Tehran University of Medical Sciences Iranian Journal of Parasitology 1735-7020 11 1 2016 03 14 86 90 Gholamreza HABIBI Dept. of Parasite Vaccine Research and Production of Razi Vaccine and Serum Research Institute, Karaj, Iran Kasra ESMAEILNIA Dept. of Parasite Vaccine Research and Production of Razi Vaccine and Serum Research Institute, Karaj, Iran Mohammad Hasan HABLOLVARID Dept. of Pathology of Razi Vaccine and Serum Research Institute, Karaj, Iran Asghar AFSHARI Dept. of Parasite Vaccine Research and Production of Razi Vaccine and Serum Research Institute, Karaj, Iran Mohsen ZAMEN Dept. of Immunization of Razi Vaccine and Serum Research Institute, Karaj, Iran Soghra BOZORGI Dept. of Parasite Vaccine Research and Production of Razi Vaccine and Serum Research Institute, Karaj, Iran 2016 03 14 2016 03 14 Background: Equine piroplasmosis (EP) is the cause of persistent tick-borne infection with no symptoms, but the most important problem of EP is due to the persistent carrier state. Carrier animals to Babesia (Theileria) equi (Laveran 1901) and B. caballi (Nuttall, 1910) infestation could be identified by extremely sensitive PCR-based method. The purpose of this study was to identify the causative agents of equine piroplasmosis based on molecular and microscopic assays in equids from Kurdistan Province, Iran. Methods: Thirty one horse and mule blood samples were used with history of liv­ing in Kurdistan Province of Iran.  The blood specimens were utilized for T. equi and B. caballi DNA identification by PCR and Giemsa stained smears for micro­scopic observation. Results: The results clearly showed the presence of B. (Theileria) equi DNA in 30 of 31 blood samples (96.77%), but the microscopic examination revealed the 3 of 31 positive Babesia like organisms in the red blood cells (9.67%).  Conclusion: The obtained results demonstrated the presence of hidden B. (Theil­eria) equi infection in horses with previous habitance in Kurdistan Province of Iran. The carrier animals became a main source of infection and can transmit the disease. Therefore, hidden infection might be considered as a health threatening and limit­ing factor in animals used in therapeutic antisera research and production centers. https://ijpa.tums.ac.ir/index.php/ijpa/article/view/814 https://ijpa.tums.ac.ir/index.php/ijpa/article/download/814/657