Asian longhorned ticks are drawing fresh concern from Kansas livestock researchers as cases of the parasite-driven disease bovine theileriosis appear to move westward in 2026. Kansas State University livestock entomologist Cassandra Olds warns that producers need to monitor herds closely because there is No cure or vaccine for the pathogen. Infected cattle can show anemia, fever, jaundice and, in severe instances, death, making early detection important for herd health and productivity.
Olds stresses that infected animals can become lifelong carriers and that symptoms often reappear during stressful events such as transport or late gestation. Pregnant heifers and young calves face heightened risk for serious illness. The potential for subclinical carriers complicates control efforts because animals may look healthy while carrying the parasite.
Transmission pathways extend beyond tick bites, Olds says, noting that the pathogen can move through shared needles and biting flies in addition to ticks. Federal and state animal health officials are tracking the spread, and producers should assume multiple routes can seed infection within herd operations. Spreads westward from its East Coast prevalence, according to USDA’s Animal and Plant Health Inspection Service guidance.
How it spreads
Managing tick populations is one of the few practical defense strategies available because direct medical treatments are limited. Olds recommends routine herd checks, strict biosecurity around injections and equipment, and keeping close records of animal movements between pastures and feedlots. Producers should also be aware that stress events — shipping, calving and nutritional gaps — can trigger clinical episodes in carrier animals.
Researchers at Kansas State point to pasture management tools that can reduce tick pressure. Controlled spring burns are cited in K-State studies as an effective way to lower tick numbers on rangeland, and targeted vegetation management can reduce tick habitat around watering points and fence lines. Integrating such practices with standard herd biosecurity gives producers the best chance to limit exposure. Burning reduces ticks is the central finding K-State researchers highlight from recent field work.
Prevention and management
Federal monitoring through APHIS continues, with most reported activity concentrated along the East Coast but occurrences increasingly documented farther west. Producers who find ticks on livestock, or who observe signs consistent with theileriosis, should contact their veterinarian or state animal health office for testing and guidance. Vigilant record-keeping, avoiding shared needles, and using pasture management practices recommended by extension specialists are immediate steps producers can implement to reduce risk.
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