Parasite-borne diseases are raising concerns among researchers after a new type of heartworm was recently discovered in East Tennessee. The discovery occurred after a black bear was found dead in the Smoky Mountains about two weeks ago. Researchers found that the bear was harboring a non-native heartworm.
“Snails and slugs are the … intermediate host, and it causes a really severe lung infection that often leads to fatality,” said Richard Gerhold, an assistant professor at the University of Tennessee’s College of Veterinary Medicine.
The heartworm, Angiostrongylus vasorum, also infected a coyote in Campbell County near the Kentucky border. It affects dogs, but does not infect humans, Gerhold said on a webcast.
Lyme-disease carrying ticks are also cropping up in East Tennessee where, Gerhold said, they had not been just 10 years ago. The black-legged deer ticks are now “well-established” in Oak Ridge, and testing in Claiborne and Campbell counties show coyotes testing positive for Lyme disease about 44% of the time.
“We are no longer free of Lyme disease and I would suspect in the next five years or so, we would consider Knox County endemic, which means greater than 5% of dogs being positive. In dogs, luckily we have a vaccine,” Gerhold said.
He recommends East Tennesseans always apply a preventative medicine to their pets, and that humans also check themselves for ticks after spending time outdoors.
“If you’re walking on a trail, the most likely place for you to pick up a tick is just off the side of the trail,” he cautions.
Gerhold’s research also involves other kinds of ticks, including invasive species like the longhorn tick, which emerged in the U.S. in 2010. Since then, it has spread to more than 13 states, including East Tennessee. The Asia native tick resembles a poppy seed in size and appearance and has been documented so far on humans, pets, wildlife and livestock across the country.
We are no longer free of Lyme disease. — Richard Gerhold, University of Tennessee
Being able to identify ticks is important, because they don’t all cause the same kinds of symptoms or illnesses. According to the CDC, for example, the Lone Star tick has not been shown to spread Lyme disease, but can cause a rash for humans. Gerhold urges residents to send suspected ticks to a lab for identification, so their spread can be monitored.
While ticks can directly transmit disease to humans and wildlife, some of the most commonly known tick-borne diseases are indirectly spread from viruses, bacteria and protozoa found in the tick. Most tick-borne diseases can only be spread by certain species of ticks – like the Rocky Mountain Spotted Fever, spread by the American Dog Tick – further emphasizing the need for proper education.
“I know the Rocky Mountain makes you think that it’s not here,” Gerhold said. “It really should be named the Rocky Top Spotted Fever, to be honest with you, because it is much more common in East Tennessee and Western North Carolina than it is anywhere else in the United States.”
The CDC reports that diseases from mosquitoes, ticks, and fleas more than tripled in the U.S. and tick-borne diseases doubled from 2004 - 2016. Gerhold said physicians don’t receive adequate training on parasitic diseases, making treatment more difficult.
The CDC also says that around eight out of ten vector control organizations lack proper funding for vital prevention and control services to mitigate the spread of these diseases.
“It’s one of those things where I think it comes from educating our policymakers,” Gerhold said. “It’s probably the most important thing we can do.”
(This story was corrected to say the longhorn tick is an invasive species.)
