First molecular phylogenetic and serological insights into Listeria monocytogenes infection in aborted ewes in Iraq: A cross-border comparative analysis

Vet World Vol.18 July-2025 Article - 11

Research Article

Veterinary World, 18(7): 1899-1910

https://doi.org/10.14202/vetworld.2025.1899-1910

Luma F. M. Al-Ethafa¹

, Ahmed Jassim Almialy²

, Hasanain A. J. Gharban³

, Isra’a M. Essa⁴

, and Sattar R. S. Al-Eqabi⁵

1. Department of Environmental Health, College of Environmental Sciences, Al-Qasim Green University, Babylon 51013, Iraq.

2. Department of Veterinary Clinical Sciences, Faculty of Veterinary Medicine, University of Kufa, Najaf 54001, Iraq.

3. Department of Internal and Preventive Veterinary Medicine, College of Veterinary Medicine, University of Wasit, Wasit 52001, Iraq.

4. Department of Public Health, College of Veterinary Medicine, University of Basrah, Basra, Iraq.

5. Department of Veterinary Public Health, Veterinary Medicine College, University of Wasit, Wasit 52001, Iraq.

Background and Aim: Listeria monocytogenes is a significant zoonotic pathogen linked to reproductive losses in livestock and serious health risks in humans. In Iraq, listeriosis remains underreported in sheep, with limited data on its molecular and epidemiological characteristics. This study aimed to (1) estimate the seroprevalence of L. monocytogenes in recently aborted ewes, (2) evaluate the association between seropositivity and clinical indicators, and (3) perform molecular detection and phylogenetic analysis of polymerase chain reaction (PCR)-confirmed isolates.

Materials and Methods: From November 2023 to August 2024, 168 aborted ewes in Wasit Province, Iraq, were sampled for vaginal swabs and blood. Enzyme-linked immunosorbent assay (ELISA) was used for serological screening, while DNA extracted from swabs underwent PCR amplification targeting the 16S ribosomal RNA gene. PCR-positive samples were sequenced and phylogenetically analyzed using MEGA-11 software. Clinical data were statistically correlated with seropositivity using odds ratios (OR) and relative risk (RR).

Results: ELISA revealed a seroprevalence of 23.21%, with the majority of infections classified as mild. PCR confirmed L. monocytogenes in 3.57% of swabs. Seropositivity significantly correlated with vaginal discharge (30.08%, p = 0.0121), retained placenta, and recent abortion history. Higher infection risk was observed in ewes with no or single previous abortions (OR = 2.464; RR = 2.207) and in flocks with ≤10% abortion rates (OR = 3.729; RR = 2.731). Phylogenetic analysis of six local isolates (GenBank IDs PQ865989.1–PQ865994.1) revealed 96.43%–97.62% sequence identity with an Iranian reference strain (MT071644.1), suggesting regional transmission links.

Conclusion: This study is the first to molecularly characterize ovine L. monocytogenes in Iraq, revealing both the prevalence of subclinical infection and cross-border phylogenetic relationships. The integration of serological and molecular diagnostics highlighted underrecognized infections and provided novel insights into the epidemiology of strains. Findings emphasize the need for broader regional surveillance, improved diagnostic protocols, and biosecurity measures in ovine reproductive health management.

Keywords: ovine abortion, Listeria monocytogenes, enzyme-linked immunosorbent assay, polymerase chain reaction, phylogenetic analysis, Iraq, Iran, 16S ribosomal RNA.

How to cite this article: Al-Ethafa LFM, Almialy AJ, Gharban HAJ, Essa IM, and Al-Eqabi SRS (2025) First molecular phylogenetic and serological insights into Listeria monocytogenes infection in aborted ewes in Iraq: A cross-border comparative analysis, Veterinary World, 18(7): 1899-1910.

Received: 26-02-2025 Accepted: 11-06-2025 Published online: 17-07-2025

Corresponding author: Hasanain A. J. Gharban E-mail: hghirban@uowasit.edu.iq

DOI: 10.14202/vetworld.2025.1899-1910

Copyright: Al-Ethafa, et al. This article is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http:// creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.