EHD A Bit “Ho-Hum” In The Deep South

We are at a point where it would be safe to say that this year’s outbreak of Epizootic Hemorrhagic Disease (EHD) is quite widespread. Here’s a list of states that have confirmed cases of the virus that is carried to deer by biting midges or no-see-ums: Virginia, West Virginia, Indiana, Kentucky, North Carolina, Tennessee, Alabama, Pennsylvania, Ohio, Illinois, New Jersey, Montana, Mississippi and Georgia. In addition, some states are waiting for test results to confirm what they already suspect - South Carolina is one such state.

To confirm the presence of the disease, blood and certain tissue has to be analyzed.

According to both the South Carolina Department of Natural Resources and the Alabama Department of Conservation, dealing with EHD is quite routine. Charles Ruth, Deer/Turkey Project supervisor for the South Carolina DNR says flair-ups in that state seem to run in cycles of 3-5 years and there’s a reasonable explanation.

“This is probably related to the fact that once deer are exposed to the disease they are more resistant to it. Therefore, if you have disease one year the deer become exposed or inoculated to the disease and you do not see much disease activity until there is turnover in the deer population. After several years you are dealing with another cohort of deer and their systems are ‘naïve’ to the disease. The last time there was significant hemorrhagic disease activity in South Carolina was in 2002, therefore, disease activity could be relatively high this year.”

This theory is confirmed by a spokesman for the Alabama Department of Conservation and Natural Resources.

“We have some cases every year,” said Keith Guyse, a whitetail specialist with the Wildlife and Freshwater Fisheries Division in the Alabama Department of Conservation and Natural Resources. “In the Coastal Plain, the virus is there frequently enough that deer have been exposed to it and have some resistance to it.

Both representatives indicate that EHD in their respective states is pretty much routine only because of the build up of a certain degree of immunity. Therefore, these southern states don’t see wide outbreaks of the disease that often. When EHD hits the more northern climes, EHD seems to grab harder. Ruth explains.

Deer likely die in South Carolina each year from hemorrhagic disease, however, there is no indication that a major outbreak has occurred in the state since the mid 1970s. The disease is part of life for deer in the Southeast and fortunately it appears that Southern deer have acquired some immunity to the disease, said Ruth. Northern deer, on the other hand, are not exposed to the disease as frequently since the insect vector is not as common in cooler climates. For this reason, significant outbreaks and mortality from hemorrhagic disease are more likely in northern deer populations.

Guyse from Alabama makes reference to the same theory.

“Typically in North Alabama and above the fall line, they’re not exposed to it as often. So over a period of time you have a population that doesn’t have much resistance. When you have (outbreaks) up there, it tends to be more noticeable.”

This helps us understand why some states may have more severe outbreaks, killing larger numbers of deer, than others but why this year are outbreaks so widespread across the landscape of the country? Some have related it to the summer heat and drought. That may be true, I don’t know. It would be logical to assume that being that the virus is carried and spread by tiny midges or gnats, a larger than normal population of that insect would be directly proportional to the spread of the disease. Of course science isn’t that simplistic and we know that there are probably many more factors to consider or it could be just merely a coincidence.

However, Guyse from Alabama eludes to the theory of increased numbers of midges, somewhat.

“Auburn (researchers) had traps out to catch the flies and they might catch a few every once in a while, and then all of a sudden they catch hundreds,” Guyse said. “Much of that still is a mystery.”

Obviously, they don’t have a good handle on it either.

Hunters and others should be aware of the symptoms they may find on deer suffering from the disease.

Symptoms of hemorrhagic disease include poor physical condition, sloughing hooves, abrasions or sores on the brisket and legs, and ulcerations on the mouth, tongue, and rumen (stomach).

As I said earlier, verification of the disease has to be done in the lab.

If you see sick or dead deer in your travels, please report it to the appropriate authorities. It is highly recommended that nobody eats any of the meat from deer sickened by EHD.

Tom Remington