University of Missouri Director of Veterinary Extension Craig Payne urges cattle producers to watch for signs of disease associated with Theileria orientalis (ikeda), a protozoal organism recently detected in Missouri.
This organism, which primarily affects cattle, infects red blood cells. The immune system attacks the infected cells, resulting in anemia. The disease is primarily spread by the invasive Asian longhorned tick.
It was first diagnosed in a cow-calf herd in Virginia in 2017. The first Missouri case was detected in Howell County in June 2023. Payne says that by the end of June 2024, there were 10 counties in Missouri where cattle tested positive. As of Oct. 1, 2025, that number is up to 48.
Payne notes the Missouri Department of Agriculture has an updated map showing the counties where the disease has been confirmed.
Source : missouri.edu