Linz Legionella outbreak reaches 29 cases after new infection

Authorities in Linz reported another Legionella infection on Tuesday, bringing the number of infected people to 29, ORF reported, citing the state of Upper Austria, Linz city authorities and the Agency for Health and Food Safety.

The exact source of the infections remains unclear. Three patients have died since the outbreak began on July 20.

Authorities have so far sent 190 water samples to the Agency for Health and Food Safety. About three quarters have already been examined and evaluated.

Experts found several Legionella variants in a water sample from a cooling tower at a Linz AG cooling facility, including Legionella pneumophila of the Allentown subtype. The same subtype was also detected in three epidemiologically linked cases.

However, the genetic analyses available so far do not provide conclusive evidence that the cooling facility was the source of the infections. Further tests are still pending. Linz AG said the drinking water supply was not affected.

The facility is located on the roof of Linz AG’s power grid building. It has since been cleaned and disinfected, and its water has been replaced. On Monday, Linz AG also switched the facility to dry operation, which was possible because of the current temperatures.

Legionella bacteria can multiply in water. According to the Agency for Health and Food Safety, the main risk arises when contaminated water droplets or aerosols are inhaled. This can cause Legionnaires’ disease, a severe form of pneumonia.

Milder infections without pneumonia are also possible. Known as Pontiac fever, they usually clear up on their own within a few days, according to the agency. People with weakened immune systems, chronic lung diseases and smokers face a higher risk of severe illness.