Deer Diseases
Health FAQs
If you have seen or harvested a sick deer, please call your local District Biologist or the Wildlife Helpline at 1-866-318-2401.
Signs to look for:
- Isolation from other animals
- Listlessness or showing little or no interest in their surroundings
- Lack of coordination
- Frequent lowering of the head
- Blank facial expressions
- Walking in set patterns
- Drooling and grinding of teeth
- Drinking lots of water and increased urination
- Low weight
For more information, see our Chronic Wasting Disease Fact Sheet (PDF).
When dressing/butchering a deer that I harvested, I found several "grubby-looking" larvae in the deer's chest cavity and/or coming out of the deer.
Grubby-looking Larvae
What you are likely observing are bot fly larvae (genus Cephenemyia). These larvae are very common in white-tailed deer. The larvae originate from the deer's sinus cavity, nasal passages and/or pouches in the throat region. When a deer’s body cools down, these larvae sometimes migrate into the throat region. The larvae then typically migrate down the throat and into the open body cavity of a field-dressed deer. It is here that unsuspecting hunters often find the larvae. The larvae are sometimes found in the mouth or nasal region of the deer. Hunters who wait several hours before field dressing and/or butchering the carcass are more likely to find the larvae due to the time it takes for the carcass to cool down and the larvae to migrate out of the sinus, nasal and/or throat region(s).
The larvae typically cause little or no harm to the deer, except for some minor discomfort associated with irritation of the sinuses and nasal passages. The larvae do not in any way make the carcass unfit for human consumption. For those that are concerned about bot fly larvae, immediately removing the harvested deer’s head will keep the larvae from coming into contact with edible portions of the carcass.
I harvested a deer that has a few wart-like growths on its skin. The growths are dark in color and appear to be associated only with the deer’s skin. What are these, and do they make the meat unsafe to eat?
Wart-like Growths
The wart-like growths are most likely cutaneous fibromas. Cutaneous fibromas are caused by a virus, and they are relatively common on white-tailed deer. The growths can range in size from a fraction of an inch to several inches in diameter. Infected deer typically have five or fewer tumors, but more than 200 tumors have been observed on some animals. Although the tumors can be found on any area of the body, they are found most commonly on the head, neck, shoulders and forelegs. The tumors typically do not cause any harm to the deer, and they usually regress and eventually disappear with time. The virus that causes them to grow in white-tailed deer does not infect other wild animals, domestic animals or humans. Cutaneous fibromas are confined to the skin and are removed when the deer is processed for consumption. Unless there is evidence of secondary bacterial infection in the underlying tissues, the animal can be skinned, butchered and consumed as normal. Although the tumors may be grotesque in appearance, they do not affect the quality of the meat.
Commonality of Piebald and Albino Deer
Hemorrhagic Disease
Hemorrhagic Disease primarily affects white-tailed deer and is the most important infectious disease of white-tailed deer. Other ruminant species such as elk, cattle, sheep, and goats can also become infected with the disease. Outbreaks occur almost every year in the Southeast. It is caused by either of two closely related viruses, epizootic hemorrhagic disease (EHD) virus or bluetongue virus. Because disease features produced by these viruses are indistinguishable, a general term, hemorrhagic disease, often is used when the specific virus responsible is unknown. Because EHD and bluetongue viruses are transmitted by biting flies, hemorrhagic disease is seasonal and occurs in late summer and early fall.
In some cases, deer affected with Hemorrhagic disease will display little to no symptoms of an infection, especially if they were previously exposed to the disease. If a deer does show signs of infection, these often include: fever, swollen head or neck, loss of appetite, difficulty breathing, ulcers on their tongue or mouth, and an eroded dental pad. Mortality from hemorrhagic disease most commonly takes place near water sources (e.g. pond, lake, creek) because of high fever. Deer that do not have any prior immunity to the disease will typically die within 5-10 days after infection.
The severity of hemorrhagic disease is affected by a variety of factors (e.g. herd density, midge abundance, previous exposure) and mortality rates vary regionally across the state as well as across years. Deer herds that have been previously exposed to hemorrhagic disease can fight off an infection. Meanwhile, deer which have not been previously exposed to the disease are more likely to die from the disease. Normal deer die-offs associated with hemorrhagic disease occur annually in North Carolina, with larger outbreaks occurring periodically every few years.
Hemorrhagic disease does not pose any significant health risks to people and domestic pets. Hunters do not need to be concerned about consuming venison from infected deer. As always, hunters should be cautious of consuming venison from any animal with obvious signs of illness.
Hemorrhagic Disease Flyer (PDF)
Hemorrhagic Disease Report for District 3, 2014 (PDF)
Hemorrhagic Disease 2012 (PDF)
Southeastern Wildlife Disease Study Information on Hemorrhagic Disease of Whitetail Deer (PDF)
Hemorrhagic Disease Outbreak in NC 2012
Hunting and West Nile Virus
West Nile virus is an infectious disease of birds that can also infect humans. The virus is transmitted by mosquitoes. According to the North Carolina Division of Public Health, West Nile virus may cause flu-like symptoms in humans, such as headache, swollen glands and muscle aches, as well as a rash. Usually West Nile virus only causes mild disease in humans, but in rare cases the virus may cause encephalitis and even death. Elderly people and those with compromised immune systems are most likely to be severely affected by West Nile virus.
Cutaneous Fibromas
utaneous fibromas are wart-like growths that develop on the skin. In deer, these growths are caused by a strain of the papilloma virus that is spread by biting insects. White-tail deer are primarily affected by the virus, but it has been reported in other cervids (deer, elk, moose, etc). While unattractive, fibromas only impact the skin and not the overall health of the deer. Harvested deer are safe to eat unless a fibroma has developed a secondary bacterial infection.
Many species can develop fibromas from various viruses. The virus that causes fibromas in white-tailed deer can only be spread to other cervids.
Cutaneous fibromas are characterized by hairless, wart-like growths on the skin that vary in white, gray or black coloration. Fibromas can vary greatly in size and grow to be 8 or more inches in diameter. The growths can be solitary or found in clusters.
Fibromas generally do not impact the health of the deer and can even clear up on their own. They can become problematic if they impede the deer’s ability to eat, breathe, or see.
People, livestock and pets cannot contract the virus that causes cutaneous fibromas. /p>
Nasal Bots
Nasal bots are the larvae of a maggot style fly in the genus Cephenemyia. An adult fly will lay a group of eggs around the nose or mouth of a deer and the eggs are released when the deer licks the eggs. The larvae then move to the nasal passages and sometimes the sinuses where they develop into larger stages of mature larvae. Once fully mature, nasal bots will exit the deer, pupate in the ground for 2-3 weeks and emerge as adult flies.
Many wildlife species and humans can be hosts of bot flies. Different species of bot flies affect different wildlife species. Bot fly larvae found in white-tailed deer only affect members in the deer family (white-tailed deer, elk, mule deer, etc.). Other wildlife species that are commonly seen with bot fly larvae include squirrels and rabbits.
Bot fly larvae are white to yellowish-brown in color and range from 1-2 inches in length.
The larvae typically cause little or no harm to deer, except for some minor discomfort associated with irritation of the sinuses and nasal passages. Some sneezing and coughing in deer is assumed to be the result of nasal bots. No sores, infection or other problems have been reported even when the parasites are large in number.
Nasal bots that occur in deer do not affect humans or pets. However, there are species of bot flies that can affect human and pets. Cases in pets are uncommon and the fly species that can affect humans only occur in Mexico and Central America. Nasal bots that occur in deer are most often encountered by hunters while field dressing a deer. When a deer’s body cools down, these larvae sometimes migrate into the throat region or into the open body cavity of the deer. It is here that unsuspecting hunters often find the larvae. Nasal bots do not make the carcass unfit for human consumption.
COVID-19
The SARS-CoV-2 virus, that causes COVID-19 in humans, has been detected in wild white-tailed deer inIowa and Ohio. Some states began testing live deer following initial work by the US Department of Agriculture that confirmed the susceptibility of captive deer to the virus and still other research that detected antibodies to the virus in wild deer in Illinois, Michigan, New York, and Pennsylvania. So far, COVID testing in wild deer has been limited to only a few states, but increased testing is occurring locally and nationally.
COVID-19 Precautions for Handling and Processing Deer (PDF) December 2021