Wisconsin's largest EHD outbreak tallied at at least 2,305 deer in eight counties

An outbreak of epizootic hemorrhagic disease, known as EHD, has affected at least 2,305 white-tailed deer in at least eight southeastern Wisconsin counties this year, according to the Department of Natural Resources.

The DNR says this is already the largest EHD outbreak in state history. As of Oct. 12, the estimated toll was just over 1,300 deer in Washington County and just over 600 in Waukesha County, followed by about 150 in Dodge County, about 140 in Ozaukee County, about 50 in Jefferson County, about 35 in Milwaukee County, about 20 in Sheboygan County and fewer than 10 in Fond du Lac County. The figures count only deer reported to the DNR, so the actual toll is likely higher.

EHD is a viral disease spread by midges, a small biting fly. It affects deer and other hooved animals but does not infect humans. Cases are usually seen in late summer and early fall and generally subside after the first frost or freeze kills the insects.

The disease can kill quickly, causing internal bleeding, high fever and organ damage, and sick deer often seek water to cool down. Some deer do survive. EHD was first documented in Wisconsin in 2002.

This year's outbreak became apparent in late July and early August after reports of dead deer in Washington County, and the DNR announced on Aug. 17 that it had been detected in deer sampled in Richfield and West Bend. It has also been confirmed in dairy heifers at a farm in Waukesha County and in captive deer at two deer farms in Washington County.

Dead deer were recently reported near Tichigan in Racine County and near Whitewater in Walworth County, which could expand the outbreak area. Samples from deer in Racine, Walworth and Marinette counties so far came back as EHD undetected. The DNR says local herds have recovered quickly after past outbreaks, it does not plan to reduce antlerless tag availability because of this outbreak, and it is asking the public to report dead or sick wildlife through its wildlife health webpage. Frost and freeze conditions on Oct. 16 and 17 may have killed the midges and ended this year's outbreak.