Asian longhorned ticks and Theileria in 2024

By Tim McDermott, Ohio State University Extension Educator ANR, Franklin County

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 20 years ago to five now, including two new ticks in the past few years. While ticks have always been a problem in livestock, 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. As of the end of 2023, we had positively identified ALHT in Franklin, Delaware, Ross, Gallia, Vinton, Jackson, Athens, Morgan, Monroe, Belmont, and Guernsey counties.

Have we found Theileria in cattle in Ohio?
Theileria orientalis is a tickborne protozoon that infects red and white blood cells. We have had positive diagnosis in eight counties including Crawford, Guernsey, Adams, Columbiana, Tuscarawas, Monroe, Belmont, and Harrison. 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 females, 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 lonhorned tick 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. 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 your livestock, 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.

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