Epizootic hemorrhagic disease expands in the US as 2026 outbreaks hit wild deer

A new Nebraska study shows that epizootic hemorrhagic disease virus (EHDV) was already circulating widely in wild cervids before the current 2026 outbreak season. Testing of hunter-harvested deer during the 2025 season found EHDV in nearly 12% of samples, alongside frequent bluetongue virus and chronic wasting disease detections. In 2026, the field picture has become much more visible: Wisconsin is experiencing its largest recorded EHD outbreak, while confirmed or suspected activity has also been reported in Michigan, New York, West Virginia, Missouri and other states.

The Nebraska study tested 780 retropharyngeal lymph node samples collected from wild cervids during the 2025 hunting season. The same samples were screened for chronic wasting disease (CWD), bluetongue virus (BTV) and EHDV, providing an unusual integrated picture of three major cervid diseases.

EHDV detected in almost 12% of Nebraska deer

Overall, 93 of 780 animals, or 11.9%, tested positive for EHDV. BTV was detected even more frequently, in 17.9%, while 25% were positive for CWD. Almost one in ten animals carried evidence of at least two of the three pathogens, and 11 deer tested positive for all three. The distribution was not uniform. EHDV detections were more common in white-tailed deer than mule deer, and spatial analysis identified clusters in southern Nebraska, particularly around Adams and Harlan counties.

The study is important because it used tissue already collected for CWD surveillance. The authors show that the same retropharyngeal lymph nodes can support simultaneous monitoring of prion disease and vector-borne orbiviruses, potentially expanding EHDV and BTV surveillance without creating a completely separate sampling system.

Wisconsin: more than 1,700 suspected deer deaths

The 2026 season has produced a much more dramatic signal in Wisconsin. As of 28 September, EHD had been confirmed in wild deer in Washington and Waukesha counties, with suspected cases also reported in Dodge, Fond du Lac, Jefferson, Milwaukee and Ozaukee counties. Wisconsin DNR estimates included just over 1,200 affected deer in Washington County and more than 400 in Waukesha County, with approximately 90 reports in Ozaukee and around 80 in Dodge. Altogether, reported mortality associated with the outbreak is well above 1,700 deer. Wisconsin officials describe it as the state's largest EHD outbreak recorded to date.

The outbreak has also crossed the wildlife–livestock interface. In September, dairy cattle in Waukesha County tested positive for EHDV. Clinical disease in cattle is usually absent or mild, but the detections confirm that infected Culicoides midges are transmitting virus beyond wild cervids.

Michigan, New York and West Virginia also report activity

Michigan confirmed its first 2026 EHD cases in September in free-ranging white-tailed deer from Branch, Ingham, Jackson and Lenawee counties. State officials said the level of activity was broadly similar to 2025 at the time of the announcement.

In New York, an EHD outbreak was confirmed in Suffolk County, after approximately 20 dead deer were reported near the Southampton marshes. In the same region, a deer from Riverhead tested positive for bluetongue virus rather than EHDV, illustrating that the two Culicoides-borne orbiviruses may circulate simultaneously and cannot reliably be distinguished from clinical signs alone.

West Virginia had confirmed hemorrhagic disease in five counties by 21 September, with 140 dead deer reported, including 108 in Mingo County.

Missouri has also received reports of hemorrhagic disease during the 2026 summer and early autumn and has asked the public to report sick or dead deer to help determine the geographical extent of transmission.

Not every state is seeing a severe season

The 2026 picture is highly regional. Indiana, for example, reported only a low level of suspected EHD activity by mid-September, with cases scattered across the state and no need for new reductions in antlerless deer harvest limits.

Weather strongly influences that pattern. Hot, dry late-summer conditions can favour the muddy, shallow-water habitats used by Culicoides midges, while infected deer frequently congregate near water because fever and dehydration drive them to drink. Transmission normally ends after the first hard frost kills the vector population.