Viral, fly-borne disease found in Midwest deer

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MILWAUKEE — A disease is killing hundreds of deer in the Midwest this summer. And it’s not chronic wasting disease.

Officials in Michigan confirmed in early August that Epizootic Hemorrhagic Disease, or EHD, killed deer in two counties in the south central part of the state.

Deer deaths have also been reported in 11 counties in Indiana; officials there suspect the cause is EHD but are awaiting confirmation from laboratory tests.

EHD is a viral disease transmitted by a midge, or biting fly.

Found in wild ruminants such as deer and elk, the disease causes extensive internal bleeding. Infected deer are attracted to water to combat the fever and dehydration due to the hemorrhaging.

The disease is characterized by sudden onset, according to wildlife health sources. Deer lose their appetite and fear of humans, grow progressively weaker, salivate excessively and finally become unconscious.

Infected deer often are found sick or dead along or in bodies of water. There is no evidence that humans can contract the EHD virus.

Michigan has observed EHD outbreaks each year since 2006. Before 2006, EHD was seen in Michigan in 1955 and ‘74.

The estimated mortality has varied from 50 to 1,000 deer per year in the affected areas, according to Michigan officials.

“Due to the prolonged, dry, hot weather this year, we are not surprised to see EHD emerge again,” said Tom Cooley, DNR wildlife biologist and pathologist. “Mortality numbers will depend on how widespread the disease is. Die-offs usually occur within one watershed area. If multiple watersheds are involved, the total mortality is higher.”

There is no known effective treatment for, or control of, EHD.

The disease has been seen for decades in most areas of the United States, especially the southeast states and Texas. It has been less commonly observed in Great Lakes and New England states, although that may be changing.

In 2002, EHD was confirmed in Iowa County, Wis. Fourteen deer were found dead in one area, said Tom Hauge, Department of Natural Resources director of wildlife, and subsequent testing was positive for EHD.

“That’s the only deer mortality we’ve recorded in Wisconsin from EHD,” Hauge said. “It’s something we’re routinely looking for, though.”

Hauge said EHD is one of the standard tests conducted when blood samples are taken from live deer and elk in Wisconsin.

As an example, blood taken from animals in the northern and eastern study areas of Wisconsin’s deer research projects has shown no evidence of EHD.

Where EHD is more common, deer have built up antibodies to the disease.

Deer in the Upper Midwest do not have the benefit of these antibodies. Mortality from EHD may be severe but is typically restricted to localized areas, according to Michigan officials.

Hauge said, as always, the DNR requests the public to contact the department with observations of sick or dead deer.

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