Theileria in beef cattle

By Josh Winters, Jackson County Agriculture and Natural Resource Extension Educator

A few weeks ago, I attended a program with Dr. Jonh Currin, Virginia Tech Veterinarian Medicine Extension Specialist, as he talked about his experience with the Asian Longhorn Tick and Theileria in beef cattle. Dr. Currin explained that his first experience with the Asian longhorned tick was in 2017, as it was first detected on a sheep in New Jersey. The Asian longhorned tick is a smaller tick that can reproduce by parthenogenesis, or asexual reproduction. This means that only females are required to reproduce and can lay up to 3,000 eggs at a time. In 2020, the first Asian Longhorn Tick was found in Ohio (Gallia County) on a stray dog.

The Asian Longhorn Tick favors swampy, wooded, and taller grass areas. Fields that have these characteristics tend to have the higher probability for establishment where just simply walking through the field could leave someone covered with ticks. Infestations can cause serious problems for our livestock, as their systems can go into shock with the amount of blood loss these ticks can cause in a short amount of time. In some instances, there have been reports of these ticks in such high numbers to kill a full-grown bull. These tics tend to be found in the ears, groin, and vaginal areas of infested animals.

This tick is also impacting  herds through the transfer of Theileria orientalis, a blood protozoan parasite. This disease was first recognized in the United States in 2018. It is still a relatively new disease to the United States with information rapidly changing around the topic. This disease is expected to spread rapidly across the United States with the first case in Ohio being confirmed in 2022.

According to Dr. Currin, “Theileria orientalis Ikeda and the bacterium Anaplasma marginale cause infectious bovine anemia. Both tick-borne organisms are red blood cell parasites that lead to the destruction of the cell, causing anemia in clinically diseased animals. The clinical signs of theileriosis are the same as for anaplasmosis. It is impossible to distinguish between the two diseases based solely on clinical signs, and a laboratory diagnosis is required.”

So should we be worried, yes and no. While there are still some unknowns and no approved drug for treatment, Dr. Currin says, “Only a small number of animals that are infected with Theileria orientalis Ikeda will ever show clinical signs of disease. Cows show clinical signs over a 2-3 week period. After this initial outbreak, there are not often long-term problems.”

The Asian Longhorn tick is providing many challenges for livestock producers. These ticks are hard to control, but there are some insecticides that can work. Currently at the Jackson Agricultural Research Station, they are doing research on whether this tick can survive being baled in hay. This has been an ongoing research project for the past year. If you are interested in learning more, we are presenting the current findings at this year’s Beef and Forage Field Night. To register, call me at 740-688-5029!