EHD Outbreaks Could Again Affect Deer Populations in Iowa, Illinois, & Wisconsin

I have been deer hunting for many years. I've seen cases of tuberculosis and Chronic Wasting Disease (CWD), but I have never heard of the disease that is currently the topic of an Iowa DNR press release, as most associated deer fatalities occur from July to September.

Epizootic Hemorrhagic Disease (EHD) and Bluetongue Disease (BT) are viral infections affecting deer populations across the United States, including Iowa, Illinois, and Wisconsin. These diseases are caused by closely related orbiviruses and are transmitted by biting midges, commonly known as "no-see-ums." You know the nasty little buggers that bite and annoy us all summer long.

Where as the "no-see-ums" may annoy us, it's a life-or-death situation when our deer are involved. Now the Iowa DNR has called on area hunters, hikers, and outdoor enthusiasts, to help them keep an eye on EHD and BT. In most cases, deer populations generally recover within a few years without management intervention.

That being said, areas of already low deer populations may need help to facilitate a recovery. In areas where infected no-see-ums/gnats are active, up to 90% of the deer population may die, however surviving does have a chance to pass along an immunity to their fawns.

EHD and BT in Deer: A Story of 3 Syndromes

• Peracute Form: This is the most severe form, characterized by sudden high fever, anorexia, weakness, and respiratory distress. Deer may experience severe and rapid swelling of the head and neck, often leading to death within 8 to 36 hours.
• Acute Form: Symptoms include excessive salivation, nasal discharge, hemorrhages in tissues, and ulcerations in the mouth and digestive tract. Deer in this stage may die suddenly or suffer severe internal bleeding.
• Chronic Form: Surviving deer may develop long-term symptoms such as lameness due to hoof issues, emaciation, and scarring of the rumen. In severe cases, deer may lose their hoof walls, making walking difficult.

Deer with EHD often seek water sources in the final stages of the disease, likely due to fever and dehydration. Curious about the damage this disease can cause? Find pictures with explanations here.

Tri-State Impact and Management:

Iowa

In Iowa, EHD tends to surface in late summer and early fall. The Iowa Department of Natural Resources monitors the disease's presence and severity, which can vary yearly. Notably, Iowa experienced a significant EHD outbreak just last year in 2023 with the disease reported across 74 counties and heavily in the Southeastern region. The state emphasizes the importance of reporting suspected cases to help manage and monitor the disease effectively​.

Illinois

EHD was first identified in Illinois in the 1970s. The Illinois Department of Natural Resources collaborates with hunters to report and manage outbreaks. They utilize hunter harvest data and targeted sharpshooting to control the disease's spread and maintain healthy deer populations. They also offer resources for testing and reporting suspected cases. In 2023, Illinois reported 138 cases of Epizootic Hemorrhagic Disease (EHD) across 24 counties, with the highest incidence in Cumberland, Macon, and Peoria counties.

Wisconsin

Wisconsin has also reported EHD outbreaks, with significant impacts on deer populations during severe outbreaks. The Wisconsin Department of Natural Resources (WDNR) provides guidelines for hunters and landowners on reporting and managing suspected cases. Public awareness and participation in reporting are crucial for controlling the disease's spread.

In the past, EHD and Bluetongue outbreaks had a significant impact on the deer population, with approximately 300 deer affected in Crawford and six adjoining counties alone. In 2021 Buffalo County reports indicated around 30 to 35 deer fatalities attributed to EHD. Additionally, cases were observed in Juneau County, though specific figures were not provided​.

There is No Effective Treatment or Prevention

There is no known effective treatment or vaccine for EHD or BT in wild deer populations. Management efforts focus on monitoring outbreaks, reporting cases, and researching the long-term impacts on deer populations. In some states. In cases of Chronic Wasting Disease, sharp shooters are occasionally used to cull sick presenting deer, that practice is not common when it comes to EHD or BT.

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Understanding and managing these diseases is crucial for maintaining healthy deer populations in the Tri-State area. Awareness and cooperation from hunters and landowners is vital to controlling the spread and impact of EHD and BT on our local deer populations. For more detailed information and to report cases, you can refer to the Iowa Department of Natural Resources, Illinois Department of Natural Resources, and Wisconsin Department of Natural Resources.