An outbreak of Legionnaires' disease linked to a contaminated cooling tower in Basel has killed one person and left 25 others hospitalised, with some patients requiring intensive care. A total of 26 cases have been recorded over the past two weeks in the Swiss city.
Authorities identified a water-operated rooftop cooling tower as the likely source and have shut it down. The bacterium spreads through inhaled aerosolised water droplets, and the vapour plume from a contaminated tower can carry the pathogen over 10 kilometres. The disease causes flu-like symptoms that can escalate to severe pneumonia, particularly in people with weakened immune systems or chronic conditions.
The mortality rate for Legionnaires' disease ranges from 5 to 10 percent even with antibiotic treatment. In neighbouring Germany, the Robert Koch Institute recorded 104 deaths from the disease in 2024.