The scene could be plucked from science fiction. Or maybe a horror movie.
Picture hundreds of ticks swarming over a horse’s head in Virginia’s Warren County and thousands crawling up a New Jersey woman’s arm as she shears her sheep.
The longhorned tick has been known to spread deadly disease in its native eastern Asia, but it was only identified in the U.S. last summer, when that New Jersey woman showed up to her local health department with unidentifiable ticks all over her clothes.
Then it turned up on an orphaned calf in Albemarle County in May, and has since been identified in nine other Virginia counties.
The longhorned tick is smaller than average, tends to be found in large numbers and is shrouded in mystery. This time last year, entomologists were blissfully unaware that it had invaded the U.S. at all, but now it’s also been spotted in West Virginia, North Carolina, New York and Arkansas.
“And that pattern pretty much indicates that the tick has been here much longer than we initially thought,” said Theresa Dellinger, assistant lab manager at the Virginia Cooperative Extension.
Researchers are still trying to figure out how it got to the U.S. in the first place, though it has already invaded Australia and New Zealand.
But the longhorned tick has other odd qualities, like the fact that only females have been found in the U.S. because they are parthenogenic, meaning they can reproduce without males.
“That is a little weird, even for ticks,” Dellinger said.
And though they are smaller than average, the longhorned tick has a powerful bite that a person can feel, said Elaine Lidholm, director of the office of communications with the Virginia Department of Agriculture and Consumer Services.
“It’s not a pleasant thing, that’s for sure,” Lidholm said. “And the problem with an invasive species, whether it’s a plant or animal or insect, is that generally speaking there are no natural predators. We don’t know that there’s a beetle out there that would eat these ticks.”
But longhorned ticks have an even more sinister side. In Asia, they carry diseases that can be fatal to humans, particularly SFTS, (severe fever with thrombocytopenia syndrome) which can cause severe fever and very low blood platelet counts, leading to organ failure. It kills between 6 and 30 percent of those infected.
It’s not clear yet if the longhorned tick spreads any diseases in the U.S.. Researchers at the CDC, the U.S. Department of Agriculture and Rutgers University are currently investigating if it does spread disease and how widespread it is in the U.S.
The CDC has been testing identified longhorned ticks for pathogens and is working on creating a research tick colony in its lab, a spokesperson for the agency said in a statement.
At the moment, the longhorned tick doesn’t seem to be anything more than a nuisance for livestock, though the Virginia Cooperative Extension’s website notes that an animal “may carry such a high tick load that they lose weight and become anemic.”
Meanwhile, ticks in general are becoming a more serious problem for people in many parts of the country.
According to the Centers for Disease Control and Prevention, between 2004 and 2016 incidents of tickborne diseases like Lyme disease have more than doubled. That could be because winters are growing more mild, though Dellinger noted that many ticks can survive the winter cold. She said people may be seeing more ticks as white-tailed deer move into urban areas, bringing ticks with them.
According to the CDC, it’s rare that a new tick species is introduced into the U.S., though Virginia isn’t immune to invasive species. The emerald ash borer has killed hundreds of millions of ash trees in North America, and the gypsy moth strips leaves from about two million acres of trees and bushes annually. Just earlier this year, Virginia identified a new invasive pest, the spotted lanternfly. The giant hogweed plant, which can burn and blind people has also gotten headlines.
The longhorned tick has been spotted in 10 Virginia counties: Fairfax, Albemarle, Warren, Page, Louisa, Smyth, Pulaski, Giles, Grayson and Russell counties.