What to watch for with Asian longhorned ticks and Theileria in Ohio in 2024

– Tim McDermott DVM, OSU Extension Educator, Franklin County (originally published in Farm and Dairy)

Visit go.osu.edu/BITE, your guide to ticks, mosquitoes, and other biting pests. Photo: Anna Pasternak, UK entomology graduate student

One of the worrisome things about ticks in Ohio has been the increasing numbers of ticks of medical importance to humans, companion animals, and livestock as we have gone from one tick of medical importance twenty years ago to five now, including two new ticks in the past few years. While ticks have always been a problem in cattle, the invasive Asian longhorned (ALHT) tick that was first discovered in Ohio in 2020 has demonstrated the ability to not only vector, or transmit disease to cattle, but to cause mortality in cattle through high numbers of ticks feeding upon the animals. I first wrote about ALHT  in All About Grazing in July of 2020 with the article “The Threat of Asian longhorned tick continues” and then followed up with a March 2nd, 2023 article “Managing Asian longhorned ticks on pasture” so I want to provide an update on where we are in the state of Ohio with ALHT right now.





Where are we seeing ALHT in Ohio right now? As of the end of 2023, we had positively identified ALHT in 11 counties in Ohio including Franklin, Delaware, Ross, Gallia, Vinton, Jackson, Athens, Morgan, Monroe, Belmont, and Guernsey county. We anticipate finding more positive counties in 2024 as this tick likes to feed on many different species of wildlife and therefore can move on wildlife while they are feeding over a 7–10-day period. To learn more about ALHT check out the BITE SITE link below.

Have we found Theileria in cattle in Ohio? Yes, we have had positive diagnosis through Ohio’s Animal Disease and Diagnostic Laboratory and Virginia’s ViTALs laboratory of Theileria orientalis IKEDA in eight counties including Crawford, Guernsey, Adams, Columbiana, Tuscarawas, Monroe, Belmont, and Harrison counties. Our first case of Theileria in Ohio was found in September of 2022. Theileria can cause increased heart rates and respirator rates, anemia, jaundice, open cows, and increased mortality. There is no approved treatment, except supportive, approved in the US.

When should I start scouting for ALHT? While you can encounter a tick any month of the year in Ohio and we have in fact had positive cases of Lyme disease diagnosed in every month of the year in Ohio, the Asian longhorned ticks is known for preferring a little more heat and humidity than most native Ohio tick species. Having said that, in 2023, we got a detection of ALHT on a farm in Gallia County in April! Our Ohio weather can be pretty variable. The producer reported 80 degrees in the two weeks prior, so the ticks emerged from over wintering to feed. Our largest numbers of ALHT on cattle have been in July, but we know that the weather can play a factor in emergence.

There is a test your veterinarian can use to diagnose Theileria in a suspected case. If you have medical concerns regarding ticks and Theileria in cattle, make sure you have a valid veterinarian-client-patient relationship in place so that you can get the best medical guidance from your vet for keeping your animals tick and tick-borne disease safe.

I have been collaborating with colleagues in the Ohio State College of Food, Agricultural, and Environmental Sciences, the Ohio State College of Veterinary Medicine, and our Knowledge Exchange data hosting group to create a website to host information on biting arthropods and the diseases they can vector over the past year or two. Introducing the BITE SITE at go.osu.edu/BITE. This site will be kept up to date on the newest research and data to assist Ohio producers keep themselves, their families, and their animals tick safe.

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