Missouri cattle producers warned of theileria orientalis

By Blake Jackson

University of Missouri Extension warns cattle producers about Theileria orientalis (ikeda), a recently discovered disease affecting cattle's red blood cells. This parasite, transmitted by ticks and potentially other insects, can cause anemia and impact herd health.

First detected in the US in 2017, Theileria orientalis has reached Missouri with six confirmed counties: Bates, Howell, Oregon, Platte, Shelby, and Webster. While most infected cattle show no symptoms, some may exhibit fever, weakness, and pale gums. Severe cases can lead to jaundice, abortions, and death (usually less than 5%).

Theileria orientalis can be confused with anaplasmosis, another tick-borne disease. A key difference is that anaplasmosis typically affects cattle over 2 years old, while Theileria orientalis can strike both calves and adults.

Transmission and Prevention:

• Asian Longhorned Tick: The primary culprit, this invasive tick transmits the parasite through blood feeding.
• Other Insects: Lice, biting flies, and even other tick species might play a role.
• Contaminated Equipment: Sharing needles, dehorning tools, or castration equipment between infected and healthy animals can spread disease.
• Newborn Calves: Up to 10% of calves born to infected mothers can carry the organism.

Unfortunately, there's no current vaccine for Theileria orientalis. Producers should focus on preventing tick infestations. Here are some recommendations:

• Tick Management: Refer to the Virginia Cooperative Extension's online guide (https://www.pubs.ext.vt.edu/tags.resource.html/pubs_ext_vt_edu:beef-cattle) for effective tick control practices.
• Quarantine and Treatment: New animals should be quarantined and treated for ticks before introduction to the herd.
• Hygiene Practices: Regularly disinfecting equipment that might come in contact with blood and changing needles between animals are crucial steps to prevent transmission.

While antibiotics used for anaplasmosis are ineffective against Theileria orientalis, minimizing stress and providing supportive care can help infected animals recover. By implementing these preventive measures, producers can safeguard their herds from this emerging threat.

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