Student Case Presentation
Two Cases of Clinical Theileriosis in Calves
| Date/Time: |
9/11/2025 #2
|
| Presenter: |
Helena Trevor |
| Veterinary School: |
VA |
Abstract:
Theileriosis is an emerging foreign animal disease in United States. Present already in several Eastern and Central US states, Theileria orientalis has spread rapidly with the recent introduction of the invasive Asian Longhorn Tick, resulting in a largely subclinical seroprevalence in Virginia cattle with potential economic implications. In rare clinical cases of the disease, an immune-mediated hemolytic anemia is induced, resulting in a progressive chronic anemia and death if left untreated. Most cattle are infected indefinitely, as treatments such as antibiotics and supportive care have historically resolved symptoms but failed to eliminate the hemoparasite. In this report, two separate cases of mixed-breed beef calves originating from farms in Southwest Virginia presented with a history of general listlessness. Clinical signs included elevated vital signs and severe anemia. Theileriosis was diagnosed in clinic using PCR testing and blood transfusions were administered to correct the anemia. Treatment was successful as both calves made a full recovery. This case implicates the potential for blood transfusions - an area of historically limited research in ruminants - as a promising therapeutic option for treatment of Clinical Theileriosis.
