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A species of foreign tick came in Ohio in such large numbers in 2021 that their feeding frenzy on a southeastern farm killed three cattle due to significant blood loss, according to researchers.
The Ohio State University experts published a study in the Journal of Medical Entomology on the state's first known established population of Asian long-horned ticks, and they are now undertaking research on monitoring and managing these pests. So far, these ticks are not considered dangerous to human health. They prefer huge animals and wildlife like cattle and deer. Only a few of the hundred ticks checked for infectious agents from the farm tested positive for pathogens, including one that can cause sickness in animals and humans, Anaplasma phagocytophilium. This tick also carries Theileria orientalis, a pathogen that affects cattle, and cases of bovine theileriosis have been observed in Ohio. Researchers believed that the small brown ticks, which are the size of a sesame seed in some stages and pea-sized when engorged, are persistent: surveillance indicated they returned to the farm the following summer despite pesticide application in 2021. "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 Risa Pesapane, senior author of the paper and 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 are and how easily they can come back." Asian long-horned 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 - meaning it was only a matter of time before they crossed the river into Ohio, she said. She found the first of these ticks in Ohio, on a stray dog in Gallia County in 2020, and another was collected from a cow in Jackson County in June 2021. And then a farmer from Monroe County called Ohio State later that summer to report three of his 18 cattle, heavily infested with ticks, had died. "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, who also has a faculty appointment in Ohio State's School of Environment and Natural Resources. Pesapane and colleagues collected almost 10,000 ticks within about 90 minutes on the farm, leading her to speculate that there were more than 1 million of them in the roughly 25-acre pasture. Asian long-horned ticks' secret colonization weapon is the ability to reproduce asexually, with each female laying up to 2,000 eggs at a time - and all 2,000 of those female offspring are able to 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." Because of their ability to hide in vegetation, Asian long-horned 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. But for a variety of reasons, I tell people you cannot spray your way out of an Asian long-horned tick infestation - it will require an integrated approach," Pesapane said. (ANI)
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