RICHMOND — An infectious virus known as hemorrhagic disease is once again causing white-tailed deer deaths around Virginia, but state wildlife officials say there’s no need to panic.
“It shows up every year,” said Nelson Lafon, the Forest Wildlife Program manager for the Virginia Department of Wildlife Resources.
A blanket term for several related viruses, hemorrhagic disease afflicts wild deer throughout much of the U.S. from the late summer through fall, disappearing as first frosts kill off the tiny biting flies called midges that spread it. In Virginia, it occurs annually in pockets of the Tidewater and Southside regions and occasionally in the Piedmont. Outbreaks are relatively uncommon west of the Blue Ridge but not unprecedented.
Infected deer tend to become feverish and experience difficulty breathing as well as swelling of the head, neck, tongue or eyelids. Some develop lesions that vary widely in terms of severity and number.
One of the most telling signs a deer is suffering from hemorrhagic disease is that “it’s often going to be laying down in water, near water,” said Lafon.
Infected deer are attracted to both water and cool, wet soil because of the high fever associated with the disease.
That symptom often leads Virginians to panic because it is shared by deer suffering from chronic wasting disease, a fatal neurological condition that’s among a family of diseases that includes Creutzfeldt-Jakob disease in humans and so-called “mad cow” disease among bovines.
But while deer afflicted with chronic wasting disease typically appear emaciated when found, deer with hemorrhagic disease “typically appear in good shape,” said Lafon. “They don’t have the skin and bones appearance” seen in animals diagnosed with CWD.
“This is not the same type of disease, and long term we are not near as concerned about it as CWD,” said Lafon.
Also unlike chronic wasting disease: Hemorrhagic disease doesn’t appear capable of transmission to humans, and not all deer that contract it will die, although some will suffer from lasting impacts such as lameness and sloughing of hoofs.
In Virginia, mortality tends to be less than 25% of infected animals in any given outbreak, although more severe outbreaks have occurred. One particularly lethal episode was a 2014 outbreak that caused over 50% mortality in populations stretching in a rough line from the North Carolina border through Richmond and into the Northern Neck.
Research by the Department of Wildlife Resources has found “three potential environmental predictors of (hemorrhagic disease) activity in eastern Virginia: mild winters, hot summers, and a June drought.”
According to the University of Georgia, even repeated outbreaks have failed to decimate deer populations, and cold weather brings the episodes to an end.
With first frosts increasingly creeping backward due to climate change, it’s possible hemorrhagic disease season is slowly becoming longer as the biting midges that spread it have more time to be active.
Lafon said wildlife officials haven’t seen much evidence of an uptick in disease prevalence in Virginia due to later frosts. However, he noted that changing temperatures appear to be driving the spread of the disease northward.
“We’re seeing other states to the north of us are starting to see hemorrhagic disease in places where we didn’t see it a decade ago,” he said.
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