White-Tailed Deer Outbreak: Understanding Epizootic Hemorrhagic Disease in Wisconsin
A significant number of white-tailed deer have been reported dead in Wisconsin due to an outbreak of epizootic hemorrhagic disease (EHD) believed to be transmitted by tiny biting insects. The outbreak, which started in July in Washington County, has now spread to Waukesha and Ozaukee counties, with over 700 reports in Washington County, more than 150 in Waukesha County, and just over 30 in Ozaukee County.
EHD is a viral disease that affects white-tailed deer and other hoofed animals, transmitted by biting midges. Infected deer may exhibit symptoms such as high fever, internal bleeding, organ damage, weakness, excessive salivation, and foam around their noses. Sick deer often seek water sources due to fever and dehydration, leading to many dead deer being found near ponds.
The Wisconsin Department of Natural Resources (DNR) confirmed EHD in two deer from Washington County and continues to monitor reports of dead deer in the affected counties. EHD is less common in Wisconsin compared to Southern and Western states, with sporadic outbreaks occurring since 2002, including one in 2012 across eight counties.
The DNR notes that death rates can be higher in areas where hemorrhagic disease is rare, especially in deer herds with high population densities. Warmer temperatures may allow the insects that spread the disease to expand farther north, potentially leading to more outbreaks. Survivors of EHD can develop antibodies that may provide some protection in future outbreaks, and the disease typically subsides after the first hard frost.
It is important to distinguish EHD from chronic wasting disease (CWD), as they are caused by different agents and progress differently. EHD is caused by a virus transmitted by biting insects, while CWD is caused by abnormal proteins and spreads through infected animals and environments. The viruses that cause hemorrhagic disease do not infect humans, so there is no risk to people from handling infected deer, consuming venison from infected deer, or being bitten by midges carrying the virus.
The Wisconsin DNR urges residents to report any unusual numbers of sick or dead deer to aid in monitoring the outbreak and emphasizes that the viruses causing hemorrhagic disease do not pose a threat to human health.