Danger from the shower: What are Legionella bacteria?

Severe cases of pneumonia caused by Legionella infections occur repeatedly, most recently in a Duisburg apartment building and in a housing project in Berlin-Neukölln. After the limit for Legionella was exceeded in eight apartments, the health department imposed a shower ban in around 300 apartments. Tenants are criticizing the housing association responsible.

What are Legionella?

Legionella are rod-shaped bacteria that occur in small numbers in rivers, lakes, and groundwater. They also occur naturally in very small concentrations in drinking water.

These bacteria multiply best at temperatures between 25 and 45 degrees Celsius, which is why the pathogens find ideal growth conditions in building water pipes, air conditioning systems, warm-water swimming pools, and whirlpools. Biofilms can form in the pipes and in the rubber or plastic of the fittings, where the bacteria thrive.

When showering, droplets containing the pathogen can be inhaled via the atomized water vapor.

What are the symptoms of Legionnaires' disease?

If water contaminated with Legionella is swallowed, stomach acid kills the bacteria. However, if the bacteria of the genus Legionella pneumophila enter the lungs, they can cause severe pneumonia. This respiratory illness is known as Legionellosis or Legionnaires' disease. Cases of Legionnaires' disease occur worldwide; human-to-human transmission is not possible.

The first symptoms are high fever, chest pain, headache, chills, shortness of breath, cough, and weakness. Occasionally, vomiting, abdominal pain, and diarrhea may occur.

Most often, severe pneumonia develops, lasting about a month. In rare cases, Legionnaires' disease can be fatal. When Legionellosis occurs without pneumonia, it is called Pontiac fever.

People with weakened immune systems , such as the elderly or babies, as well as chronically ill people and smokers, are particularly at risk. Women are significantly less likely to become ill than men.

Legionella is easily detected with a urine test, but the test is not effective against all subgroups of the bacterium. Blood tests are also possible. If the disease is detected early, it can be effectively treated with antibiotics .

Where does the strange name come from?

Legionnaires' disease, of course, isn't just dangerous for mercenaries. The name comes from the disease's first discovery in 1976, when thousands gathered in Philadelphia to celebrate the bicentennial of the United States' independence.

One hotel also housed 182 war veterans from the American Legion, along with other visitors. 221 hotel guests contracted a type of flu, and 34 died. During the investigation into the cause, Legionella pneumophila bacteria were detected in the hotel's air conditioning system.

How can infections be prevented?

Germs and bacteria multiply particularly in stagnant water. If the pipes haven't been used for a long time, don't use the first water for drinking or brushing your teeth . Instead, let the cold water run first, then the hot water, with the window open, for a while until fresh water comes out of the pipes.

While we must use our precious drinking water responsibly, even in times of high water and heating costs, the temperature controls on boilers and hot water tanks should be set to at least 60 degrees Celsius. Legionella bacteria are killed at temperatures above 60 degrees Celsius.

Modern water heaters often have an automatic legionella protection system built in, which ensures that tap water is regularly heated to 70 degrees Celsius. In addition, the strainers on faucets and shower hoses should be soaked in vinegar or replaced regularly.

In public swimming pools, wellness facilities, and also in apartment buildings, owners are legally obliged to have the water regularly tested for Legionella by a specialist company.