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Minnesota DNR responds to new deer disease in state

The Minnesota DNR says a new disease, epizootic hemorrhagic disease, may impact deer in some areas of the state but that populations will likely rebound quickly. (file / News Tribune)

Minnesota Department of Natural Resources wildlife officials are taking seriously the confirmation earlier this month of a fatal new deer disease in Minnesota, epizootic hemorrhagic disease.

The new malady, which killed six of seven deer in a captive herd on a southern MInnesota farm, already has impacted wild deer populations in several other states, including Montana and North Dakota, in some areas drastically reducing deer numbers.

As the News Tribune first reported Oct. 17, the disease is carried by tiny midges, or gnats, and that may mean other deer in the area around the farm could be infected because the captive deer hadn't been moved in years, said Mackenzie Reberg, Minnesota Board of Animal Health senior veterinarian.

Outbreaks of diseases similar to epizootic hemorrhagic disease have been described since 1890 in the U.S. But the virus that causes epizootic hemorrhagic disease was not isolated until an outbreak in New Jersey white-tailed deer in 1955.

According to Minnesota officials, epizootic hemorrhagic disease affects all members of the deer family, Cervidae, and white-tailed deer are highly susceptible. There are no known health risks to people. Many infected deer die within 36 hours of clinical signs that include fever, anorexia, lethargy, stiffness, respiratory distress, oral ulcers and severe swelling of the head and neck. Sporadic cases occur in other species of cervids and hoofstock. There is no specific treatment or vaccine available in the U.S.

The News Tribune asked Lou Cornicelli, the DNR's wildlife program leader, to field a few questions on the first discovery of epizootic hemorrhagic disease in Minnesota deer:

News Tribune: Did the confirmation of epizootic hemorrhagic disease in deer on a Minnesota farm earlier this month surprise DNR wildlife experts?

Cornicelli: Not really. What's been surprising to me is we haven't seen the disease before now. It's been (confirmed) in the states around Minnesota. The surprising piece is why would the disease show up only in a captive cervid facility in the middle of excellent deer habitat. Although we put the call out for sick wild deer reports, we've had nothing reported to date. Given we've had several nights of cold temperatures (which kills the gnats) we may not see anything this year.

News Tribune: Is the DNR concerned over the potential of EHD in the state's wild deer herd? If so, what steps are you taking to monitor or slow the spread? Any testing planned?

Cornicelli: We're always concerned about diseases that affect deer, and other species. That said, there's no preventative monitoring we can do, other than serological work, which is post-exposure. Where EHD occurs, it tends to show up quickly and cause acute mortality. Given it's vector-borne, there's not much we can do other than ask for people to let us know if they see sick deer. We can ultimately investigate the reports, alert the public, and adjust deer permit allocations as necessary.

News Tribune: While this is the first time EHD has been found in Minnesota deer, it has been widespread across the U.S. for many years. In some cases it has caused dramatic declines in specific wild deer herds, including in Montana and North Dakota. What's the potential for EHD to impact deer numbers in Minnesota?

Cornicelli: EHD most definitely has the potential to impact deer populations over the short-term. In states where it occurs, they have seen substantial declines in the areas where the disease occurs. That said, it's typically short-term and deer populations can rebound relatively quickly.

News Tribune: DNR has been dealing with chronic wasting disease in the state's herd for over a decade now. Is the worst behind us with CWD or is more to come? What have you learned about deer diseases from the CWD effort?

Cornicelli: All diseases behave a little differently. With EHD, the concerns are about short-term declines that happen pretty quickly. With bovine TB, we don't think too much about deer population implications; rather, it's more about cattle and movement restrictions. With CWD, we think more in the long-term. If that disease becomes established and spreads, we'd be in a situation where the deer population is negatively affected over the very long-term. The difference is it takes a long time for the impacts of CWD to be seen, so it's much more difficult to describe and get people to understand. With EHD, potentially large numbers of deer are dead and dying near water — people see that.

News Tribune: It seems like there are more and more wildlife diseases popping up. What other maladies are on DNR's radar that might impact the deer herd in the future?

Cornicelli: You could certainly argue that diseases that climate change may expose northern deer to pathogens they would see otherwise and perhaps EHD is an example. The midge and virus aren't very cold tolerant, so if we have longer periods of above-freezing temperatures, we might see vectors persist where they wouldn't otherwise.