Invasive Ticks Spread In MD, Threaten Animals


The CDC said Asian longhorn ticks, first reported in the United States in 2017, appear to be less attracted to human skin than well-known native ticks. The pest, pictured above, is spreading in Maryland. (Shutterstock)

Patch manager Deb Belt originally posted this story.

MARYLAND — A winter-hardy species of exotic tick that researchers think killed three otherwise healthy cattle in Ohio, has been found in Maryland and 18 other states.

In addition to Maryland, Asian longhorned ticks have been found in Arkansas, Connecticut, Delaware, Georgia, Indiana, Kentucky, Massachusetts, Missouri, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Virginia and West Virginia, according to the Centers for Disease Control and Prevention.

The Maryland Extension Service said the tick species has likely been in the U.S. since 2013. In March 2023, the Service said it was confirmed in nine states, but that tally has since doubled.

Longhorn ticks are more commonly found in tall grass and pasture environments more so than forest environments, the Maryland Extension Service said. While they prefer to feed on wildlife and livestock, longhorned ticks will feed on pets and humans, as well.

The longhorned ticks have been known to carry infectious parasites and bacteria to both humans and animals. They can transmit bovine theileriosis and babesiosis to livestock. These diseases can lead to decreased milk production in cows and a decrease in wool quantity and quality in sheep, as well as animal death, the Extension Service said.

The CDC said Asian longhorn ticks, first reported in the United States in 2017, appear to be less attracted to human skin than well-known native ticks, such as the blacklegged tick, lone star tick, and the American dog tick. The agency warned, however, that the germs spread by tick bites have made people and animals seriously ill in other countries.

Researchers at Ohio State University concluded that a 2021 infestation of Asian longhorned ticks was behind the deaths of three cattle, including a previously healthy adult bull who died of severe blood loss from tick bites, according to a news release.

The bull was 5 years old and “enormous,” Risa Pesapane, the senior author of the paper published in the Journal of Medical Entomology and an assistant professor of preventive medicine at Ohio State, said in a news release.

“To have been taken down by exsanguination by ticks, you can imagine that was tens of thousands of ticks on one animal,” said Pesapane.

The ticks feed mainly on deer and raccoons but have also been found on dogs and cats, cattle sheep, goats, horses, squirrels, rabbits, skunks, opossums and groundhogs.

The tiny brown ticks are about the size of a sesame seed in some stages and pea size when engorged. Females reproduce asexually and can lay up to 2,000 eggs at a time. Their offspring can do the same.

“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.”

Researchers estimated there were about 1 million longhorned ticks in the pasture of about 25 acres where the cattle that died had been grazing. A pesticide application in 2021 eradicated the ticks, but they returned a year later.

“The good news about the ticks, though, is that most tick control agents that we currently have seemed to kill them,” Pesapane said. “Still, managing them is not easy because of how numerous they are and how easily they can come back.”

Pesticide applications have limits, though. Asian longhorned ticks hide easily in vegetation, and unless the pesticide is applied directly to the insect, they’re likely to survive.

The best recourse is to target them early in the growing season when adults become active again, but before they lay eggs.

“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,” Pesapane said.

She added, “There is no getting rid of them.”

If you think you’ve found an Asian longhorned tick, remove it from the animal or person as soon as possible, the CDC advised. Save the ticks in rubbing alcohol in a jar or resealable bag, and contact your local health department for more guidance.

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