May. 19, 2026
Theileriosis, caused by Theileria orientalis Ikeda, is an emerging tick-borne disease of cattle that has been identified in several U.S. states, including Ohio, and is a growing concern for beef and dairy producers. The disease is transmitted primarily by the Asian longhorned tick and can lead to anemia, weakness, decreased production, and, in severe cases, death. Infected cattle may show signs such as pale mucous membranes, lethargy, and reduced weight gain, although some animals can remain asymptomatic carriers.