Seroprevalence of Leptospira spp. in Working Horses Located in the Central Region of Chile

Urban working horses live in close contact with their owners. They are usually kept in periurban areas of big cities and cohabit with other animals under precarious sanitary conditions, whereas army horses are kept under controlled management and work. These characteristics leave urban working horses in higher risk of exposure to Leptospira spp. and could become a zoonotic risk for their owners. The aim of this study was to determine the frequency of seropositive working horses to diverse serovars of Leptospira spp. and compare them to a group of army horses. The microscopic agglutination test was used to assess the serum of 426 horses (160 working horses and 266 army horses) against two serovars of Leptospira borgpetersenii (Hardjo and Ballum) and four of Leptospira interrogans (Pomona, Canicola, Icterohaemorrhagiae, and Autumnalis). In the urban working horses group, 30.63% of horses were positive to at least one serovar at titers above 1:100, whereas 23.31% of the army horses were positive. The most frequent serovar in the working horse group was Ballum followed by Canicola, whereas in the army group was Autumnalis followed by Ballum. The serovars Hardjo, Pomona, and Icterohaemorrhagiae were not present in the army horses, whereas all serovars studied were detected in urban working horses. Although no horses studied presented clinical signs of leptospirosis, the study confirms exposure to Leptospira spp. and the importance of studying in more detail the livelihood conditions in which working horses are kept and possible risk of transmission to their owners.