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Wildlife Diseases

Two white-tailed deer from London, Ontario have tested positive for Epizootic Hemorrhagic Disease (EHD), which marks the first detection of the disease in wild deer in Ontario. EHD and bluetongue are similar viruses that target white-tailed deer, (which are most susceptible) mule deer, pronghorn antelope, cattle, goats and sheep. The virus is spread by blood-feeding biting midges (also known as “no-seeums”), but cannot be transmitted from deer-to-deer. Once infected, deer may develop fever, have trouble breathing, and seek out water to cool themselves. Deer with EHD are often found dead or dying in and around water. EHD and bluetongue are not known to cause disease in humans and hunters should know that the venison (deer meat) is safe to consume. If you see sick or dead deer, please report it to:

The Canadian Wildlife Health Cooperative
Phone: 866-673-4781


The Ministry of Natural Resources and Forestry
Phone: 1-800-667-1940



• EHD and bluetongue are very similar, possibly related, viruses.
• Vector: biting midges belonging to the genus Culicoides.

Disease Distribution
• Found worldwide in warm climates. Northern limit of vector’s range is limited by climate, which is predicted to change. As more areas become suitable for midges, we will likely see more frequent outbreaks of EHD in Ontario.
• The virus was found in biting midges in Ontario in 2015, but this is the first confirmed case in wild deer.

Susceptible Species
• White-tailed deer seem most susceptible, but also mule deer, pronghorn antelope, cattle, goats, and sheep. Animals can recover from infection.
• These viruses are not known to cause disease in humans.

Timing of Outbreaks
• Outbreaks and deer mortality occur in late summer/early fall when seasonal midge activity is at its peak.

Disease Transmission
• Female midges feed on infected animals, then transmit the virus to uninfected animals through feeding.
• Infected midges can be blown long distances by the wind.
• The disease is not contagious to humans, and it is not transmitted from deer to deer – it requires the midge vector.
• Midges die off during the first frosts, taking the virus with them.

• Onset of the disease is very quick – clinical signs appear ~ 7 days after infection, but some animals do not exhibit symptoms.
• Lethargy, weakness, loss of appetite, loss of fear of humans, breathing problems, excessive salivation, and hoof abnormalities. Some deer will develop ulcers in mouth and on the tongue, and some will bleed from the nose and/or mouth. When fever sets in, deer seek out water, which is why dead deer are often found near water sources. Extensive hemorrhaging affects almost all organs, including the heart, liver, spleen, kidneys, lungs, and intestinal tract.

What To Do If You Find A Dead Deer
• Hunters – the meat is safe to consume and EHD does not infect humans. However, individuals handling sick or dead animals should wear protective clothing, gloves and wash hands thoroughly.
• There is no known strategy to manage EHD or BT in wild deer populations. Insect control might help on a local level, but is likely impractical at the scale required.

External Links

Fatal Deer Disease Reaches Ontario for the First Time

Hemorrhagic Disease of White-tailed Deer (brochure)

What is EHD? Epizootic Hemorrhagic Disease  Explained

Epizootic Hemorrhagic Disease (EHD) in White-tailed Deer

Epizootic Hemorrhagic Disease

Diseases Caused by the Epizootic Hemorrhagic Disease Virus Serogroup

Can We Prevent EHD?


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