By Doug Graves
COLUMBUS, Ohio – An Asian longhorned tick was found on a stray dog in Gallia County in Ohio in 2020. A second such tick was found on a cow in Jackson County in 2021. The next year, a farmer from Monroe County in southeastern Ohio called Ohio State University extension to report that three of his 18 cattle had died and all were heavily infested with these ticks. Blood loss was the cause.
Scientists from Ohio State have reported in the Journal of Medical Entomology on the state’s first known established population of Asian longhorned ticks, and are now conducting research focused on monitoring and managing these pests.
Researchers say the tiny brown ticks (the size of a sesame seed in some life stages and pea-sized when engorged) are persistent. Surveillance showed they returned the following summer to this Monroe County farm despite the application of pesticides in 2021.
Just a handful of the hundred ticks from the farm screened for infectious agents tested positive for pathogens, including Anaplasma phagocytophilium. That pathogen can cause disease in animals and humans. The tick also carries another pathogen – Theileria orientalis – that affects cattle, and cases of bovine theileriosis, that has been reported in Ohio.
“They are going to spread to pretty much every part of Ohio and they are going to be a long-term management problem. There’s no getting rid of them,” said Risa Pesapane, an assistant professor of veterinary preventive medicine at Ohio State. “The good news about the ticks, though, is that most tick control agents that we currently have seem to kill them. Still, managing them is not easy because of how numerous they and are how easily they can come back.”
These ticks tend to favor large livestock and wildlife, such as cattle and deer.
Asian longhorned ticks originate from East Asia and were first detected in the United States in New Jersey in 2017. When Pesapane joined Ohio State in 2019 as a tick-borne disease ecologist, the ticks were reported in West Virginia. Pesapane said it was only a matter of time before they crossed the river into Ohio.
And spread they did. As of April 2023, the longhorned ticks have been found in Ohio, Indiana, Kentucky, Tennessee, Arkansas, Connecticut, Delaware, Georgia, Maryland, Massachusetts, Missouri, New Jersey, New York, North Carolina, Pennsylvania, Rhode Island, South Carolina, Virginia and West Virginia.
The invasion of these Asian longhorned ticks caught the eye of producers everywhere since the report of the recent attack and death of cattle at the farm in southeast Ohio.
“One of those was a healthy male bull, about five years old. Enormous. To have been taken down by exsanguination by ticks, you can imagine that was tens of thousands of ticks on one animal,” Pesapane said.
Pesapane and colleagues collected nearly 10,000 ticks within about 90 minutes of the farm, leading her to speculate that there were more than one million of them in a 25-acre pasture.
According to researchers, the Asian longhorned tick appears to be less attracted to human skin. They know the female tick can lay up to 2,000 eggs at a time and the female can reproduce without mating.
“There are no other ticks in North American that do that,” Pesapane said. “So, they can just march on, with exponential growth, without any limitations or having to find a mate.”
Researchers know that these ticks have already been found on pets, livestock, wildlife and people. They still don’t know, however, if they prefer wooded or open areas. Because of their ability to hide in vegetation, Asian longhorned ticks also can escape pesticides that kill only when coming into direct contact with a pest.
“It would be wisest to target them early in the season when adults become active, before they lay eggs, because then you would limit how many will hatch and reproduce in subsequent years,” Pesapane said. “But for a variety of reasons, I tell people you cannot spray your way out of an Asian longhorned tick infestation. It will require an integrated approach.”
In other countries, it has been discovered that these ticks can make people and animals seriously ill. With ongoing testing of ticks here in the United States, however, there is no certainty that this tick will contribute to the spread of Lyme disease. Another laboratory study, however, found that this tick has the ability to carry and spread the bacteria that causes Rocky Mountain spotted fever.
Pesapane said that tick inspections of livestock could provide a window for application of an antiparasitic agent to eliminate the risk of transporting the exotic arachnids across multiple state lines.
Ohioans are encouraged to help with research efforts. Anyone who thinks they’ve spotted an Asian longhorned tick can email for instructions on how to collect the specimen and send it to Ohio State scientists as part of ongoing surveillance. To date, the lab has received Asian longhorned ticks from residents in 11 of Ohio’s 88 counties.
More information about spotting Asian longhorned ticks and preventing tick exposure is available on Ohio State’s Bite Site (www.kx.osu.edu/bite).