Updated

Updated · Wisconsin Department of Natural Resources (.gov) · Aug 18

Wisconsin DNR Confirms 2 EHD-Positive Deer in Washington County as Dead-Deer Reports Mount

Updated

Updated · Wisconsin Department of Natural Resources (.gov) · Aug 18

Wisconsin DNR Confirms 2 EHD-Positive Deer in Washington County as Dead-Deer Reports Mount

Q: What invisible environmental shift is causing this deadly deer virus to strike Wisconsin earlier and twice as hard this year?

The most likely driver is a weather shift that favored the virus-carrying biting midges: an earlier stretch of hot conditions, followed by patterns that create ideal muddy breeding habitat and concentrate deer at shrinking water sources. Wisconsin DNR has confirmed only the outbreak and its unusual timing, not a single official cause. But EHD is spread by Culicoides midges, and wildlife disease experts consistently tie severe outbreaks to warm late-summer weather, high insect activity, and drought-like conditions that push deer to gather around ponds, creeks, and mud edges where midges thrive. Reports from other recent Midwest outbreaks point to the same setup: warm, wet periods that boost midge numbers, then dry spells that leave exposed muddy margins and crowd deer together. That combination helps explain both why the outbreak started earlier and why it is roughly twice the usual size in Washington County. Wisconsin deer also have relatively low background exposure to EHD, so they lack the herd-level immunity seen in parts of the South, making outbreaks here deadlier when conditions line up. In short, the “invisible” shift is not the virus changing so much as the environment changing around it: warmer, longer midge season conditions and water-source stress that amplify transmission. High local deer density can make that worse by increasing contact between deer and infected insects.

3 articles · Updated · Wisconsin Department of Natural Resources (.gov) · Aug 18

Two wild deer found near Richfield and West Bend tested positive for epizootic hemorrhagic disease after Washington County residents reported a cluster of dead animals.
The Wisconsin DNR said many reports described healthy-looking deer dead in or near water, a common EHD sign because infected deer often seek water as fever sets in.
EHD is spread by midges and does not infect humans through handling deer, eating venison or midge bites; the agency urged residents to report sick or dead deer with location and carcass details.
Washington County had already seen an estimated 80 to 100 deer deaths since late July, but the DNR said such outbreaks are usually localized and fade after the first hard frost kills the insects.