Serological Surveillance of Equine Leptospirosis in Croatia in the Period From 2012 to 2022: A Key Insight Into the Changing Epizootiology.
Authors: Benvin Iva, Perko Vesna Mojčec, Maljković Maja Maurić, Habuš Josipa, Štritof Zrinka, Hađina Suzana, Perharić Matko, Zečević Iva, Cvetnić Marija, Turk Nenad
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Between 2012 and 2022, Croatian veterinary authorities conducted serological surveillance of leptospirosis across 61,724 serum samples from clinically healthy horses using microscopic agglutination testing (MAT), establishing baseline epidemiological data for this re-emerging zoonotic pathogen. Overall seroprevalence reached 10.80%, with considerable annual variation (5.00–15.94%), indicating sustained exposure to Leptospira species across the equine population. Pomona emerged as the dominant serovar in horses (41.98% of positive cases), followed by Grippotyphosa (31.34%), with Pomona showing a concerning year-on-year increase—a finding unprecedented in European equine populations and suggesting potential pathogenic adaptation to equine hosts. The predominance of anamnestic (historical) titres indicates prior infection rather than acute disease, yet the rising prevalence of Pomona warrants investigation into reservoir hosts, environmental persistence and transmission routes to better inform management of both equine and public health risks. These results should prompt farriers and equine practitioners to maintain heightened awareness of leptospirosis as an occupational hazard, particularly where contact with contaminated urine is possible, and to advise clients on biosecurity measures and vaccination protocols where available.
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Practical Takeaways
- •Equine practitioners in Croatia should be aware that approximately 1 in 10 horses may have serological evidence of leptospiral exposure, with serovar Pomona now the dominant circulating strain
- •Implement appropriate biosecurity and occupational health measures given the zoonotic nature of leptospirosis and the high seroprevalence in apparently healthy horses
- •Consider leptospirosis in differential diagnoses for reproductive failure, renal disease, or uveitis in Croatian horses, and monitor for emerging clinical disease patterns as serovar Pomona prevalence increases
Key Findings
- •Overall seroprevalence of equine leptospirosis in Croatia was 10.80% (6,665/61,724 samples) over the 2012-2022 period with annual variation between 5.00% and 15.94%
- •Serovar Pomona was the most prevalent (41.98% of seropositive horses) followed by Grippotyphosa (31.34%), showing increasing prevalence of Pomona annually
- •This is the first European report of such high seropositivity for serovar Pomona in apparently healthy horses, suggesting possible evolutionary adaptation of this pathogenic serovar in equine populations