Legionnaires' Disease Outbreak Linked to Biomass Condensing Boiler in France

A recent Legionnaires' disease (LD) outbreak in the Strasbourg metropolitan area, France, has been linked to a collective biomass condensing boiler. The outbreak, which occurred between November 1 and December 12, 2019, resulted in 28 cases, with two fatalities. Epidemiological, environmental, and genomic investigations were conducted to identify the source of the outbreak and understand its spread. Research led by the University Hospital of Lyon revealed that the boiler's poor maintenance and warm weather allowed Legionella pneumophila (Lp) 1 to proliferate within the system, leading to contamination levels of 105-106 CFU/L.

Key Takeaways:

• The outbreak occurred in the Strasbourg metropolitan area, France, between November 1 and December 12, 2019.
• A total of 28 cases were diagnosed, with 14 males and 14 females, and a median age of 70 years (range: 42-88 years).
• Two fatalities were reported, with one case showing typing revealed serogroup 1 (Lp 1) sequence type (ST) 62 infection.
• Environmental investigations revealed high Lp 1 contamination levels within the biomass condensing boiler.
• Genome sequencing data showed that the environmental isolates and clinical isolates clustered with zero to two single nucleotide polymorphisms.
• The research highlights potential LD risks arising from innovative energy-saving heat production processes designed to reduce greenhouse gas emissions.

Statistics:

• 28 cases of Legionnaires' disease were diagnosed in the outbreak.
• 14 males and 14 females were affected.
• The median age of the cases was 70 years.
• 105-106 CFU/L of Legionella pneumophila (Lp) 1 was detected within the biomass condensing boiler.
• The outbreak resulted in two deaths.

Sources:

• Eurosurveillance: "A community Legionnaires' disease outbreak linked to a collective biomass condensing boiler, France, 2019"
• University Hospital of Lyon: GenEPII Sequencing Platform, Institut des Agents Infectieux