Midge-borne virus detected in Wisconsin dairy herds as deer outbreak intensifies
Epizootic hemorrhagic disease, a midge-transmitted virus that has infected over 1,600 deer across southeastern Wisconsin, has now been confirmed in dairy cattle in Waukesha County. The disease, which does not affect humans and typically causes mild symptoms in cattle, poses no food safety risk to consumers. Officials note the virus circulation indicates environmental exposure but remains uncommon in domestic livestock.
Epizootic hemorrhagic disease emerges when biting midges transmit the virus during late summer and early fall months. Wisconsin sits at the northern boundary of where these insects typically thrive, explaining why the state experiences only infrequent outbreaks. The current situation marks the second documented occurrence of EHD in Wisconsin cattle since 2013, though the wild deer population bears the far greater burden, with over 1,600 suspected infections concentrated in two counties.
The virus presents differently across species: while it can be lethal to deer, cattle usually show no symptoms or mild signs including lameness and sores. Currently, no treatment exists for the disease. Cold weather provides natural relief, as the first hard freeze kills the midge populations responsible for transmission, typically ending seasonal outbreaks.
The detection poses minimal direct risk to consumers and livestock producers, as the virus does not threaten human health and infections in cattle remain uncommon. However, the outbreak may concern dairy operations regarding animal welfare and herd management practices. Wildlife populations face greater vulnerability, potentially affecting deer populations and ecosystem dynamics in affected regions. Producers may incur costs monitoring herds and implementing parasite control measures to reduce exposure risk.