Wisconsin EHD Deer Outbreak Expands to Six Counties

Key points

• EHD outbreak now confirmed in six Wisconsin counties.
• Over 700 dead deer reported in Washington and Waukesha counties.
• Disease spread by midges; no human risk.
• Outbreaks typically end after first frost.

Background

In early September 2026, Wisconsin faced a significant EHD outbreak, with over 700 dead white-tailed deer reported in Washington and Waukesha counties. The Department of Natural Resources (DNR) confirmed the virus in Washington County and noted suspected cases in Ozaukee and northern Waukesha counties. EHD, a recurring issue since 2002, is spread by biting midges and typically fades after the first hard frost. While the disease does not affect humans, it causes rapid illness and death in deer, with survivors developing antibodies.

Why it matters

The expansion of the EHD outbreak to six counties highlights the ongoing threat to Wisconsin's white-tailed deer populations. Although the disease does not pose a risk to humans, it has significant ecological and economic impacts, affecting wildlife management and local communities. Understanding the spread and lifecycle of EHD is crucial for predicting future outbreaks and implementing mitigation strategies.

What to watch

The DNR continues to monitor deer deaths and urges the public to report sick or dead deer. Outbreaks typically end after the first hard frost, which may slow transmission as midges die. Further testing and monitoring will be conducted to track the spread of EHD across the state.