41 people fall ill

Source of infection for legionella diseases

Legionella spreads in water.

(Bild: Jöchl Martin)

Numerous legionella infections have been keeping Vorarlberg on tenterhooks for weeks. The search for the source of infection has been feverish. Now two sources of infection have been identified.  

Since the beginning of 2025, 41 people have fallen ill with legionella in Vorarlberg. Eight new cases have been added since the end of last week. 37 of these cases have occurred in the Lower Rhine Valley - the Bregenz region and surrounding area. The state's environmental institute has been investigating the source for weeks. Legionella contamination has now been detected in several private households as well as in cooling towers. For the first time, matches have also been found between the sequencing results of the sick persons and environmental samples. In the coming weeks, however, it will be necessary to observe whether further illnesses occur and whether there are any other sources.

The first analyses of the Legionella strains from several patients have been available since Wednesday. These patient strains show a strong genetic relationship, so it can be assumed that they were infected by the same source of infection, as the state reports.

Legionella was also detected in varying concentrations in several environmental samples. However, some environmental samples showed other types of legionella, which is why these are not a possible source of infection.

Cooling tower was taken out of operation
However, the same type of Legionella was detected in the cooling tower of a plant, which is why this cooling tower is a possible source of infection. The cooling tower was taken out of operation as soon as the legionella contamination was detected last week. The tower was also immediately disinfected and cleaned.

However, as it cannot be ruled out that other sources may have triggered these infections, the search for sources continues unabated.