A-Z Index × Submit A-Z Index × Submit A-Z Index Search Dropdown × Submit Facebook Twitter LinkedIn Syndicate Emerging Infectious Disease journal ISSN: 1080-6059 Disclaimer: Early release articles are not considered as final versions. Any changes will be reflected in the online version in the month the article is officially released.
After 4 urban river surfers in Munich, Germany, were hospitalized with severe leptospirosis, we conducted a controlled cross-sectional study. Leptospira IgG seroreactivity was more frequent among surfers than controls, and Leptospira DNA was detected in 1 soil sample. Freshwater surfing could represent an underrecognized exposure setting in temperate cities.
Leptospirosis is usually associated with tropical and subtropical regions, but reports have noted increasing case numbers in temperate countries ( 1 , 2 ). Pathogenic Leptospira spp. are shed in the urine of reservoir animals, particularly rodents ( 3 ). Human infection occurs primarily through contact with contaminated water or soil ( 4 ). Recreational freshwater exposure is a recognized risk factor, and investigations have revealed outbreaks linked to water sports, including river surfing, in Europe ( 5 , 6 ). However, data on Leptospira exposure in urban freshwater settings remain limited. In Germany, available seroprevalence data suggest low background exposure (1.6%–4.2%) in the general population ( 7 , 8 ).
Video . A surfer on the Eisbach River wave, an urban river location in Munich, Germany, associated with exposure to Leptospira spp.
During 2021–2024, four previously healthy men who regularly surfed the Eisbach River wave in Munich, Germany, were diagnosed with severe leptospirosis. We investigated whether regular surfing the Eisbach River wave ( Video ) was associated with increased serologic evidence of Leptospira exposure.
We conducted a controlled, cross-sectional study during September 4–November 7, 2024, comparing Eisbach River surfers with nonsurfing controls selected to achieve similar age and sex distribution. We did not perform individual matching. We recruited surfers on site at the Eisbach River surfing wave, an urban side arm of the Isar River; we recruited controls from a pool of employees at Technical University of Munich University Hospital. Eligible surfers had surfed the Eisbach > 3 times during the 12 months before study enrollment; controls reported no river surfing during that period. Participants were > 18 years of age and had no known history of leptospirosis.
Participants completed a standardized questionnaire assessing demographics, travel history, animal contact, and symptoms consistent with leptospirosis during the 12 months before study enrollment ( Appendix ). We obtained blood samples for serologic testing and PCR. We collected 15 environmental water and soil samples at the Eisbach surfing site on 5 sampling days during September 2024, including river water samples at the standing wave and soil samples from both banks at the surfers’ entry and exit areas.
The Leptospira Reference Laboratory of the German Federal Institute for Risk Assessment (Berlin, Germany) tested samples for leptospiral IgG using an in-house ELISA ( 9 ). We classified borderline and positive IgG results as seroreactive because we aimed to detect prior exposure rather than acute infection. We used microscopic agglutination test (MAT) on IgG-positive samples to assess detectable serogroup-specific agglutinating antibodies and determine serog…