Human and animal leptospirosis in Southern Brazil: A five-year retrospective study.

BACKGROUND: Leptospirosis is an emerging zoonosis attributed to multiple reservoirs. Climatic conditions influence the transmission of pathogenic leptospires, which require warm and humid conditions for survival. The influence of seasonality in human and animal leptospirosis in the subtropical region of Brazil remains poorly understood.

METHODS: We performed a retrospective study to describe the patterns of human and animal exposure to leptospirosis and their association with precipitation events in Southern Brazil. Rainfall data were obtained from satellite images. Serum samples were tested using the microscopic agglutination test (MAT); samples with titer ≥ 100 were defined as seroreactive. Linear regression and Pearson's correlation were performed to assess whether there is a relationship between these variables.

RESULTS: We found that precipitation events were not significantly associated with the exposure to leptospirosis in humans or animal species, except for dogs. The interspecies analysis revealed an association between canine and human exposure to leptospirosis. Leptospira kirschneri serovar Butembo (serogroup Autumnalis) presented the highest seroreactivity in humans.

CONCLUSION: This study provides valuable insights in human and animal leptospirosis in Southern Brazil. These insights will be essential to design intervention measures directed to reduce disease dissemination.