The seroprevalence of Leptospira spp. and infection risk factors were investigated in horses from a military contingent in the Rio Grande do Sul State, Brazil. A total of 446 horses were evaluated and categorized into 309 mares, 11 stallions, and 126 horses with an average age of three years. To determine seroprevalence, serum samples from all horses were submitted to the microscopic agglutination test against 12 serovars belonging to nine serogroups, usually circulating in equine populations. To investigate the possible risk factors of infection by Leptospira spp., questionnaires were applied in that military unit. The seroprevalence in the horses with an average age of 3 years, mares, and stallions were 57.94% (73/126), 54.05% (165/309), and 45.45% (5/11), respectively. The main risk factors identified were contact with different water sources, the presence of rodents, and contact with wild and domestic animals. The high seroprevalence of anti‑Leptospira spp. antibodies may be associated with the presence of these risk factors. Therefore, the exposure of horses to possible reservoirs of Leptospira spp. should be minimized. Also, the immunoprophylaxis protocol should be reviewed and a shorter interval between vaccinations adopted to control leptospirosis in this herd.

The epidemiological characteristics of bovine leptospirosis in animals and herds in Mato Grosso do Sul were investigated to determine parameters such as disease frequency and the serovars reactant in beef cattle herds. A total of 4,629 beef cattle herds were examined against 33 Leptospira spp. serovars. The serum samples were submitted to the microscopic agglutination test (MAT) for the serological diagnosis of leptospirosis. The MAT results showed that 3,814 (82.39%) of the 4,629 animals evaluated were seropositive for the bacterium, with serological reactions mainly to serogroup Sejroe, serovar Wolffi (36.49%). The observed high frequency of reactive animals demonstrates the relevance of the infection. Therefore, general and specific measures should be implemented to contain and/or prevent infection of the animals in the studied region.