Person dies in Wetzikon after Legionella infection

A middle-aged person has died in Wetzikon in canton Zurich after contracting legionellosis, SRF reported. The death occurred last week. The city has recorded 33 cases since the beginning of 2025, but investigators have not identified a common source of infection.

The deceased had several pre-existing health conditions, the Zurich Cantonal Health Office said. It is not yet known where the person became infected, and the investigation is continuing.

All 33 people who contracted legionellosis received medical care. Most required hospital treatment but have since been discharged.

Investigators examine shower water

The cases occurred at different times and in different places. Investigations into several cases indicate a possible link between the illnesses and the presence of Legionella bacteria in shower-water samples. However, tests of other possible sources have not identified a common source of infection.

The investigations will continue and be expanded. The health authorities and the city of Wetzikon are preparing an information sheet for property managers and owners, including recommendations for professionally inspecting and safely operating building water systems. The city also plans to increase public awareness of preventive measures.

No new recommendations currently apply to residents. The general preventive measures against Legionella that have already been communicated remain in force. Drinking water in Wetzikon is safe to drink, and drinking water does not cause infection.

Legionella bacteria occur naturally in water but can multiply in building water systems when temperatures range from 25 to 45 degrees Celsius or when water remains stagnant for extended periods. Infection occurs by inhaling very fine droplets of water containing the bacteria, not through person-to-person transmission or by drinking water.

If the bacteria enter the respiratory tract, they can infect the lungs and cause legionellosis, also known as Legionnaires’ disease. The disease can lead to severe pneumonia. Older people, people with chronic lung diseases and smokers face a higher risk of becoming ill, although most people do not become sick after contact with the bacteria.

In August, an outbreak of Legionella infections in Basel caused one death and left 28 people ill.