Photo by Cindie Hansen, Unsplash

August 1, 2023

EHD in Illinois – Summer 2023

Each year between August and October, especially during hot and dry summers, landowners, deer hunters and wildlife enthusiasts are encouraged to keep an eye open for signs of an outbreak of Epizootic Hemorrhagic Disease (EHD) in the local white-tailed deer herd.

A chart of Illinois EHD Suspected Cases from 2005-2023 listing the year, number of reports, number of deer, and the number of counties.
Table1. Numbers of suspected Epizootic Hemorrhagic Disease (EHD) cases in Illinois from 2005 to 2023. Table courtesy of the Illinois Department of Natural Resources.

The Illinois Department of Natural Resources (IDNR) continually monitors the status of this disease with the assistance of the many individuals who report dead deer observed in the field. Although there has not been a published report on EHD for the OutdoorIllinois Journal since 2020, IDNR has continued to compile data. The information has been included in the following table and map to provide a full picture of EHD trends.

In 2022, EHD activity was higher than previous years with the highest number of reports coming from Cumberland, Macon and Peoria counties. A limited number of reports also came from east central Illinois across the state to the west and stretched south. While 2022 had a few more cases reported than the year before, 2021 was higher in the number of positive deer. The three highest EHD infection years of the past decade came in 2013, 2015 and 2018 and (see Table 1). The year holding the record for most cases reported with 977 reports remains 2012.

What is EHD?

EHD is an acute, infectious and often fatal viral disease of some wild ruminants, including white-tailed deer. Characterized by extensive hemorrhages, this disease has been responsible for significant outbreaks in deer in the northern United States and southern Canada. Affected animals develop a fever, and typically many are found in, or adjacent to, water where they try to reduce their body temperature. Death can come quickly, from 8 to 36 hours after the onset of observable signs, to some infected deer. Other deer may die days or weeks later, and some will completely recover.

A female white-tailed deer stops along a shoreline for a drink of water. The deer has its reddish summer coat and is reflected in the water with large trees and tall green grasses behind her.
Deer infected with EHD have high fevers and are often found in or near water as they try to cool themselves and have easy access to drinking water. Photo by Jonelle Yankovich from Upsplash.

EHD is observed somewhere in Illinois every year, typically where receding water levels provide the muddy shoreline breeding habitat necessary for the EHD vector, a Culicoides biting gnat. EHD is transmitted when a gnat carrying the virus bites a deer. Outbreaks tend to be localized because environmental and habitat conditions play an important role in producing the right mix of virus, high gnat populations and susceptible deer. An insect-killing frost typically ends an EHD outbreak.

Signs of EHD

Signs of EHD appear about seven days after the deer has been bitten and include sluggishness, difficulty breathing, loss of appetite, salivation and swelling of the head, neck, tongue or eyelids.

A map of Illinois counties showing the 138 reports of EHD infected deer in 2022. There were no reports in northern counties, with distribution through the rest of the state, with higher numbers in central Illinois counties of Macon, Shelby, Cumberland, and Peoria.
Map of EHD reports in white-tailed deer in Illinois in 2022. Map courtesy of the Illinois Department of Natural Resources.

EHD cannot be transmitted directly from deer to deer and is not considered to be hazardous to humans or pets.

The patchy annual distribution of EHD means that Illinois residents are key to tracking annual outbreaks. Illinois residents and hunters serve as IDNR’s eyes and ears in monitoring the annual distribution of this disease, as well as the health of the local deer herd.

To learn more about EHD, or report incidences of sick and dead deer, access the online Report Sick or Dead Deer reporting form at White-tailed Deer Illinois. You will be asked to report facts including the county, number, age, and sex of dead deer and specific location of the deer.

Kaleigh Gabriel is a Wildlife Outreach Specialist with Lewis and Clark Community College, working out of the Illinois Department of Natural Resources building to assist the Division of Wildlife Resources. Growing up just between Sangamon and Christian counties, she spent a lot of her time hunting and fishing in Illinois. She received her bachelor’s degree in writing/journalism from Manchester University, Indiana.

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