Wisconsin deer EHD outbreak; cases climb, identified in Dodge County

MILWAUKEE - The Wisconsin Department of Natural Resources estimates there have been more than 100 additional cases of epizootic hemorrhagic disease in the past week as an outbreak continues to spread among wild deer in southeast Wisconsin.

EHD case estimates

By the numbers:

The DNR is monitoring an epizootic hemorrhagic disease – or EHD – outbreak that was first reported in Washington County deer. Suspected cases have since spread to surrounding counties.

FREE DOWNLOAD: Get breaking news alerts in the FOX LOCAL Mobile app for iOS or Android

As of Sept. 15, the DNR estimates the total number of sick or dead deer with signs of EHD to be:

• Dodge County: about 20
• Milwaukee County: less than 10
• Ozaukee County: just over 30
• Washington County: just over 900
• Waukesha County: just over 200

The previous report, Sept. 8, did not identify any cases in Dodge County. Cases in Washington County were estimated at just over 755 at that time, with just over 175 in Waukesha County, just over 30 in Ozaukee County and less than 10 in Milwaukee County. An initial report in mid-August estimated "as many as 100" deer had died from EHD.

What we know:

Erin Larson, a DNR deer herd health specialist, told FOX6 News last week that the number of suspected cases during the outbreak far exceeds previous years' outbreaks.

Typically, the first cases of deer that have died of EHD are reported in September, but this year, reports began rolling in at the beginning of August.

SIGN UP TODAY: Get daily headlines, breaking news emails from FOX6 News

According to Larson, this could mean a higher overall count at the end of the season. However, she has reassured that despite the high number of deer deaths, herds are usually able to bounce back from the population decrease rather quickly. 

What we don't know:

It still remains to be seen what the total number of deceased deer from the outbreak will be. 

What is EHD?

Dig deeper:

Epizootic hemorrhagic disease, or EHD, is a virus that impacts white-tailed deer and other hoofed animals, according to Wisconsin DNR. The disease is most often fatal and usually kills the animal within a week of infection. 

It is caused by either the bluetongue virus (BTV) or the epizootic hemorrhagic disease virus (EHDV). When the disease regularly occurs in a deer herd population, death rates are lower, typically killing less than 25% of the deer population. 

However, in areas like Wisconsin, where the disease is less common, death rates are usually higher, and high-density herds will suffer higher fatality rates. 

EHD is transmitted by biting flies, usually midges, so the disease is typically most prevalent when the fly population is most abundant, in late summer and fall. The virus cannot last long outside the insect or its host. 

Can people or pets get EHD?

Why you should care:

The disease does not pose a risk to humans. Humans cannot contract the virus by handling infected deer, eating venison, or being bitten by infected insects. 

It also does not impact common household pets, such as cats and dogs, according to Idaho Department of Fish and Game.

EHD symptoms in deer 

Clinical Signs:

It is virtually impossible to distinguish between hemorrhagic disease caused by BTV or EHDV. Symptoms of the infection in deer vary depending on what stage of the disease the deer are in and how long they have been infected. 

Potential signs of infection include: 

• A lack of fear of humans
• Excessive salivation
• Foam present around the nose (sometimes with blood)
• Look weak despite having a good body condition
• Appear to have parts of the body swollen (usually the head and neck)

The deer will also often appear near water sources, as they head there to try to combat their high fevers and dehydration. 

EHD in Wisconsin 

Timeline:

Wisconsin deer were first confirmed to have EHD in the fall of 2002 when 14 deer were found dead suddenly in Iowa County. Blood samples from deceased deer were collected and tested between 2002 and 2011 and the results did not find antibodies to BTV or EHDV. 

This implies that Wisconsin deer are not exposed routinely enough to these diseases to have developed any antibody resistance. Some deer, such as those in the southern and western U.S., have built up more antibodies against these viruses. 

Outbreaks have varied in the number of deer killed by the viruses throughout the years. One of the most fatal outbreaks in recent years was in 2019. Crawford, Grant, Iowa, La Crosse, Richland, Sauk, and Vernon counties reported deer deaths ranging from 1 to 226 per county. The highest number of deer deaths were seen in Crawford County. 

The identification of EHD happened in 1955 in both New Jersey and Michigan, according to the Michigan DNR. Hundreds of white-tailed deer had died of the disease, which had not been seen before.

Reporting sick or deceased deer 

What you can do:

If you spot a deer carcass or a deer that appears sick, you can report this to the Wisconsin DNR by emailing the agency at DNRWildlifeSwitchboard@wisconsin.gov or by calling 608-2267-0866. 

When you contact Wisconsin DNR, they ask you to include the following information: 

• The number of dead deer
• If the deer is sick or dead
• The specific location where you saw the deer, including the county
• Your contact information

You do not have to report deer that you see killed on the roadway for health reporting. The department also does not have the resources to remove the dead deer.