Seroprevalence of equine leptospirosis in Poland (2019-2023).

Background: Leptospirosis in horses is associated with various clinical signs, potentially leading to fatal outcomes. Additionally, the disease may pose a zoonotic risk to individuals involved in handling infected animals. Implementing a serological monitoring programme in the equine population is one of the key tools used to reduce the risk of transmission of Leptospira infections to humans.

Objectives: To provide new insights into the seroprevalence of leptospirosis in domestic horses in Poland.

Study design: Serological monitoring program.

Methods: Data were collected from serological surveys of horse serum samples across 14 of the 16 provinces between 2019 and 2023. A total of 4474 horse serum samples were tested using the microscopic agglutination test (MAT), with 8 Leptospira serovars from 7 European serogroups. Statistical analyses and data visualisation were performed using Python-based libraries. Prevalence was calculated as absolute and relative percentages. Pairwise prevalence comparisons employed chi-squared tests with adjustments for multiple comparisons. Bayesian posterior probabilities were estimated to evaluate prevalence differences between groups.

Results: The 5-year study showed a relatively high exposure (25.1%) of horses to Leptospira antigens in Poland. Dominant Leptospira serogroups were: Sejroe (39.2%), Pomona (14.6%), Bratislava (11.2%), and Grippotyphosa (10.1%). Pomorskie recorded the highest percentage of positive samples (29.2%). Conversely, Lubuskie exhibited the lowest prevalence at 16.2%.

Main limitations: Details on the uses of horses were not available.

Conclusions: This analysis provides valuable data on the circulation of Leptospira serogroups across different regions over time. The high seroprevalence of Leptospira in the Polish horse population underscores the necessity of ongoing monitoring, which will aid in the protection of individual horses, herds, and humans from potential infections.