Asian longhorned tick continues northward march

Invasive arachnid now found in Connecticut, but not yet in Massachusetts.

Asian Long-Horn ticks. –Courtesy Meredith van Acker, Columbia University

Updated April 29

The Asian longhorned tick, an invasive species from East Asia and Australia, continues to spread north, and is now found in Connecticut. As The Times reported last summer, the tick was first discovered on sheep in New Jersey in 2017. It was later found in Maryland, New York, Virginia, West Virginia, North Carolina, Kentucky, and Arkansas. Known to carry and transmit certain diseases in Asia, the tick has not shown itself to be a pathogenic threat to people in the U.S. so far. Much of the worry about it revolves around its potential as a livestock pest.

While it’s not yet found in Massachusetts, its arrival is only a matter of time, Dukes County biologist Dick Johnson told The Times. The two ticks found in Connecticut were both in Fairfield County. One was found during an outdoor tick collection, while another was found on a child who was bitten by it, according to Goudarz Molaei, a research scientist for the Center for Vector Biology and Zoonotic Diseases at the Connecticut Agricultural Experiment Station.

“Luckily we didn’t find any infection,” he said of the tick that bit the child. Molaei not only conducted tests on the tick for local pathogens but ran special panels for pathogens not found in the U.S. He noted that in Asia, the tick has been shown to harbor strains of babesiosis, anaplasmosis, and borreliosis. He also said it is known to transmit a type of rickettsia in its native environment. But he stressed that in the U.S., the carrying and transmission capabilities of the tick could be different, and it shouldn’t be assumed the tick can transmit anything — more research is needed. Pathogen studies are underway at the U.S. Department of Agriculture, the Centers for Disease Control, and some universities to gain a better understanding of what the tick is or isn’t able to transmit, he said. Whether or not it becomes a vector for disease, its potential as a “major pest of livestock” is already known, he added.

“It’s just a matter of time before it’s abundant in Connecticut,” he said, and added that he “wouldn’t be surprised” if it reached Massachusetts.

“There’s no reason to think it’s going to stop in Connecticut,” Johnson said. “To me it’s not a question of if but when.”

“I think this is primarily going to be a livestock problem, not a people problem,” Barnstable County entomologist Larry Dapsis said. Dapsis is intent on setting up a livestock surveillance and monitoring network on the Cape, where he said alpaca and goats are widespread. He suspects the tick will enter the commonwealth through interstate transportation of livestock, and wants to locate any animals beset by ticks as soon as he can.

“These things can build up into tremendous numbers and bleed animals out,” he said. Animals either die from “significant blood loss” or are weakened, making them more susceptible to disease, he said. As an example of what great multitudes of ticks can do, Dapsis noted one field study in Africa that found a “medium-size” giraffe died due to blood loss from 40,000 ticks. Closer to home, he said his wife, who worked as a veterinary technician, treated a Great Dane covered with 600 engorged dog ticks. The animal was in a “severely anemic” state.

“If we find it on one farm, that’s going to suggest that it’s spreading out rapidly,” he said. Its ability to spread rapidly may be due in part to a reproductive advantage it has. “They don’t need males to mate,” he said. “It’s called parthenogenesis.”

In a nutshell, the female ticks can self-fertilize and lay eggs.

Dapsis said farmers should be vigilant. “If they acquired livestock from Pennsylvania or New Jersey — or even New York — they should give those animals a tick check,” he said. “If the tick is a rusty reddish brown, that’s a big clue.” Asian longhorned ticks look distinctly different from other ticks commonly found in Massachusetts, he said.

Dapsis said thus far the Asian longhorned tick doesn’t hold a candle to a longstanding indiginous menace. Black-legged ticks, i.e., deer ticks, remain “front and center” for tick-oriented public health risks.  

The best method of keeping those or any ticks at bay is careful use of permethrin on clothing and footwear, he said.


Crawling around New York

Asian longhorned ticks are rampant on Staten Island, one of the five boroughs of New York City, according to Columbia University eco-epidemiologist Maria Diuk-Wasser, who studies ticks there. Deer are also numerous there.

“So far we’ve only found [them] on deer,” Diuk-Wasser said. “They’re not on mice, for some reason.”

The City of New York is engaged in a program to reduce deer on Staten Island through a male deer vasectomy program, she said. As the New York Times and several other news outlets have reported, deer car strikes and Lyme disease have both risen in the borough in recent years.

Diuk-Wasser and her colleagues have taken the opportunity to examine deer sedated in the vasectomy process for ticks. Numerous black-legged (deer), lone star, and Asian longhorned ticks were found on these deer. But she has also found Asian longhorned ticks in yards, parks, and even on sidewalks.

University of Rhode Island tick researcher Tom Mather visited Staten Island last summer. He said he and a colleague didn’t have to travel much past a parking lot to capture an abundance of these ticks. “What we found was a shock,” he said.

On their initial drag, they captured numerous Asian longhorned tick larvae. He discovered in short order the tick was quite abundant there. Mather said he’s seen evidence that suggests these ticks may be moving up the I-95 corridor on dogs.

“I think it’s only a matter of time,” he said about their arrival in Rhode Island.

“It is alarming,” Cornell entomologist Jody Gangloff-Kaufmann said of the ticks’ profusion in New York State.

Gangloff-Kauffmann, who is community outreach coordinator for the New York State Integrated Pest Management Program, said her colleagues have collected over 100,000 Asian longhorned ticks in the Hudson Valley.

A key factor as to why these ticks are able to multiply so swiftly, she said, is an absence of males. Not only do they reproduce via parthenogenesis, but all offspring appear to be female, therefore all offspring are capable of breeding more ticks. She said she was unaware of any male Asian longhorned ticks discovered in the U.S. “A single female can start a new infestation in a given area,” she said.

Presently, the tick is found in high concentrations where livestock isn’t abundant but deer are, but she said that could change, and the cash cow for New York livestock is dairy cattle, she said. She pointed to Otsego County, where Chobani Yogurt has brought a boom to the dairy industry. It would be problematic if the ticks beset cattle there, especially organically fed animals.

“It’s a problem for organic dairy because they can’t use an acaricide,” she said. Acaricides are pesticides that kills mites and ticks.

The “host range,” all the types of animals Asian longhorned ticks can be found on, still hasn’t been fathomed, Gangloff-Kauffmann said. But as with what diseases it carries, she thinks scientists are about to turn a corner. “This year I think will be a defining year for a lot of information,” she said. She holds this opinion because of the intense scientific research being dedicated to the tick.

Longtime Tufts tick researcher Sam Telford said he is a bit underwhelmed by the Asian longhorned tick. In New England, he said animal husbandry is so developed, he cannot envision cattle being overrun by these ticks. New England cattle are well groomed and well cared for, he said.

He agreed it’s “only a matter of time” before the tick makes it to Massachusetts, but said research dollars are better spent presently on the black-legged tick, the carrier of Borrelia bungefori, the bacteria behind Lyme, and other diseases, and the lone star tick, which harbors several diseases and can trigger alpha-gal meat allergies. He said the Asian longhorned tick isn’t proven to transit anything.

Michael Skvarla, director of the Insect Identification Laboratory at Pennsylvania State University’s College of Agricultural Sciences, said he was very concerned about the tick.

It’s found in areas around Philadelphia, but “hasn’t made it very far west yet,” he said.

In addition to its sheep and swine, Pennsylvania is a significant producer of beef cattle. “For livestock, it could be a very big deal,” he said.

It doesn’t appear to prefer humans, Diuk-Wasser said, but temper that with the fact that it is known to harbor disease in its native Asia: “The big question right now is, Is this tick going to be a vector for human pathogens in the United States?”

Updated with more details – Ed.