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Epizootic Hemorrhagic Disease (EHD)

County Bonus Antlerless Quotas Reduced

County bonus antlerless quotas have been reduced to a maximum of two in areas affected by EHD. Counties that had a county bonus antlerless quota of three or four, have now been reduced to a quota two. Counties that already had a county bonus antlerless quota of two or fewer have not changed. The effects of the harvest and EHD will be evaluated after the season, and additional changes may be made next year if necessary. The Special Antlerless Firearms Season is only allowed in counties marked in green on the Bonus Antlerless Deer Map. Counties with a green designation that are open during this Special Antlerless Firearms Season are: Brown, Clark, Crawford, Floyd, Franklin, Greene, Harrison, Jackson, Jefferson, Jennings, Lawrence, Martin, Monroe, Orange, Owen, Perry, Ripley, Scott, and Washington.

For more information, view the Bonus Antlerless Deer map in the 2019-2020 Indiana Hunting & Trapping Guide.

Both epizootic hemorrhagic disease (EHD) and the bluetongue virus (BTV) are viral diseases that can infect deer, but EHD is more commonly found in white-tailed deer.

Neither EHD nor BTV affects humans.

The clinical signs or symptoms seen in deer typically show up about seven days after deer have been infected with the EHD virus. These signs can include not eating, weakness, loss of fear of humans, circling, and other neurological signs. Deer that have died from EHD may have a swollen tongue, eyelids, neck, or head. The disease is often fatal, but some deer will survive and develop immunity.

EHD is transmitted by biting midges (genus Culicoides) known as “no-see-ums” or gnats. These breed and live in small pools of standing water, pools even as small as a hoofprint filled with water.

EHD can only be diagnosed by a qualified laboratory using blood and internal tissues such as spleen and lung.

Indiana DNR tracks the reports of EHD through online public reporting and, when possible, samples deer in the field to confirm the presence of EHD.

About the Disease

Both Epizootic hemorrhagic disease (EHD) and the bluetongue virus (BTV) can infect deer and are both in the genus Orbivirus. EHD is not normally found in domestic animals (other than farmed white-tailed deer), but antibodies have been detected in sheep, pigs, and cattle. EHD can be found in domestic white-tailed deer. Both diseases are viral in origin, and are transmitted to deer through the bite of small insects called gnats or midges. After the insect population is reduced by cold weather in the fall, the spread of the disease is reduced. Therefore, one should expect new infections to stop shortly after the first hard freeze in the fall.

Hot, dry weather with little rain, often characterized by prolonged summer-like conditions extending into the fall, may increase the occurrence and duration of an EHD outbreak. As usual water sources become scarce on the landscape, more deer use any water that is available. As deer gather around these water sources, more deer in the population may become exposed to infected biting midges, which spread the disease between deer via bites from the insects. Large deer populations can further exacerbate an outbreak as more deer frequent these watering holes.

During the hunting season, if you find a deer that has similar grooves in all its hooves, the animal may have survived EHD infection. The grooves are a result of the deer having had a high fever and is similar to the groove in a fingernail when it grows out after being hit. Such a deer is safe to handle and eat.

Range

EHD and BTV have been known to exist since about the 1890s. The diseases have been found in most of the United States with the exception of the extreme Northeast and the Southwest. EHD has a limited number of host animals. White-tailed deer, mule deer, and pronghorn antelope have been reported to die of infections. Of the three, white-tailed deer is the species most susceptible to EHD.

History

Major outbreaks of EHD have been reported in the United States for decades. Small outbreaks occur yearly in various areas in the United States. Major outbreaks are sporadic occurrences and in many cases do not recur in the same geographic areas. EHD is a naturally occurring disease in our region. Occasionally Indiana DNR receives reports of small, isolated outbreaks. However, major outbreaks are cyclic (about every five years or so). Indiana has experienced two major outbreaks of EHD:

  • 2007: EHD confirmed in 36 counties and suspected in an additional 23 counties.
  • 2012: EHD confirmed in 29 counties and suspected in an additional 38 counties.

Immunity

EHD is an extremely virulent disease. It can be up to 90% fatal in deer showing clinical signs of the disease. The disease is characterized by the rapid onset of clinical symptoms. Some deer can survive the disease. Deer that survive the original infection may become immune to EHD and possibly BTV and will carry antibodies in their blood. In a study completed in the early 1970s in northern Indiana, about 20% of the deer herd was found to have these antibodies in their blood, which indicated the herd had been exposed to EHD and survived.

External Signs

EHD and BTV have similar outward signs. An increase in body temperature can cause deer to seek cool places, such as in and around water.

Outward signs of EHD include:

  • Loss of it appetite and wariness.
  • Swelling around the head and neck.
  • Dehydration and weakness.
  • Increased respiration rate.
  • Excessive salivation.
  • Rosy or bluish color of mouth and tongue.

In prolonged cases, there may be ulcers in the mouth and on the tongue. Blood flecks may occur in the urine and feces. In severe cases, a bloody diarrhea can develop. Deer that are infected may show lameness and a tendency to avoid direct sunlight. Many dead animals are found in or near open water.

Internal Signs

Internal organs will have extensive hemorrhages (bleeding) throughout. The heart, liver, spleen, kidney, lungs, and intestinal tract are most likely to be involved. The liver, spleen, and lymph nodes may be enlarged and congested. Lesions or ulcers may occur on the lips, tongue, and cheeks.

Treatment and Control

There is no treatment for EHD once the animal shows symptoms. There are no preventive methods that are currently being applied to wild populations of deer. According to Infectious Diseases of Wild Mammals (2001), there is no established public health risk associated with handling or eating infected animals or with exposure to infected midges.

Indiana DNR Monitoring

Indiana DNR’s primary method for monitoring EHD outbreaks is through reports of individuals who suspect a sick or dead deer has EHD. These reports are collected through our sick and dead deer reporting form. When possible, fresh dead deer may be sampled for testing by trained staff. Once a county is confirmed to have EHD, Indiana DNR uses the online reporting to monitor the spread and extent of the disease. DNR staff also maintain contact with counterparts in surrounding states to monitor the EHD status more broadly.

Indiana DNR Management

Because EHD is a naturally occurring disease in deer and there is no effective treatment for wild deer, Indiana DNR only monitors for the disease and then assesses the potential effect of the disease on local deer populations as the season progresses. Deer can continue to be infected by EHD for about two weeks after the first significant frost and may be found dead for another couple of weeks. At this point, the hunting season may be underway, and it may be too late to make any changes to current-year harvest regulations.

EHD is not thought to have long-term effects on the deer population size because:

  • Hunters typically harvest fewer deer during a deer season preceded by an EHD outbreak. Deer die from EHD rather than by the annual harvest.
  • When deer populations are lowered (e.g., through disease, high harvest, or other reasons), deer respond by giving birth to more fawns the next year (i.e., a higher birth rate) and typically a greater number of fawns survive to the next year’s hunting season (i.e., greater recruitment rate).
  • EHD events on the landscape tend to be spotty and localized. While EHD may be confirmed in a county, only a small portion of the county may be affected.

When Indiana DNR reviews the effects of the harvest to set the next year’s deer harvest regulations, all known and estimated mortality is taken into consideration, including the harvest, known disease outbreaks, deer-vehicle collisions, and deer depredation permits. If a county has experienced higher than normal total mortality in the deer population, Indiana DNR can make adjustments the next year as needed.