Asian longhorn tick continues to spread

Parasite first found in New Jersey, yet to be found on the Vineyard.

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A foreign tick is spreading in the U.S., threatening livestock and people. First discovered in New Jersey in 2017, the Asian longhorn tick (Haemaphysalis longicornis) has since been found in Virgina, New York, Pennsylvania, and several other states. So far, it hasn’t been encountered in Massachusetts.

“Not that we know of,” said entomologist Larry Dapsis, Barnstable County’s tick project coordinator. But Dapsis said the arrival of the tick in the Bay State was inevitable.

Native to East Asia, the tick prefers sheep, horses, and cattle as hosts, but does bite people.

The tick can transmit bovine theileriosis and babesia protozoa, according to a bulletin from the Northeast Regional Center for Excellence in Vector-Borne Diseases.

“Bovine theileriosis can reduce dairy production on cattle farms, and occasionally kill calves. The ticks themselves can also cause anemia in sheep and cattle, when densities are high,” the bulletin states.

Bites from the tick may also transmit diseases to people. “In Asia, field-collected longhorn ticks can harbor pathogens that are also present in, or closely related to, those found in the U.S.,” the bulletin states. “These include Anaplasma phagocytophilum, Ehrlichia chaffeensis, Babesia species, and Powassan virus. The capacity of this tick to act as a vector for these pathogens has not been studied. This species is also considered a possible vector for thrombocytopenia syndrome virus (SFTSV) in China, an emerging infectious disease with a reported human mortality rate of up to 12 percent.”

Dapsis said he is not particularly worried about the tick becoming abundant on the Cape due to the thin amount of livestock there, but he noted the tick “could be impactful” on the Vineyard and Nantucket because of their heavy deer populations. The tick poses a serious threat to dairy farmers in Western Massachusetts, he said.

“It’s probably on our doorstep,” he said.

Biologist Dick Johnson, who runs the Island tick program via Dukes County, described the rapid expansion of the tick as “pretty shocking.”

He’s yet to see the tick on the Vineyard, he said, and noted he goes to great lengths to identify any unusual ticks uncovered in yard surveys.

Lorenza Beati Ziegler, curator of the U.S. National Tick Collection at Georgia Southern University, described the Asian longhorn tick as “very tenacious” in its capacity to overrun an area. She said this was due to parthenogenetic reproduction — female Asian longhorns do not need to mate with males in order to produce offspring.

“We’d never seen anything like it,” Heather Szerlong, co-founder and CEO of Ticknology, a Colorado tick surveillance and testing company, told The Times. Last month an Asian longhorn tick was mailed out to Ticknology from New Jersey. Ticknology was able to identify it with cooperative research from Rutgers University. “They’re very hard to identify because they’re very hard to differentiate from other ticks of that genre,” she said.

The tick her company received turned out to be the first known case of an Asian longhorn tick in Bergen County, New Jersey. The tick was found on a girl in her early teens. What was exceptionally notable, Szerlong said, was the teenager hadn’t had any contact with livestock, making it a first in the U.S. Last year the tick came into the public eye after farmers in another county in New Jersey recounted how while shearing sheep, they got ticks all over themselves, she said.

“It’s not just a farmer’s issue,” she said. “They might be discovered in rather manicured areas.”

Reached Monday afternoon, Clarissa Allen, owner of the Allen Sheep Farm in Chilmark, hadn’t heard of the Asian longhorn tick, but noted that aside from lack of rain, nothing was amiss with her flocks. “We haven’t experienced any problems with anything on our sheep,” she said.

Szerlong said the tick found in Bergen County tested negative for pathogens. But at this point she emphasized that what these ticks may or may not harbor is still an unknown, as is much of their behavior. “There’s a lot to learn yet,” she said.

Dapsis said his focus remains on the black-legged or deer tick, the vector for Lyme.

Wherever folks might travel in nature, he said, the best protection against ticks is permethrin-treated clothing.