University of Tehran Iranian Journal of Veterinary Medicine 2251-8894 20 2 2026 03 01 Isolation and Molecular Identification of the Enterotoxigenic Pathotype of Escherchia coli From Calf Diarrhea in Some Part of Iran 243 250 101889 10.32598/ijvm.20.2.1005630 EN Mahmoud Khormali Department of Microbiology and Immunology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran. Taghi Zahraei Salehi Department of Microbiology and Immunology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran. 0000-0002-5665-5757 Bahar Nayeri Fasaei Department of Microbiology and Immunology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran. Gholamreza Nikbakht Brujeni Department of Microbiology and Immunology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran. Ramak Yahyaraeyat Department of Microbiology and Immunology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran. Samad Lotfollah Zadeh Department of Internal Medicine, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran. Journal Article 2024 08 26 <strong>Background</strong>: Calf diarrhea is a common cause of pre-weaning morbidity and mortality in cattle within livestock operations. <br /><strong>Objectives</strong>: The primary aims of our study were to determine the prevalence and occurrence rate of genes that encode virulence factors (virotypes) in Escherichia coli strains isolated from calves with diarrhea. <br /><strong>Methods</strong>: Rectal swabs were collected from 156 calves exhibiting diarrhea, representing 12 distinct dairy farms located across five provinces in Iran. Through polymerase chain reaction (PCR) analysis, the E. coli isolates were evaluated for the presence of various virulence genes, including f4, f5, f6, f41, f17, cfa/1, sta, and lt. <br /><strong>Results</strong>: Approximately 78.84% of isolates were found to be positive for at least one of the virulence genes. The highest frequency, at 76.28%, was related to the sta virotype. Most isolates analyzed had a single gene, and no combination of fimbrial and enterotoxin genes was found to be predominant. <br /><strong>Conclusion</strong>: These findings underscore the importance of monitoring and understanding the epidemiology of enterotoxigenic E. coli pathotypes to develop effective strategies for managing calf diarrhea and mitigating associated economic losses in the Iranian cattle industry.  https://ijvm.ut.ac.ir/article_101889_397bb9be506b5472f38656d8516257a3.pdf