Tick-Borne Diseases Continue to Spread in Missouri Cattle

By Blake Jackson

As tick-borne diseases continue to threaten Missouri's cattle industry, the University of Missouri's College of Veterinary Medicine is strengthening efforts to help livestock producers protect herd health.

Through the Veterinary Medical Diagnostic Laboratory (VMDL), researchers are expanding disease surveillance and providing rapid diagnostic testing to monitor the spread of infections across the state.

Bovine anaplasmosis remains Missouri's most common tick-borne disease in cattle. Spread by the American dog tick, the disease destroys red blood cells, leading to anemia, weight loss, reduced productivity, pregnancy loss, and, in severe cases, death.

A 2025 University of Missouri study found that nearly half of the state's cattle had been exposed to the disease.

Researchers are also tracking the spread of bovine theileriosis, an emerging disease transmitted by the invasive Asian longhorned tick. First identified in Missouri in 2021, this tick has expanded into additional counties and poses growing concerns for producers.

Unlike most tick species, the Asian longhorned tick can reproduce without mating, allowing populations to increase rapidly.

The VMDL has seen a significant rise in testing demand. Laboratory data show testing for Theileria orientalis increased from 263 samples in 2024 to 421 in 2025, with positive cases rising from about 34% to 53%. By mid-May 2026, more than 651 samples had been tested, with nearly 65% returning positive results.

Because bovine anaplasmosis and bovine theileriosis produce similar symptoms, including anemia, weakness, and poor weight gain, laboratory testing is essential for an accurate diagnosis.

The VMDL offers PCR testing capable of detecting both diseases from a single blood sample, with results often available by the next business day.

Experts recommend testing cattle before introducing them into existing herds, as infected animals can spread disease before symptoms appear.

Early surveillance, timely diagnosis, and proactive herd management remain the most effective strategies for reducing economic losses and protecting Missouri's livestock industry.

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