• Bom Harris, DVM

New Tick Brings New Disease to Virginia



The Longhorn tick was first identified in Virginia in 2017. Unfortunately, it has brought with it a challenging new disease affecting cattle in multiple states. Theileria is a tick-borne parasite that disrupts red blood cells. It can cause a variety of symptoms, which makes it difficult to diagnose without blood testing.


The symptoms most commonly reported include anemia, sudden death, weakness, respiratory distress, abortion (possibly widespread), and chronic ill thrift. Any combination of these symptoms can be seen and the disease can look similar to anaplasmosis. Theileria is primarily spread by ticks, but can also be spread through multi-use needles.


The best way to protect your herd is to use appropriate measures for fly and tick control and use individual needles when treating or vaccinating animals. Consider using a pour-on insecticide on arrival when adding animals to your herd. As we enter tick season, keep these disease symptoms in mind and contact your veterinarian if you have concerns. The disease can be diagnosed through a blood test currently conducted at Virginia Tech.


Due to the risk of significant economic losses associated with this disease, it is important for producers to be vigilant and stay up to date on the progress of this disease.

© Old Dominion Veterinary Services.

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