CASE REPORT article
Front. Vet. Sci.
Sec. Parasitology
Retrospective discovery of Theileria orientalis Ikeda in Haemaphysalis longicornis Neumann ticks on a cow-calf farm in Tennessee (US)
Provisionally accepted
R. A. Butler1,2*
Lisa Muller3
Karen C. Poh4
M. Aguilar4K. S. Hokkanen-Harmon5J. G. Chandler6D. Grove3
R. T. Trout Fryxell6- 1US Centers for Disease Control and Prevention Research Centers, Atlanta, United States
- 2Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, Knoxville, United States
- 3School of Natural Resources, University of Tennessee, Knoxville, Knoxville, United States
- 4United States Department of Agriculture, Pullman, United States
- 5University of Tennessee, College of Veterinary Medicine, Knoxville, United States
- 6University of Tennessee, Department of Entomology and Plant Pathology, Knoxville, United States
Select one of your emails
You have multiple emails registered with Frontiers:
Notify me on publication
Please enter your email address:
If you already have an account, please login
You don't have a Frontiers account ? You can register here
ABSTRACT Theileria orientalis Ikeda is a protozoan parasite that was recently detected in Haemaphysalis longicornis Neumann ticks and bovine serum samples in the United States (US). This parasite is known to cause theileriosis in bovine hosts and has negatively impacted cattle industries internationally. The transmission of this pathogen at the livestock-wildlife interface in the US is not fully understood. Theileria orientalis Ikeda was reported by producers on a cow-calf farm in eastern Tennessee. Retrospective analysis of field-and host-collected H. longicornis resulted in the detection of T. orientalis Ikeda in nymphal H. longicornis ticks collected from cattle (Bos taurus), domestic cat (Felis catus), raccoon (Procyon lotor), and Virginia opossum (Didelphis virginiana); notably, the protozoan DNA was not amplified from the blood of these hosts. Multiple hosts (cattle, raccoon, Virginia opossum, and a domestic cat) were responsible for supporting T. orientalis Ikeda infected H. longicornis ticks on the farm. Targeting these hosts with acaricidal treatments could be important for reducing tick abundance and pathogen transmission. Additionally, biosecurity practices such as glove and syringe and needle changes between handling of bovine hosts are important for preventing accidental mechanical transmission of Theileria parasites.
Keywords: Cattle, Haemaphysalis longicornis Neumann, Theileria orientalis Ikeda, tick, Vector-borne disease, wildlife
Received: 17 Dec 2025; Accepted: 10 Feb 2026.
Copyright: © 2026 Butler, Muller, Poh, Aguilar, Hokkanen-Harmon, Chandler, Grove and Trout Fryxell. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: R. A. Butler
Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.