Wisconsin Deer Enduring Record EHD Deaths in 3 Southeastern Counties

   Deer in southeastern Wisconsin are suffering the state’s worst outbreak of epizootic hemorrhagic disease since this viral disease first appeared in 2002, with nearly 900 whitetails likely dead as of early September.

   Confirmed reports of EHD-killed whitetails as of Sept. 4 put the count at over 700 in Washington County, over 150 in Waukesha and over 30 in Ozaukee counties.

   Disease specialists at the Department of Natural Resources list only firsthand reports of dead deer in the agency’s totals. Erin Larson, the DNR’s deer-herd health specialist, said the agency also reviews all EHD reports to remove any that were based merely on bad odors, second-hand reports or duplicate reports in which two or more people found the same dead deer.

   Whitetails stricken by this virus often die in clusters near ponds, creeks or other water sources where they drank to battle thirst, dehydration and high fevers caused by the virus. Deer typically die within a week of being bitten by the small fly, or “midge,” that carries EHD. Most EHD reports involve dead deer, but can include deer that appear dazed or lethargic, with their tongues hanging out, and foam or pink froth around the mouth. EHD victims die so quickly they lose little weight and their bodies look normal.

   Almost all EHD cases in Wisconsin occur in August and September, but this year’s outbreak began in late July, the earliest such deaths on record. Previous outbreaks didn’t start until late August or early September. EHD outbreaks wane in mid-September as temperatures drop, and end when early frosts kill biting insects. The state’s latest EHD case on file is Oct. 8.

   Some infected deer do not die, which hunters might notice if a deer they shoot has cracked, broken or elongated hoofs, common symptoms of EHD survivors.

Although the deer in this DNR photo are healthy, whitetails stricken with EHD (epizootic hemorrhagic disease) typically seek out ponds, creeks, shorelines and other water sources to relieve severe hydration and fatally high body temperatures caused by the disease. — Snapshot Wisconsin photo

   In contrast, no deer survives chronic wasting disease, which has been found in wild deer in 51 of Wisconsin’s 72 counties. CWD-killed deer typically die alone, and are found year-round, their bodies emaciating into skin and bones during the final four to six weeks of CWD’s prolonged illness.

   Hunters should remember those differences when reading social-media claims that EHD threatens deer more than CWD. EHD does not kill deer in late fall, winter, spring or early summer; and photos of emaciated deer are likely dying of CWD, not EHD.

   Further, even though EHD can decimate whitetails on individual properties and possibly townships (36 square miles) deer herds typically rebound quickly. Since EHD’s first appearance in Wisconsin nearly 25 years ago, it has never struck the same area two years in a row. Therefore, deer herds quickly replace EHD losses in subsequent breeding cycles.

   That disease pattern, however, also prevents Wisconsin deer from building EHD antibodies that protect deer in Southern states, which suffer few losses during annual outbreaks. Deer in Oklahoma, for instance, often get infected by EHD but seldom die from it. Mark Ruder, director of the Southeastern Cooperative Wildlife Disease Study group at the University of Georgia, reports that half to 90% of Oklahoma’s whitetails carry antibodies against EHD and blue tongue, a related disease.

   “Oklahoma deer pretty much get infected regularly; they just don’t care about it,” Ruder told the National Deer Association.

   But much like other states in the upper Midwest and mid-Atlantic states — including Michigan, Minnesota, Illinois, Indiana, Ohio and Pennsylvania — Wisconsin is on the northern fringe of EHD’s range. Because EHD doesn’t strike these states repeatedly, deer that survive an outbreak and build antibodies seldom live long enough to make their offspring immune.

   Therefore, deer in these states often suffer heavy losses when EHD strikes, which happened in 2025 when Ohio reported nearly 9,300 sick or dead deer. The Ohio DNR reported that 65% of those deaths (nearly 6,000 deer) came from just four counties along the Ohio River: Athens, Meigs, Morgan and Washington. Follow-up tests of hunter-killed deer in those counties found 54% carried EHD antibodies, showing they had been infected but survived.

   Larson encourages citizens to report any sick or dead deer they find to the Wisconsin DNR through this link: Sick or Dead Wildlife Reporting Form. You can also file reports by phone, (608) 267-0866 or email, DNRWildlifeSwitchboard@wisconsin.gov. Include the number of deer, if they were sick or dead, their location and county, and your contact information.

   Larson said no one can predict when or where EHD will strike. Neither can anyone prevent outbreaks, even though some water-treatment products claim to block the disease by removing nutrients that feed biting insects. To be effective, you’d have to find and treat every puddle or seep in the area. Still, mild winters followed by hot, dry summers often trigger bursts of the midges (no-see-ums) that spread EHD.

   Wisconsin’s EHD history is erratic. That first case in September 2002 involved 14 dead deer in a small area in Iowa County. Ten years passed before EHD struck again in Fall 2012, killing over 370 deer across 12 southcentral counties from late August to early October. Dane County reported 131 dead deer, followed by Columbia, 102; Waukesha, 49; Jefferson, 47; and Marquette, 12.

   The 2012 outbreak was perhaps the United States’ worst EHD season, killing nearly 3,000 deer in Iowa, and over 14,000 deer across 30 counties in Michigan. “In 2012, you could walk from South Dakota to Indiana in a death zone the whole time; a thousand miles of contiguous outbreak area,” Ruder told the NDA.

   Wisconsin’s next outbreak wasn’t until 2019, when the DNR recorded over 307 dead deer in seven counties, with the most in Crawford, 218; Vernon, 41; Grant, 20; and Sauk. 15.

   Subsequent outbreaks were smaller, with 77 dead deer in 2020 — 43 in Buffalo and 34 in Oconto counties; and less than 40 deaths in 2021, with less than 20 each in Juneau and La Crosse counties. Likewise, only four counties reported EHD-killed deer in 2024, with Jackson, Chippewa, Monroe and Waukesha counties ranging from three to 30 dead deer.

   Few of Wisconsin’s 1,700 EHD deaths since September 2002 were certified in a lab. EHD tissues degrade so quickly it’s difficult to get viable samples. Even so, EHD conditions and symptoms are so distinct that biologists diagnose these deaths with confidence.

   In contrast, the DNR documented 2,040 CWD cases in 2025 alone, and 16,407 cases since the disease’s initial discovery in February 2002, though less than 30% of Wisconsin deer hunters have submitted a sample for CWD testing.