The Iowa Department of Agriculture and Land Stewardship has confirmed the state’s first case of Theileria orientalisIkeda—a blood-borne parasite that causes bovine infectious anemia—in a herd located in southeast Iowa. The parasite is transmitted by the invasive Asian longhorned tick (Haemaphysalis longicornis), also newly detected in the state. This dual emergence marks a significant development for livestock producers, especially as summer tick activity escalates.
Theileria primarily infects red and white blood cells in cattle, potentially leading to severe anemia, lethargy, and even death in affected animals. Pregnant cows and young calves are particularly vulnerable. No treatment is currently approved in the U.S., making prevention and early detection critical.
The Asian longhorned tick, a highly invasive species capable of reproducing without a male, has rapidly expanded across the eastern United States since first being detected in 2017. One female can lay up to 2,000 eggs, making tick control essential to limit the spread of the parasite.
Veterinarians and producers are urged to watch for signs of anemia, jaundice, respiratory distress, and reproductive issues. Suspected cases should be reported immediately, and diagnostic testing should be conducted through the Iowa State University Veterinary Diagnostic Lab.
In a related policy update, Iowa’s Brucellosis and Tuberculosis Eradication Fund will end July 1, 2025, eliminating reimbursements for brucellosis vaccinations after that date.
Key Points for Industry Stakeholders:
🦠 Disease Overview:
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Theileria orientalis Ikeda infects cattle’s red/white blood cells, causing anemia and death in severe cases.
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Symptoms resemble anaplasmosis: fever, jaundice, abortions, lethargy, respiratory distress.
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Pregnant heifers and calves most at risk.
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No approved treatment in the U.S.; infected animals may become lifetime carriers.
🧬 Vector: Asian Longhorned Tick (ALHT):
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First confirmed in Iowa; invasive and highly reproductive.
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Active from March to November; thrives when new livestock enter pastures.
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Found on various livestock and wildlife—and occasionally on humans.
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Known to transmit Theileria, anaplasmosis, babesiosis, and other diseases.
🧪 Monitoring and Reporting:
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Suspected cases should be reported to local veterinarians or state animal health officials.
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Testing available through Iowa State University Vet Diagnostic Lab.
🔍 Prevention & Tick Control Strategies:
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Inspect cattle frequently, focusing on ears, tail, legs, and udder folds.
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Use pyrethroid-based pour-ons or backrubbers; ear tags alone are insufficient.
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Avermectin pour-ons may help with high infestations.
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Avoid needle reuse to prevent blood-borne transmission.
🌾 Pasture and Habitat Management:
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Keep grass trimmed and remove brush.
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Apply EPA-approved acaricides to tick-prone areas.
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Restrict cattle from high-risk pastures when possible.
🚫 Public Health Risk:
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Theileria does not infect humans.
💉 Policy Update – Vaccination Fund Ending:
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Brucellosis vaccine reimbursements in Iowa end June 30, 2025.
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Vouchers must be submitted by July 31, 2025, for final reimbursement.
Cattle producers are encouraged to enhance surveillance, adopt robust tick management protocols, and maintain biosecurity measures to protect herd health this season.
