Leptospiral infection in domestic mares in North Queensland

Leptospira species are found worldwide, favouring tropical regions, and infect a wide range of animal species. Although renal persistence in infected individuals and excretion in urine is thought to be the primary mechanism of disease transmission, recent reports have suggested that persistence in the reproductive tract may be a feature in certain species, including the horse. The aim of this study was to investigate leptospiral infection, particularly within the reproductive tract, in healthy, non-breeding mares. Serum and endometrial swab samples were collected from 50 mares from the James Cook University Teaching Animal Herd, as well as, where possible, free-catch urine (n = 19). Sera were screened for antibodies to 24 Leptospira serovars, using the microscopic agglutination test (MAT). Endometrial and urine samples underwent real-time PCR testing, targeting the leptospiral rrs gene. Overall, the seroprevalence of leptospirosis was 48% (95% CI: 34%-62%), with serovars Arborea, Bratislava and Australis detected most frequently. PCR positive results were obtained from 1 of 50 (2%) endometrial swabs and 2 of 19 (11%) urine samples. This is the first report of serovar Bratislava in horses in Australia.