Leptospirosis is an infectious disease caused by the bacterium Leptospira, with high lethality potential, high incidence, and strong influence of environmental factors on its transmission. This study analyzed the epidemiological scenario of leptospirosis in Santa Catarina (SC), between 2019 and 2024, considering the different macroregions and the occurrence of floods, with the objective of identifying the areas with the highest incidence and understanding the influence of environmental factors on infection. Ecological study using data on cases and deaths from leptospirosis, and the presence of water/mud/flooding associated with the case, in the macroregions of SC, between 2019 and 2024, based on SINAN notifications via DATASUS. Incidence and lethality per 100,000 inhabitants were calculated using IBGE population data. For spatial analysis, a thematic map of the macroregions was built in Datawrapper. The association between floods and cases was verified using the chi-square test (p < 0.05). The macroregions with the highest incidence rates were Serra Catarinense (27/100,000 inhabitants) and Vale do Itajaí (14/100,000). The highest lethality rates occurred in Serra Catarinense, Meio-Oeste, and Grande Oeste, at 2%. The average incidence rate in the state was 10.53/100,000 inhabitants/year, and overall lethality was 1.12%. The presence of water/mud/flooding was associated with at least 13% of cases, being significantly higher in Vale do Itajaí (34.2% of cases; X² = 74.2; p < 0.001). The analysis identified Vale do Itajaí and Serra Catarinense as the macroregions with the highest incidence, and Serra Catarinense, Meio-Oeste, and Grande Oeste with the highest lethality rates. The findings reinforce the influence of extreme climatic events associated with characteristics of relief, urbanization, infrastructure, and access to health services on the transmission of leptospirosis. Despite the limitations inherent to the ecological design, the results point to the urgency of targeted public policies, such as active surveillance in endemic regions, strengthening urban drainage infrastructure, and early flood warnings. The study contributes to planning integrated actions between epidemiological surveillance, environmental management, and primary care, aiming to reduce the incidence of leptospirosis in SC.
Bueno et al. (2026) studied this question.