Waukesha County Dairy Cattle Test Positive for EHD

The Wisconsin Department of Agriculture, Trade and Consumer Protection said blood samples from a Waukesha County dairy herd tested positive for the virus that causes epizootic hemorrhagic disease, or EHD. State veterinarian Darlene Konkle said the affected animals were young heifers that had not yet given birth.

EHD is spread by biting midges, small flying insects related to mosquitoes. There is no treatment for the disease. Konkle said the cattle in the affected herd showed lesions on their hooves.

The disease has also been identified in tissue from wild and captive deer in the region. The Wisconsin Veterinary Diagnostic Laboratory, directed by Keith Poulsen, conducted blood testing as part of the investigation.

Poulsen said dairy farmers and trade associations had asked how much attention they should devote to the finding. “My answer is always the same: almost none,” he said in an interview at the World Dairy Expo in Madison. He said farmers were already managing issues including environmental conditions, weather and supply-chain and geopolitical concerns.

He also said many farms already use measures that can reduce insect exposure. These include insect-repellent ear tags, repellents applied to cattle and fans that improve air circulation inside barns.

Poulsen said the first strong frost would kill the midges, in the same way that frost kills mosquitoes. He nevertheless advised farmers to watch their herds for symptoms and contact veterinarians when needed. EHD can resemble other viral illnesses, he said, so animal-health officials collect samples to distinguish it from infections that could have greater economic consequences.