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Hemorrhagic Disease in white-tailed deer (often called "blue tongue") is caused by viruses transmitted by small, biting flies. Populations of these biting flies peak in summers with a lot early rainfall followed by dry weather, creating ideal environmental conditions for their reproduction. Affected deer seek out water to drink or cool off, which is why many infected, deceased deer are found near streams or ponds. Hemorrhagic Disease is fatal to some deer, whereas others develop resistance and pass that on to their offspring. After the first hard frost kills the biting flies, reports of sick deer rapidly diminish. Hemorrhagic Disease is generally reported in late summer and early fall in Kentucky. Large-scale outbreaks typically occus every 5-10 years, although some reports of suspected cases are received by Kentucky Fish and Wildlife every year and localized outbreaks occur sporadically.
Updated: October 2, 2024
The Kentucky Department of Fish and Wildlife Resources' Wildlife Health Program has received confirmed cases of hemorrhagic disease and is seeing an increase in suspected cases in white-tailed deer.
Clinical signs vary and range from rapid death to lingering effects in some individuals. Deer infected with these viruses may be depressed, feverish, emaciated (very thin), and remain near water in late summer or early fall.
Acute form:
Lingering form:
Lesions
Lesions vary depending on the virulence of the disease. They include edema (swelling) of the head, neck, tongue, conjunctiva, lungs, heart, rumen, and intestines. There may be ulcers in the dental pad, tongue, palate and stomach (rumen and omasum chambers in particular). More chronically-infected deer may have growth interruptions in the hooves or sloughing of hoof walls.
This disease is diagnosed from a blood sample, or from a refrigerated sample of spleen, lung, or lymph node tissue.
Hemorrhagic Disease occurs frequently, but its severity and distribution are highly variable. Past occurrences have ranged from a few scattered cases every year or two, to dramatic regional or statewide outbreaks every 5-10 years, as in 1997, 2002 and 2003, 2007, 2012, and 2017. Death rates are usually are well below 25% of the population, and no deer population has ever been wiped out by Hemorrhagic Disease, even back in the 1950’s when it was first described and deer numbers were much lower!
There are no known treatments or controls for Hemorrhagic Disease.
Hemorrhagic Disease is one of the most important diseases affecting white-tailed deer populations in Kentucky and throughout the Southeast. The disease affects deer throughout the Southeast and much of the rest of the country. It probably occurs at a low rate every year, but some years an outbreak may occur, resulting in a large number of deer deaths that are noticeable to the public. Outbreaks are more likely to occur in the northern and more mountainous areas of the range of the disease; however, they are still relatively uncommon.
At present there is little that can be done to prevent or control this disease. As with most diseases and parasites of white-tailed deer, impacts will be minimized in deer herds that are maintained at moderate to low densities. The best and only practical means of regulating deer populations is through recreational deer hunting, including the harvest of antlerless deer. Although die-offs of deer due to Hemorrhagic Disease often cause alarm, past experiences have shown that mortality will not decimate local deer populations and the outbreak will be curtailed by the onset of cold weather.
While elk in eastern Kentucky can contract the disease, they usually show no outward signs of illness. Hemorrhagic Disease is typically not fatal for elk. Additionally, while livestock may be exposed to the disease, they do not usually die from it.
The viruses that cause hemorrhagic disease do not infect humans, and people will not contract these diseases from eating meat from infected deer. Deer with hemorrhagic disease may be more susceptible to other diseases, however, and consumption of a sick-looking animal is not advised.
Please contact our Information Center at 1-800-858-1549 or Info.Center@ky.gov if you have any questions not answered below.
If you found an injured animal, contact a permitted wildlife rehabilitator. A licensed rehabilitator can evaluate and treat an animal to release back into a natural habitat. If you have found an injured deer, contact the county's regional biologist.
No. Seasons and deer harvest limits will not change. Biologists estimate Kentucky’s deer herd at 1 million animals prior to the start of the seasons. Most deer will not be affected. After the first hard frost, the insects which carry the disease will die off and the outbreak will stop. Herd numbers typically rebound quickly after an outbreak. Hunters can enjoy the deer season as usual. Animals that recover are safe to eat since the virus cannot be transmitted to humans.
While elk in eastern Kentucky can contract the disease, they usually show no outward signs of illness. Hemorrhagic Disease is typically not fatal for elk.
No. While hemorrhagic disease does cause mortality among white-tailed deer herds, there are also animals that survive and produce protective antibodies, which can be passed to offspring. This is an important distinction compared to chronic wasting disease (CWD), which is always fatal. Chronic wasting disease poses a real and significant threat to the commonwealth’s cervid population and should not be confused with hemorrhagic disease.
Hemorrhagic Disease affects deer in Kentucky every year. More severe outbreaks may occur statewide every 5 to 7 years. Outbreaks can be major, but the population rebounds quickly. Only a fraction of the deer population is affected even in years with major outbreaks. Some deer will contract the virus and survive.
Hemorrhagic Disease occurs in cyclical outbreaks, with the last large scale regional outbreak reported in eastern Kentucky in 2017. The disease occurs across the country and has been documented for more than 60 years.
The first hard frost will kill the gnats which carry the disease. This will stop outbreaks.
Hemorrhagic disease cannot be prevented or treated. Kentucky Fish and Wildlife tracks reports from the public and tests sick deer for the virus when possible.
Please report unexplained deer deaths or sickness using the online form. If near a home or business, you can bury the carcass or cover it with lime to reduce the smell. Remove it from any body of water that is a drinking water source.
No. Landowners may leave carcasses to decompose naturally or dispose of them if they wish to. If you see a carcass on a road or roadside, please contact the county road department.
Livestock can be exposed to the disease, but do not usually die.
2017 EHD Summary DOWNLOAD
2019 EHD Report Status Map DOWNLOAD
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