The discovery of thousands of aggressive, fast-reproducing Asian long-horned ticks on a York County cattle farm could have implications for animals and humans in South Carolina, experts have said.
Tick-borne diseases are likely already undiagnosed or unrecognized in the state, and it’s unclear if the new ticks will also cause illness in people, state and national experts said.
Those who do tick monitoring in the state received a call in June about a potential problem on the farm. Once there, they discovered a large number of tiny creatures already swarming among the livestock, said Dr. Melissa Nolan, director of the Vector-borne and Zoonotic Diseases Laboratory at the University of South Carolina.
The state had previously found some of the ticks on shelter dogs in Pickens and Lancaster counties in 2020, but “this is the first time we’ve seen an actual established population of this tick in our state,” a- she declared.
“It’s a significant number of ticks,” said Dr. Linda Bell, state epidemiologist for the Department of Health and Environmental Control. “These ticks are of concern because their bites have caused serious illness in people, animals and livestock in other countries. And they can multiply very quickly.”
The ticks, which are not native to the United States, were first discovered here in 2010 and have spread to 17 states. Although they don’t yet pose a serious threat to humans, they do transmit disease to livestock in other states, said Dr. Michael Neault, a South Carolina state veterinarian and director of the health department of livestock poultry from Clemson University.
Most tick treatments seem to work on them, too, he said.
It’s the female’s ability to reproduce on her own and produce thousands of eggs at once that makes it “such a big deal,” Nolan said.
“You can get thousands of ticks from a population and that’s not normal,” she said. “The problem is that this tick could overwhelm livestock, dogs or people. You could walk around the field and get hundreds of ticks biting you. They are very aggressive feeders.”
Even with optimal protection, the team that went to investigate York’s farm ended up with ticks on it, Nolan said.
Experts who study ticks and tick-borne diseases have observed that the diseases have spread from being more heavily concentrated in the northeast to the southeast states. According to the Johns Hopkins Lyme and Tickborne Diseases Research and Education Institute, southern ticks were considered less aggressive due to climate and tended to feed more on small lizards than humans.
But now, “Southern ticks are being replaced by more aggressive ticks,” said Dr. John Aucott, director of the Johns Hopkins Disease Research Center. The tick-borne disease “is a disease that spreads geographically,” he said.
It’s probably also underreported, not just in South Carolina but nationwide. For Lyme disease, a tick-borne disease, there are officially around 30,000 cases each year, but insurance claims data and other sources suggest that number should be around 300,000. Aucott said.
“We have a problem counting cases,” he said, and there is “vast under-reporting” of these diseases in general. For South Carolina, in 2019, there were 17 confirmed cases of Lyme disease and 30 “probable” cases, according to the Centers for Disease Control and Prevention.
That’s likely an undercount, Nolan said. A study in North Carolina found that only about 20% of tick-borne illnesses are diagnosed and treated.
“That means for every case we identify in the clinic, there are four more cases that are misdiagnosed,” Nolan said.
Tick-borne illnesses must be reported to DHEC and few currently are, “so it’s concerning that we’re running out of cases,” Bell said.
The state advises providers that if patients have unexplained rashes or arthritis-like illnesses with fever and no other explanation, consider seeing an infectious disease expert who may be more familiar with rare conditions like the diseases transmitted by ticks, she said.
Pet owners may want to check themselves and their pets for ticks after walking through wooded or brushy areas, Neault said.
The state would like anyone who finds a tick to send it in to help monitor those ticks and others, Nolan said.