Legionellosis

Pathogen

Legionella are gram-negative, non-spore-forming aerobic bacteria.

Occurrence

Legionella are widespread environmental germs. Under certain conditions Legionella colonize artificially created water systems.

Modes of transmission

Infection usually occurs through inhalation of aerosols containing Legionella, but (micro)aspiration of contaminated water can also lead to infection in rare cases. The following technical systems can be considered as potential sources of infection:

Domestic installations for hot water distribution, also cold water supplies, if the temperature in the pipes rises above 25 °C, e.g.:

• Residential buildings, hospitals, nursing homes, hotels
• Air conditioning systems
• Swimming pools/bathing pools, whirlpools
• Other technical apparatus (e.g. dental units, oral irrigators, inhalers).

Incubation period

• Two to ten days Legionnaires' disease (legionellosis with pneumonia)
• Five to 66 hours Pontiac fever (legionellosis without pneumonia)

Duration of infection

Direct transmission from person to person is not known so far.

Disease pattern and course

Legionnaires' disease:

• Beginning with malaise, headache and pain in the limbs, irritable cough, chills, temperature rise to 39°-40°C,chest pain, pneumonia.

Pontiac fever:

• Beginning with mild flu-like symptoms with headache and limb pain, chest pain, dry cough, and fever. Pneumonia does not occur.

Therapy

Only antibiotics are effective against Legionella.

Obligation to report

According to § 7Abs. 1 Infektionsschutzgesetz (IfSG) the direct or indirect detection of an acute infection by Legionella spp. has to be reported.