Serological and molecular detection and phylogenetic characterization of Taylorella equigenitalis in horses in Iraq.
- 1Zoonoses Research Unit, College of Veterinary Medicine, University of Baghdad, Baghdad, Iraq.
- 2Department of Internal and Preventive Veterinary Medicine, College of Veterinary Medicine, University of Baghdad, Baghdad, Iraq.
- 3Department of Internal and Preventive Veterinary Medicine, College of Veterinary Medicine, University of Wasit, Wasit, Iraq.
Abstract
Background and aim
Contagious equine metritis caused by Taylorella equigenitalis is an important venereal disease of equids that can impair reproductive performance and facilitate transmission through clinically inapparent carriers. Information on T. equigenitalis infection in Iraqi horses remains limited. This study aimed to determine the serological and molecular occurrence of T. equigenitalis in horses in Iraq, evaluate associations with clinical and epidemiological factors, and characterize PCR-positive isolates using sequencing and phylogenetic analysis.Materials and methods
A total of 157 adult horses from Baghdad, Babylon, Nineveh, and Wasit provinces were examined from March to September 2025. Clinical information was recorded, and blood and genital swab samples were collected. Serum samples were examined using a qualitative enzyme-linked immunosorbent assay (ELISA), whereas DNA extracted from genital swabs was subjected to conventional polymerase chain reaction (PCR) targeting the 16S rRNA gene. PCR-positive products were sequenced, submitted to GenBank, and analyzed phylogenetically. Associations between infection status and clinical and epidemiological variables were statistically evaluated.Results
Of the 157 horses, 52 (33.12%) were ELISA-positive and 23 (14.65%) were PCR-positive for T. equigenitalis. Twenty-one (13.38%) horses were positive by both methods, 31 (19.74%) were ELISA-positive/PCR-negative, two (1.27%) were ELISA-negative/PCR-positive, and 103 (65.61%) were negative by both methods. In mares, seropositivity was significantly associated with reproductive disorders, with the highest proportion detected among those with abnormal vaginal discharge (68.42%), whereas PCR positivity was highest among mares with infertility (50%). Seropositivity was higher in horses aged >10 years (62.86%) and females (52.38%), whereas PCR positivity was highest among horses aged >5-6 years (38.1%) and females (25%). Sequencing of 23 PCR-positive isolates generated GenBank accession numbers PZ146151.1-PZ146173.1. The Iraqi isolates showed 97.18%-99.12% sequence identity with an Iranian T. equigenitalis isolate (DQ840456.1).Conclusion
The findings provide serological and molecular evidence of T. equigenitalis infection among horses in Iraq and demonstrate associations with reproductive and epidemiological characteristics. Combined serological and molecular surveillance, routine screening of breeding horses, and higher-resolution molecular studies are warranted to clarify transmission dynamics and strengthen prevention and control strategies.
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BibTeX
@article{hussein2026serological,
title = {{Serological and molecular detection and phylogenetic characterization of Taylorella equigenitalis in horses in Iraq.}},
author = {Zaid Salah Hussein and Amanee Mohammed Radhy and Saba Thamer Mosa and Hasanain A J Gharban},
journal = {Veterinary world},
year = {2026},
month = sep,
doi = {10.14202/vetworld.2026.4244-4258},
url = {https://europepmc.org/article/MED/42928766},
note = {CC BY},
}
RIS
TY - JOUR
TI - Serological and molecular detection and phylogenetic characterization of Taylorella equigenitalis in horses in Iraq.
AU - Zaid Salah Hussein
AU - Amanee Mohammed Radhy
AU - Saba Thamer Mosa
AU - Hasanain A J Gharban
PY - 2026
DA - 2026/09/24
JO - Veterinary world
DO - 10.14202/vetworld.2026.4244-4258
UR - https://europepmc.org/article/MED/42928766
AB - Background and aim Contagious equine metritis caused by Taylorella equigenitalis is an important venereal disease of equids that can impair reproductive performance and facilitate transmission through clinically inapparent carriers. Information on T. equigenitalis infection in Iraqi horses remains limited. This study aimed to determine the serological and molecular occurrence of T. equigenitalis in horses in Iraq, evaluate associations with clinical and epidemiological factors, and characterize PCR-positive isolates using sequencing and phylogenetic analysis.Materials and methods A total of 157 adult horses from Baghdad, Babylon, Nineveh, and Wasit provinces were examined from March to September 2025. Clinical information was recorded, and blood and genital swab samples were collected. Serum samples were examined using a qualitative enzyme-linked immunosorbent assay (ELISA), whereas DNA extracted from genital swabs was subjected to conventional polymerase chain reaction (PCR) targeting the 16S rRNA gene. PCR-positive products were sequenced, submitted to GenBank, and analyzed phylogenetically. Associations between infection status and clinical and epidemiological variables were statistically evaluated.Results Of the 157 horses, 52 (33.12%) were ELISA-positive and 23 (14.65%) were PCR-positive for T. equigenitalis. Twenty-one (13.38%) horses were positive by both methods, 31 (19.74%) were ELISA-positive/PCR-negative, two (1.27%) were ELISA-negative/PCR-positive, and 103 (65.61%) were negative by both methods. In mares, seropositivity was significantly associated with reproductive disorders, with the highest proportion detected among those with abnormal vaginal discharge (68.42%), whereas PCR positivity was highest among mares with infertility (50%). Seropositivity was higher in horses aged >10 years (62.86%) and females (52.38%), whereas PCR positivity was highest among horses aged >5-6 years (38.1%) and females (25%). Sequencing of 23 PCR-positive isolates generated GenBank accession numbers PZ146151.1-PZ146173.1. The Iraqi isolates showed 97.18%-99.12% sequence identity with an Iranian T. equigenitalis isolate (DQ840456.1).Conclusion The findings provide serological and molecular evidence of T. equigenitalis infection among horses in Iraq and demonstrate associations with reproductive and epidemiological characteristics. Combined serological and molecular surveillance, routine screening of breeding horses, and higher-resolution molecular studies are warranted to clarify transmission dynamics and strengthen prevention and control strategies.
SN - 0972-8988
SN - 2231-0916
ER -