EHD Outbreak Kills Over 2,300 Deer in Wisconsin
The state is experiencing its largest documented occurrence of epizootic hemorrhagic disease in history.
Updated on Oct. 20, 2026 in Severe Weather
Live Poll
Should the DNR restrict hunting permits when local deer populations suffer major disease outbreaks?
An epizootic hemorrhagic disease (EHD) outbreak has killed at least 2,305 deer across eight Wisconsin counties. This event marks the largest documented instance of the virus in the state since it was first recorded in 2002.
Why it matters
The viral disease is transmitted by biting midges, which see increased populations during the warm conditions of late summer and early fall. The spread of the virus poses a significant challenge for wildlife management and local agricultural livestock, which can also be affected.
Washington and Waukesha counties suffered the highest losses with 1,300 and 600 deaths, respectively. Confirmed cases were also found in two dairy heifers in Waukesha County and captive deer on farms in Washington County.
The players
Department of Natural Resources
This state agency is responsible for managing Wisconsin's natural resources and is currently tracking the EHD outbreak through public reports and sampling.
The details
The Department of Natural Resources tracks this disease through public reporting and the sampling of deceased deer. Midges spread the virus to wild deer populations as well as some captive animals and livestock.
Timeline
2002: EHD first documented in Wisconsin.
2012: The previous record for the largest EHD outbreak occurred.
July 23, 2026: Testing was completed for captive deer in Richfield.
August 20, 2026: Testing was completed for captive deer in Colgate.
October 16-17, 2026: Cold air and frost potentially ended the outbreak.
Seasonal Patterns
The current outbreak represents a significant escalation in scale compared to the 2012 EHD outbreak, which was previously the largest event on record. The surge follows the typical pattern of viral spread during warmer late-summer months.
Residents should continue to report dead or sick animals to state authorities to assist in ongoing surveillance efforts. You can submit information regarding sightings of afflicted wildlife through the official DNR dead or sick wildlife form.
The takeaway
The arrival of frost in mid-October likely halted the transmission cycle of the virus by reducing midge populations. Landowners and farmers in affected regions should monitor their livestock and herds for symptoms until the risk fully subsides.
Further reading
Learn more about local wildlife monitoring in Wisconsin Severe Weather.
More information
To report sightings or view official guidelines, visit the DNR dead or sick wildlife form.
Source note: This article includes information reported by Journal Sentinel.
Live Poll
Should the DNR restrict hunting permits when local deer populations suffer major disease outbreaks?
