Leptospirosis is a well-known disease that frequently occurs after floods. At the beginning of May 2024, a catastrophic flood occurred in the state of Rio Grande do Sul, Brazil, affecting two million people and leading to a state of calamity. Given the State’s high pre-flood leptospirosis rates, the disease became a major concern for decision-makers. This study aimed to estimate the rise in leptospirosis cases after the flood, assess the changes in case patterns before and after the disaster, and document the response of the state health surveillance center to the outbreak. We estimated the increase during the flood period (May to July 2024) by comparing it with the same period in the previous year as baseline. During the first three months of the catastrophic event, 6273 suspected cases of leptospirosis were reported to the surveillance system, and 958 cases were confirmed. The number of confirmed cases during the flood was 10.3-fold higher than the baseline. Spearman’s rank-order correlation coefficient was 0.77 (p-value < 0.0001) for the association of Health Regions regarding the rank in incidence rates of confirmed cases in the flood period and the proportion of the population with households flooded. Thirty deaths (three females) were confirmed, a 6.0-fold rise compared with 2023. The state responders carried out many activities, including epidemiological surveillance and the dissemination of information. Among the challenges faced was the lack of evidence in the literature supporting recommendations for antibiotic chemoprophylaxis for rescue personnel. Another difficulty concerned performing gold-standard laboratory diagnostic tests to confirm the enormous number of suspected cases reported during this catastrophe. Despite implementing many actions to mitigate its impact, leptospirosis remained a major challenge during the event. These findings may provide valuable insights for decision-makers facing similar situations in massive climate disasters.

Between November 2013 and June 2014, 56 cases of bacteremia (15 deaths) associated with the use of Total Parenteral Nutrition (TPN) and/or calcium gluconate (CG) were reported in four Brazilian states. We analyzed 73 bacterial isolates from four states: 45 from blood, 25 from TPN and three from CG, originally identified as Acinetobacter baumannii, Rhizobium radiobacter, Pantoea sp. or Enterobacteriaceae using molecular methods. The first two bacterial species were confirmed while the third group of species could not be identified using standard identification protocols. These isolates were subsequently identified by Multi-Locus Sequence Analysis as Phytobacter diazotrophicus, a species related to strains from similar outbreaks in the United States in the 1970’s. Within each species, TPN and blood isolates proved to be clonal, whereas the R. radiobacter isolates retrieved from CG were found to be unrelated. This is the first report of a three-species outbreak caused by TPN contaminated with A. baumannii, R. radiobacter and P. diazotrophicus. The concomitant presence of clonal A. baumannii and P. diazotrophicus isolates in several TPN and blood samples, as well as the case of one patient, where all three different species were isolated simultaneously, suggest that the outbreak may be ascribed to a discrete contamination of TPN. In addition, this study highlights the clinical relevance of P. diazotrophicus, which has been involved in outbreaks in the past, but was often misidentified as P. agglomerans.

Leptospirosis is an endemic zoonotic disease in Brazil and is widespread throughout rural populations in the state of Rio Grande do Sul. This study aimed to identify presumptive infecting Leptospira serogroups in human and animal cases and describe their occurrences within the ecoregions of the state by animal species. Data for human and animal leptospirosis cases were gathered from the government’s passive surveillance systems and presumptive infecting serogroups were identified based on a two-fold titer difference in serogroups in the microscopic agglutination test (MAT) panel. A total of 22 different serogroups were reported across both human and animal cases. Serogroup Icterohaemorrhagiae was the most common among humans, while serogroup Sejroe predominated among animal cases, particularly bovines. Each ecoregion had a large distribution of cases, with 51% of the human cases in the Parana–Paraiba ecoregion, and 81% of the animal cases in the Savannah ecoregion. Identifying and mapping the serogroups circulating using the One Health approach is the first step for further understanding the distribution of the disease in the state. This study has the potential to aid in guiding public health and agricultural practices, furthering the need for a human vaccine in high-risk populations to complement control and prevention efforts.