionia County, 77 in Branch and the rest scattered among Calhoun, Cass, Clinton, Montcalm and St. Joseph counties.
The sight of a dozen dead deer floating in a lake can be upsetting, but those numbers really are insignificant in terms of the total whitetail population of about 1.5 million. Michigan drivers kill about 55,000 deer each year with cars. In Ionia County alone about 900 deer died in car crashes last year.
“There’s nothing we can do about [the disease],” Schmitt said. “If you see it break out in an area one year, you probably won’t see it there again for a long time, because the deer that survive have immunity.
“But it may surface the next year in a place 50 miles away. And if this hot weather continues, I would guess we’ll see more counties involved and larger numbers of deer.”
©2012 Detroit Free Press