Listeria, a Gram-positive pathogenic bacterium, mainly affects ruminants and humans, causing listeriosis. It is not considered contagious and primarily occurs sporadically in winter and early spring. Clinical signs in ruminants include septicemia in neonates, meningoencephalitis (circling disease), and abortion in adults. Listeria monocytogenes and Listeria ivanovii are identified as pathogens of warm-blooded hosts among the eight known species of Listeria. In this study, a PCR method was used to detect Listeria spp. in 100 cases of bovine aborted samples. ThesesampleswerereferredtotheCenterofExcellenceinRuminantAbortionandNeonatal Mortality at Ferdowsi University of Mashhad, Iran, between 2022 and 2023.The sample was taken by placing the fetus on its left side. An incision was made in the skin and abdominal muscles on the right flank to obtain a liver sample. DNA was extracted from the samples. Initially, all the samples were tested using the Listeria genus-specific PCR primer. Then, the samples in which the presence of Listeria spp. was confirmed, were re-evaluated using specific primers of L. monocytogenes and L. ivanovii. Out of the total of 117 examined samples, 1 (1%) sample was positive in bacterial culture and 1(1%) sample was declared positive in PCR. Listeriosis is a zoonosis disease that causes abortion and subclinical disease in humans. Dairy cattle are usually a reservoir for bacteria. The significance of this study lies in its use of the molecular method (PCR) to analyze the rate of bovine abortion caused by Listeria. This method offers higher accuracy compared to bacterial culture, making the findings more reliable and impactful.

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