Two cases of Legionnaires' disease, including one fatal infection, have been identified in the eastern French town of Port-sur-Saone, health authorities announced on Tuesday.
The Bourgogne-Franche-Comte Regional Health Agency (ARS) said the cases were detected between August 9 and August 28 in the commune located near Vesoul.
The first case was reported on August 9 in a patient who later died, according to the health agency. Medical and environmental investigations are currently under way to determine the source or sources of contamination.
A second case of the pulmonary infection was declared to health officials on Friday, August 28. The patient resides in Port-sur-Saone and is currently hospitalised.
Health officials stressed that the exact origin of the contamination causing the infections has not yet been established. The agency has set up a public information telephone hotline on 08.05.20.05.50 to address questions from local residents.
Previous outbreak in the commune
The new cases follow a cluster of infections in the same municipality last year. In September 2025, six cases of Legionnaires' disease, including two deaths, were identified in Port-sur-Saone.
All of those earlier cases were diagnosed in people who resided in or had visited the same neighbourhood within the town.
Port-sur-Saone is a river commune in the Haute-Saone department of eastern France, situated along the Saone river roughly 12 kilometres north-west of Vesoul. The ARS operates as the regional health authority responsible for epidemiological monitoring, sanitary control, and public health responses across Bourgogne-Franche-Comte.
Understanding Legionnaires' disease
Legionnaires' disease is a severe form of pneumonia caused by Legionella bacteria. Infection occurs when people inhale microscopic droplets of contaminated water from sources such as industrial cooling towers, air conditioning systems, or showers, rather than through direct person-to-person transmission.
The disease primarily affects adults and poses a heightened threat to vulnerable groups. Those at higher risk include immunocompromised individuals, people with pre-existing conditions or chronic respiratory illnesses, diabetic patients, and smokers.
Health authorities note that the infection is fatal in approximately 10 per cent of cases. Across the Bourgogne-Franche-Comte region, between 70 and 150 cases of Legionnaires' disease are reported to the health agency each year.
The agency emphasized that it is rare for investigators to formally identify the exact environmental source of contamination in Legionnaires' disease outbreaks, though medical and environmental inquiries into the Port-sur-Saone cases remain ongoing.
