What You Need to Know About Deer Diseases in Michigan
Steve Griffin 09.20.12
What do you, a deer hunter, need to know about Michigan’s three deer-related diseases epizootic hemorrhagic disease (EHD), bovine tuberculosis (bovine TB), and chronic wasting disease (CWD)?
- That the first (EHD) can whallop deer numbers in fairly small areas, often less than a township, where hunters will have to wait patiently a few years for the local herd to rebound;
- That the second (bovine TB), probably northeast Lower Michigan’s for keeps, doesn’t render deer meat inedible and can be held in check with hunter help;
- That regarding the third (CWD), “We dodged the bullet,” DNR veterinarian Dr. Steve Schmitt says, in that it was found in only one privately owned deer a few years ago; Michigan hunters who travel out of state can help keep it that way.
EHD is getting plenty of press this year, with reports from 24 counties of whitetails dying after becoming infected with a virus carried by a biting fly. Some deer shrug off the virus; others, though, bleed internally, quit eating, become docile, weaken, drool, and pass out and die, often near water to which fever drives them.
That brings things full circle: the insects that carry the virus spend larval stages in mud and hatch when the weather gets hot. Most of the adult flies die during a normal Michigan winter, or at least what we used to call normal.
Last year’s mildest-ever winter set the stage for adults to join a bumper crop of just-hatched midges, and the effects are told in the death toll – 4,300 reported by mid-September and certainly many more undetected or unreported. Hardest hit is southern Lower Michigan.
A good hard frost should kill the flies and bring this year’s outbreak to a close. And deer that were bitten and survived should have some immunity.
But that will be cold comfort to hunters whose favorite stand will have up to 40 percent fewer deer pass it.
Deer carry the virus for less than a month, the vet said, and only living deer, not dead ones, are a source of virus for the midge flies.
People aren’t in the disease loop at all; they can’t contract EHD from insects or venison, Schmitt said.
Schmitt said EHD and the look-alike blue-tongue disease have long been known, but outbreaks in Michigan had only been documented in 1955 and 1974, until its five-of-six-year run since 2007. It’s been found in 34 Michigan counties since 1955, but 26 of them have had only a single-year outbreak.
Wide awareness of EHD likely boosts reports, but “I have no doubt that climate change is involved,” Schmitt said. Warm winters and hot summers both favor midge reproduction.
The other maladies?
There’s no CWD known in Michigan, and Schmitt said hunters can help keep it that way by abiding by laws that allow only boned meat to be brought into the state from hunts in states or provinces known to have CWD.
And in the northeastern Lower Peninsula, where bovine TB incidence has been cut from 5 percent to less than 2 percent through reduction of the herd and prohibition of baiting and feeding? He said hunters can help manage the herd by complying with the no-bait rule still in place there, and by taking a doe when given the opportunity.
Careful field dressing, and cooking venison until the juices run clear, dodge potential bovine TB transmission to people. Schmitt said the only known case is a hunter who both cut into a TB lesion and then cut himself.
