Abstract: Leptospirosis is one of the most common zoonotic infections and a major problem in terms of both veterinary medicine and public health. However, the disease is under-recognised and under-diagnosed worldwide, particularly in horses. Clinical leptospirosis in horses is mainly associated with recurrent uveitis (ERU), which has recently been studied more intensively, and reproductive disorders, the epidemiology of which is still relatively poorly understood. To enhance our comprehension of abortions caused by leptospirosis in horses and to identify the causative strains, a serological study was carried out with subsequent molecular characterisation of the isolate obtained. Using the microscopic agglutination test (MAT), serum samples from mares that aborted and foetal fluids (when available) were tested for antibodies against spp. Furthermore, bacteria isolation from kidney cultures was conducted. Of 97 mare serum samples, 21 (21.64%) tested positive, with Grippotyphosa and Pomona being the most frequently detected serogroups. A significantly higher seroprevalence was found in aborting mares compared to the healthy horse population from the same geographical area, as well as a pronounced seasonal variation. Leptospiral antibodies were not detected in any of the foetal fluids, but isolation was successful in 1 case out of 39 (2.56%). Genotyping by multilocus sequence typing (MLST) and core genome multilocus sequence typing (cgMLST) identified the obtained isolate as , serogroup Pomona, serovar Mozdok. Further surveillance and molecular typing of strains causing abortion in horses would be invaluable in understanding the prevalence and impact of leptospirosis on equine reproductive health in Europe.
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Overview
This study investigates the link between exposure to Leptospira bacteria and abortion in mares (female horses) in Croatia.
It aims to better understand how leptospirosis affects horse pregnancies and to identify the specific strains involved.
Background on Leptospirosis and Its Relevance in Horses
Leptospirosis is a widespread zoonotic disease, meaning it can be transmitted between animals and humans.
It poses significant challenges in veterinary medicine and public health worldwide.
In horses, leptospirosis is often underdiagnosed and under-recognized despite its potential impact.
Clinical leptospirosis in horses is mainly known for causing equine recurrent uveitis (ERU), an eye disease, but it can also cause reproductive problems such as abortion.
The epidemiology (distribution and patterns) of leptospiral reproductive disorders in horses remains poorly understood, especially in Europe.
Study Objectives
To clarify the association between leptospiral infection and abortion in mares in Croatia.
To identify which Leptospira serogroups and strains are involved in causing abortions.
Methodology
Serological testing: using the microscopic agglutination test (MAT) to detect antibodies against Leptospira in serum samples from mares that had aborted.
Testing of foetal fluids (when available) for presence of antibodies to Leptospira.
Attempt to isolate Leptospira bacteria from kidney cultures of aborted fetuses.
Molecular characterization: genetic typing of any isolated bacteria using multilocus sequence typing (MLST) and core genome MLST (cgMLST) to determine precise strain identity.
Key Results
Out of 97 serum samples from aborting mares, 21 (approximately 21.6%) tested positive for Leptospira antibodies.
Serogroups Grippotyphosa and Pomona were the most commonly detected, indicating these types of Leptospira were more frequent in aborting mares.
Abortive mares had a significantly higher seroprevalence compared to healthy horses from the same area, suggesting a strong association between Leptospira exposure and abortion.
There was a notable seasonal variation in seroprevalence, implying that risk of infection may fluctuate at different times of the year.
No leptospiral antibodies were found in any foetal fluids tested.
Leptospira bacteria were successfully isolated in 1 out of 39 cases (2.56%), indicating direct bacterial involvement in at least some abortion cases.
The isolated Leptospira strain was identified as belonging to serogroup Pomona, serovar Mozdok, confirming its role in causing abortion.
Significance and Implications
This study provides evidence linking Leptospira infection, particularly serogroups Grippotyphosa and Pomona, with abortion in mares in Croatia.
Identification of the Pomona serovar Mozdok supports the presence of specific pathogenic strains circulating in the region and causing reproductive failure.
The significantly higher antibody prevalence in aborting mares versus healthy horses highlights leptospirosis as an important factor in equine reproductive health.
Seasonal trends may help inform risk management and timing of preventive measures.
Only one bacterial isolate was recovered, underscoring the difficulty of culturing Leptospira but also the value of molecular typing in understanding strain distribution.
Further monitoring and molecular studies are recommended for better epidemiological insight and improved control of leptospirosis in horses across Europe.
Cite This Article
APA
Zečević I, Picardeau M, Vince S, Hađina S, Perharić M, Štritof Z, Stevanović V, Benvin I, Turk N, Lohman Janković I, Habuš J.
(2024).
Association between Exposure to Leptospira spp. and Abortion in Mares in Croatia.
Microorganisms, 12(6), 1039.
https://doi.org/10.3390/microorganisms12061039
Department of Microbiology and Infectious Diseases with Clinic, Faculty of Veterinary Medicine, University of Zagreb, 10000 Zagreb, Croatia.
Picardeau, Mathieu
Biology of Spirochetes Unit, National Reference Center for Leptospirosis, Institut Pasteur, 75015 Paris, France.
Vince, Silvijo
Reproduction and Obstetrics Clinic, Faculty of Veterinary Medicine, University of Zagreb, 10000 Zagreb, Croatia.
Hađina, Suzana
Department of Microbiology and Infectious Diseases with Clinic, Faculty of Veterinary Medicine, University of Zagreb, 10000 Zagreb, Croatia.
Perharić, Matko
Department of Microbiology and Infectious Diseases with Clinic, Faculty of Veterinary Medicine, University of Zagreb, 10000 Zagreb, Croatia.
Štritof, Zrinka
Department of Microbiology and Infectious Diseases with Clinic, Faculty of Veterinary Medicine, University of Zagreb, 10000 Zagreb, Croatia.
Stevanović, Vladimir
Department of Microbiology and Infectious Diseases with Clinic, Faculty of Veterinary Medicine, University of Zagreb, 10000 Zagreb, Croatia.
Benvin, Iva
Department of Microbiology and Infectious Diseases with Clinic, Faculty of Veterinary Medicine, University of Zagreb, 10000 Zagreb, Croatia.
Turk, Nenad
Department of Microbiology and Infectious Diseases with Clinic, Faculty of Veterinary Medicine, University of Zagreb, 10000 Zagreb, Croatia.
Lohman Janković, Ivana
Ministry of Agriculture, Veterinary and Food Safety Directorate, 10000 Zagreb, Croatia.
Habuš, Josipa
Department of Microbiology and Infectious Diseases with Clinic, Faculty of Veterinary Medicine, University of Zagreb, 10000 Zagreb, Croatia.
Conflict of Interest Statement
The authors declare no conflict of interest.
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