77 January 2026. Volume 20. Number 1 Farnoosh Farsijani 1 , Hamid Akbari 2* , Abbas Imani Baran 3 , Raziallah Jafari Jozani 2, 4 , Arman Shokri 5 1. Faculty of Veterinary Medicine, University of Tabriz, Tabriz, Iran. 2. Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Tabriz, Tabriz, Iran. 3. Department of Pathobiology, Faculty of Veterinary Medicine, University of Tabriz, Tabriz, Iran. 4. Department of Pathobiology, Infectious Diseases and Public Health, School of Animal and Veterinary Sciences, Faculty of Sciences, Engineering and Technology, The University of Adelaide, Adelaide, Australia. 5. Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran. * Corresponding Author: Hamid Akbari, Associate Professor. Address: Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Tabriz, Tabriz, Iran. Phone: +98 (41)36378743 E-mail: h.akbari@tabrizu.ac.ir Original Article Molecular Study of Babesia caballi and Theileria equi in Horses, in Ardabil Province, Iran Background: Equine piroplasmosis (EP), caused by Babesia caballi and Theileria equi, is a prevalent tick-borne hemoprotozoan disease worldwide. In Iran, the disease is endemic and often manifests in subclinical form. To control the disease by detecting carrier horses, real- time polymerase chain reaction (PCR) is a suitable method. Objectives: We aimed to detect B. caballi and T. equi in horses in Ardabil Province, Iran, using SYBR Green I real-time PCR. Methods: This study was conducted from April to August 2015 in 5 cities (Ardabil, Nir, Namin, Sareyn, and Meshginshahr) in Ardabil Province, Iran. Blood samples were randomly collected from 92 healthy horses, noting their age, gender, and sampling location. Genomic DNA was extracted from each sample and assessed, followed by SYBR green I real-time PCR. Data analysis was conducted using Rotor-Gene Q Series software to calculate the target DNA concentration based on the unknown sample’s cycle threshold (Ct) value. Positive values were defined as exceeding 1 ng/reaction. The relationship between horse infection rate and different age groups (1-5, 6-10, and >10 years), gender, and sampling locations was investigated using a chi-square test through SPSS statistical software. P<0.05 were considered significant. Results: In this study, the frequency of B. caballi-infected horses was 9(9.8%), and that of T. equi-infected horses was 4(4.4%). A significant relationship was observed between the B. caballi infection and the age group of 5-10 years. However, there was no significant relationship between the B. caballi infection and gender or sampling locations. Furthermore, no significant relationship was observed between the T. equi infection and the age groups, gender, and sampling locations of the horses. Conclusion: The infection found in apparently healthy horses suggests endemic EP in this region. Therefore, greater focus is needed on controlling and treating carrier horses. Keywords: Babesia caballi, Piroplasmosis, Real-time polymerase chain reaction (PCR), SYBR green, Theileria equi A B S T R A C T How to Cite This Article Farsijani, F., Akbari, H., Imani Baran, A., Jafari Jozani, R., & Shokri, A. (2026). Molecular Study of Babesia caballi and Theileria equi in Horses, in Ardabil Province, Iran. Iranian Journal of Veterinary Medicine, 20(1), 77-86. http://dx.doi.org/10.32598/ijvm.20.1.1005416 http://dx.doi.org/10.32598/ijvm.20.1.1005416 Use your device to scan and read the article online Article info: Received: 14 Jul 2025 Accepted: 18 Aug 2025 Publish: 01 Jan 2026 Copyright © 2026 The Author(s); This is an open access article distributed under the terms of the Creative Commons Attribution License (CC-By-NC: https://creativecommons.org/licenses/by-nc/4.0/legalcode.en), which permits use, distribution, and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.