epizootic hemorrhagic disease

There is a confirmed outbreak of epizootic hemorrhagic disease (EHD) among white-tailed deer in the Kingston, Ont. area.

In September, approximately 30 deer were found dead on Wolfe Island. The Ministry of Northern Development, Mining, Natural Resources, and Forestry (NDMNRF) sent a biologist to investigate. Additional sightings in Gananoque Lake, Stirling, and Lansdowne reported dead deer, typically found near water.

The biologist collected an adult buck and a female fawn from Wolfe Island and an adult buck from Gananoque Lake, transporting the deer to the Canadian Wildlife Health Cooperative in Guelph. All three tested positive for EHD.

“EHD is a viral disease that affects mostly white-tailed deer,” says Keith Munro, wildlife biologist for the Ontario Federation of Anglers and Hunters (OFAH). “It has been known to infect some livestock, but it rarely results in symptomatic disease. And it’s not a disease of people. There’s no human health risk.”

This includes consuming deer that has been infected with EHD, Munro adds.

The disease is spread to deer through midges—sometimes referred to in Ontario as ‘no-see-ums’. A midge will bite an infected deer and then transfer the disease when it bites a healthy deer. The midges are carried into new areas on the wind.

Experts are theorizing that the Ontario outbreak has been caused by midges carried up from New York State. According to Munro, the disease is endemic in certain southern states and is beginning to move further north with climate change.

Frost is what kills the disease, Munro says. Experts have observed that approximately two weeks after the first frost, the midges die off, putting an end to the outbreak. “Unfortunately, climate change is contributing to the spread of it because we have longer, hotter summers, but then also we have delayed winters, so the outbreaks can go longer,” Munro says.

Symptoms of EHD can include loss of appetite, no fear of people, swelling of the head and neck, respiratory distress, and extensive internal hemorrhaging. Munro adds that deer killed by EHD are often found near water. “EHD leads to fever, so animals go to water to try to cool themselves down and die there.”

Symptoms emerge in a deer approximately seven days after it’s been infected. From there, it can be anywhere between eight to 36 hours before the deer dies.

Munro stresses that while some of these symptoms are similar to Chronic Wasting Disease (CWD), a disease caused by a folded protein that can be extremely difficult to get rid of, they are different. “With EHD, generally, those animals will look healthier. They will be salivating, but they’ll look healthier, as opposed to the Chronic Wasting Disease ones. They look skinnier and unhealthy,” he says.

There are no preventative measures or treatment for EHD, Munro says. Instead, OFAH is focused on tracking the disease and ensuring ecologically sustainable levels of deer population.

“Those sorts of populations, the sustainably managed ones, they are more resilient to disease,” he says. This is because there’s more food available to a smaller, controlled deer population, making the animals healthier overall.

In some southern states, deer have developed immunity to the disease, but in the north, where the disease is rarer, deer populations are more greatly affected. For example, in 2012, approximately 15,000 deer died from EHD in Michigan, Munro says.

If you come across a dead deer or a live deer exhibiting symptoms, report the sighting to the CWHC at http://www.cwhc-rcsf.ca/report_and_submit.php.

“Public reporting is incredibly important,” Munro says, “both to identify new things that pop up, but also to estimate the extent of outbreaks where they do occur.”

Nature scrapbook: Meet the white-tailed deer