State faces bear mange epidemic

Harrisburg — Wildlife biologists are seeing a higher incidence of mange among black bears in Pennsylvania than their colleagues in neighboring states, although the reasons are a mystery so far.

“We have more questions than answers at this point,” said Pennsylvania Game Commission black bear biologist Mark Ternent. “We don’t know if it’s just that the population of bears is going up, or if a larger percentage of bears is being affected. But we are seeing more cases every year.”

Ternent is working with researchers at the University of Georgia to determine which lab tests are most effective at diagnosing mange – whether blood or tissue sampling is better – and which species of mite is causing Pennsylvania’s problem. They also want to learn how persistently mites stay in the environment.

Although bears spread mange by contact with each other, particularly during breeding season and in family units, a healthy bear can contract mites by touching a tree, a bird-feeder post, or some other surface that an infected bear contaminated even several days earlier, Ternent said. 

About 50 Pennsylvania black bears a year die of mange or have to be euthanized, he said. 

Mange is known to infect about 100 different kinds of animals, including foxes and coyotes, worldwide, and the mites that transmit the disease are species-specific, Ternent said. 

Black bears are vulnerable to Sarcoptes scabiei, a burrowing mite that creates microscopic tunnels under the skin where it deposits eggs and other debris, he said. “That foreign matter triggers an allergic response because the body is trying to fight off a foreign substance. The skin itches, so the bear scratches and rubs against trees, which damages the skin and causes a secondary bacterial infection.”

Infected bears eat less, which ultimately can lead to malnutrition and a further decline in health, particularly if it is during the fall, when bears are trying to fatten up for hibernation, Ternent said. “It’s a really awful way for a bear to die.”

If an infected bear has more than half of its fur, Ternent will treat it with an injectable pharmaceutical, although the treatment only kills adult mites and not eggs that are incubating in the bear’s skin. “We’ve treated some bears successfully,” Ternent said.

“But if more than 50 percent of an infected bear’s fur is gone, our policy is to euthanize.”

Bear mange first showed up in the 1980s and ‘90s in Blair, Huntingdon and Centre counties, and then began an outward progression, said Ternent. “Interestingly, there hasn’t been a lot of spread eastward. We see it to about Lycoming County, and maybe a little in Sullivan County, but not much in the northeastern counties.”

When Ternent performs his annual late-winter den studies that include ear-tagging bears, he checks for mange, although an infected bear may not yet be symptomatic, he said.

Ultimately, Georgia researchers may provide diagnostic tools that can be used on bears before they show clinical evidence of the disease, he said. “They may be a year or so away from determining whether blood testing or tissue sampling is better.”

Researchers also are working to identify the genetic makeup of mites in Pennsylvania, compared with those in other states, Ternent said. “We may be dealing with a mite that doesn’t occur in other places. Or maybe something in our bear population predisposes them to mange – whether it’s genetic, nutritional, or environmental.”

Humans can play a big role in helping to slow the spread of mange by not feeding bears, said Ternent. “When someone sends me photos of a bear with mange, in the background there will often be a bird feeder, which is only enticing healthy bears to come into contact with sick bears.”

He urges people to stop feeding birds if they live in an area where bears are present. “You want bears to disperse, not congregate,” he said. “Otherwise, you’re jeopardizing a healthy population.”

Hunters and others who come into contact with a bear with mange could pick up the mite, but it doesn’t pose a health threat because it is specific to bears, Ternent said. “If the mite gets onto a person, it may give them a rash like poison ivy. I’ve gotten it. But it’s temporary. Within 10 days to two weeks, your immune system will overcome it.”

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