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Two outbreaks of Legionnaires’ disease leave three dead in France
Misting device thought the cause of most cases
Health authorities in two French regions have this week confirmed clusters of legionellosis, with a restaurant misting device blamed for dozens of cases near Chambéry and a second so far unexplained outbreak affecting a small town in Haute-Saône for the second year running.
Savoie: mister thought at fault for most cases
Health officials have identified the source of a summer-long outbreak around Chambéry: a poorly maintained misting device (brumisateur) used to cool diners outside a local restaurant.
Since June 1, 48 cases have been reported to health authorities in people aged between 26 and 91. Two people in their eighties have died, while others have required short hospital stays with respiratory problems.
Santé publique France and the National Reference Centre for Legionella have been investigating the rise in cases in Savoie since early June. Their inquiries found that 30 of those who fell ill had visited the same restaurant in the 14 days before symptoms began. As a precaution, the restaurant switched off its misting system on August 5, and no new cases linked to the venue have since emerged.
The regional health agency (Agence régionale de santé or ARS) in Auvergne-Rhône-Alpes, however, cautioned that this does not account for every case recorded in the department over the period. One of the two deaths, for example, has instead been traced to contamination from the victim's private water supply. The agency noted that in the majority of grouped Legionnaires’ disease cases investigated in France over the past 15 years, the source has never been identified.
Haute-Saône: second outbreak in a year
In Port-sur-Saône, near Vesoul in Haute-Saône, the ARS of Bourgogne-Franche-Comté has confirmed two further cases of Legionnaires’ disease between August 9 and 28.
The first case, reported on August 9, proved fatal. A second person, resident in the town, was declared infected on August 28 and remains in hospital. The source of contamination has not yet been established, and environmental and medical investigations are ongoing.
It is the second such episode to hit the town of around 3,000 residents in less than a year: in September 2025, six cases – two of them fatal – were identified among people living in or visiting the same neighbourhood.
A dedicated information line has been set up for residents with questions: 0805 200 550.
Between 70 and 150 cases of Legionnaires’ disease are declared each year across Bourgogne-Franche-Comté, with the health agency saying that the source is rarely formally identified.
What is Legionnaires’ disease?
Legionnaires' disease is a lung infection caused by legionella bacteria, which thrive in water systems. People become infected by breathing in fine contaminated water droplets – typically from hot water systems, showers, spa baths, jacuzzis or, less commonly, cooling towers, decorative fountains, misting devices or sprinkler systems.
The illness is not contagious and cannot be passed from person to person. Drinking tap water carries no risk – only inhaling contaminated droplets can cause infection.
Symptoms usually appear between two and 10 days after exposure and include high fever, a severe cough and, in older people, gastrointestinal problems. The disease can progress to breathing difficulties, requires antibiotic treatment and generally leads to hospitalisation. It proves fatal in around 10% of cases, mainly among those with weakened immune systems, including the elderly and those with chronic illness.
Protecting your home water system
French health authorities recommend the following precautions, which apply equally to permanent residents and second-home owners:
Running both cold and hot water at least once a week from taps that are rarely used (kitchen sink, washbasins, shower, etc.),
Running all taps before using them again (particularly the shower) after any prolonged period of absence,
Monitoring the hot water temperature at home. It should be very hot but not ‘boiling’ (at least 50°C and no more than 60°C at the kitchen sink),
Regularly descaling and disinfecting tap fittings (aerators, shower heads, etc.),
Using sterile water for biomedical devices (cleaning and filling oxygen therapy or sleep apnoea treatment devices).
Anyone who develops a high fever and cough, particularly after time spent in Savoie or Haute-Saône this summer, or after using a spa, shower or misting system, is advised to seek medical attention promptly and mention any relevant water exposure to their doctor.
