Asian longhorned tick invasion threatens livestock in Ohio

An invasive tick species known as the Asian longhorned tick has been identified as a growing threat in Ohio, leading to the death of cattle and raising concerns for the potential spread of disease. 

Researchers at The Ohio State University (OSU) have published their alarming findings in the Journal of Medical Entomology, confirming the first known established population of this pest within the state.

In 2021, the presence of these ticks reached a critical point on a southeastern Ohio farm, where a staggering number of the ticks were blamed for the deaths of three cattle. The farm incident involved tens of thousands of ticks overwhelming the animals, leading to a severe loss of blood.

Exponential growth potential 

Study senior author Risa Pesapane is a tick-borne disease ecologist and an assistant professor of Veterinary Preventive Medicine at Ohio State. She highlighted the tick’s exponential growth potential and the difficulties in managing such infestations due to their sheer numbers and resilience.

“They are going to spread to pretty much every part of Ohio and they are going to be a long-term management problem. There is no getting rid of them,” said Professor Pesapane.

“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 are and how easily they can come back.”

Prolific breeders

The Asian longhorned tick (ALT) is a prolific breeder, capable of asexual reproduction, which allows a single female to lay up to 2,000 eggs without mating. This unique characteristic has facilitated the rapid expansion of their population. 

“There are no other ticks in North America that do that. So they can just march on, with exponential growth, without any limitation of having to find a mate,” Pesapane said. “Where the habitat is ideal, and anecdotally it seems that unmowed pastures are an ideal location, there’s little stopping them from generating these huge numbers.”

Persistent threat

Despite comprehensive control efforts, including the application of pesticides in 2021, these ticks have demonstrated a concerning ability to return and persist in the environment. 

“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. 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,” said Professor Pesapane.

Ohio State researchers are now focused on developing strategies for monitoring and controlling the tick population, emphasizing that conventional pesticide use alone is not sufficient to combat the infestation.

Ohio invasion

This species is originally from East Asia and was first reported in the United States in New Jersey in 2017. When Professor Pesapane joined Ohio State in 2019, the ticks were reported in West Virginia – meaning it was only a matter of time before they crossed the river into Ohio, she said.

Professor Pesapane found the first of these ticks on a stray dog in Gallia County, Ohio in 2020, and another was collected from a cow in Jackson County in June 2021. 

Later that summer, a farmer in Monroe County called Ohio State to report that three of his 18 cattle had died and were heavily infested with ticks.

“One of those was a healthy male bull, about 5 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,” said Pesapane.

Infested pasture 

Within less than two hours on the farm, Pesapane and her team collected almost 10,000 ticks on the Monroe County farm. She speculates that there were more than a million of the ticks across the 25-acre farm. 

“In mid-summer 2021, we collected ALTs from an infested pasture in response to an alert that grazing cattle had been infested with ticks, and 3 of them had died. No ALTs were reported following pesticide treatment of the pasture in fall 2021,” wrote the study authors.

“In the laboratory, we identified 9,287 ticks to species, representing all 3 life stages, as ALTs and tested 100 of the adult females for infectious agents relevant to human and animal health, including Theileria orientalis, a cattle disease agent. Eight field-collected ticks were positive for Anaplasma phagocytophilum (n = 100, 8%); no other infectious agents were detected.”

“Active environmental surveillance showed the return of ALTs in June 2022 despite the tick control efforts in 2021. As ALTs continue to expand their range in the United States, active and passive surveillance studies will be needed to characterize their evolving role in human and animal health.”

Health implications 

The health implications are significant since the ticks have tested positive for pathogens that can affect both animals and humans. In Ohio, cases of bovine theileriosis, a disease affecting cattle, have been reported, raising the stakes for both the agriculture industry and public health officials.

Research efforts

To better understand and manage this invasive species, OSU researchers are calling on Ohio residents to assist in their research efforts by sending any ticks they find to the university. 

For instructions on how to collect the specimen and send it to Ohio State scientists, the email address is ticks@osu.edu. So far, the lab has received Asian longhorned ticks from residents of 11 Ohio counties.

The goal is to create a comprehensive approach that includes early-season targeting of adult ticks, integrated pest management strategies, and policy recommendations for the agriculture industry, such as tick inspections and the application of antiparasitic agents to livestock.

As the Asian longhorned tick continues its spread across Ohio, there is a concerted effort to contain its impact on the state’s livestock and wildlife while safeguarding human health from the potential transmission of tick-borne diseases.

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