Epidemiological status of bovine leptospirosis in the State of Parana, Brazil

The objective of this study was to determine the prevalence of antibodies against Leptospira spp and their geographic distribution and to identify the risk factors associated with this disease in cattle herds with reproductive activity in the state of Parana. A total of 14 163 females aged >= 24 months originating from 1 926 herds that were not vaccinated against Leptospira spp were evaluated. To detect the Leptospira spp antibodies, all serum samples were submitted for a microscopic serum-agglutination test (MAT). An epidemiological questionnaire was performed at each farm visited to characterize the management practices and study the risk factors associated with the presence or absence of Leptospira spp. To perform geoprocessing, the geographical coordinates of each farm were recorded with a Global Positioning System (GPS), which were then used to create a map. The apparent prevalence of bovine leptospirosis in the herds was the parameter used to generate the final risk map. The apparent prevalences of seropositivity in the herds and animals in Parana state were 54.28%(95% CI: 52.05-56.51) and 37.70%(95% CI: 34.54-40.86), respectively. Multiple logistic regression analysis revealed that the risk factors associated with leptospirosis due to any serovar were the rental of grazing areas [OR=1.91(1.36-2.68)], presence of horses [OR= 1.59(1.28-1.97)], presence of > 20 females >= 24 months of age [OR= 2.25(1.46-3.49)], presence of > 49 bovines [OR= 2.78(1.82-4.26)], purchase of animals for reproduction [OR= 1.96(1.59-2.41)] and presence of calving pens [OR= 1.32(1.04-1.68)]. Risk factors for leptospirosis due specifically to serovar Hardjo were the presence of > 49 bovines [OR= 3.05(1.94-4.80)], presence of > 20 females >= 24 months [OR= 2.38(1.50-3.79)], presence of horses [OR= 1.87(1.45-2.43)], purchase of animals for reproduction [OR= 2.14(1.68-2.72)] and rental of grazing areas [OR= 2.22(1.54-3.21)]. Geographically, seropositivity to Leptospira spp by MAT identified the regions North/Northwest and Southwest in the state as the areas with a higher risk of disease occurrence.