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The advice of Legionellosis disease during a heat wave

Legionellosis disease: watch out for air conditioners and hot tubs during a heat wave

Legionellosis disease: watch out for air conditioners and hot tubs during a heat wave

With the return of the heat wave, watch out for air conditioners and hot tubs, as the water in these units can get hot and create bacteria like Legionella. Here's how it works.

With the new heat wave, temperatures are rising. To cool down, turn on the air conditioner or get in the hot tub (if you're lucky enough to have one...), but it's not always harmless. Bacteria love hot water and can be very dangerous, such as the bacteria that cause legionellosis.

Where does legionellosis come from and how is it transmitted?

"Legionellosis is a potentially fatal bacterial disease. The recent emergence of the disease is explained by its association with modern water supply systems, e.g., hot water networks, cooling towers, hot tubs, etc.

Legionella bacteria are found in aquatic flora and frequently in thermal water. They are very heat resistant (which they love!) at temperatures between 30 and 60 degrees. In 1976, the first outbreak occurred in a hotel due to an air conditioning system in which Legionella pneumophila bacteria had colonized. Twenty-nine people died.

It is transmitted by infectious aerosols from the aquatic environment. "After inhalation of the aerosols, the bacteria are taken up by the alveoli and then enter the macrophages, the cells of the immune system, which destroy them," according to the Pasteur Institute. Legionellosis, however, is not transmitted from person to person.

What are the symptoms of legionellosis?

The symptoms of legionellosis are not much different from those of covid-19 or influenza. It may present 2-10 days after infection with dry cough, fever (which increases), abdominal pain, intestinal problems, and acute pneumonia.

Complications may include kidney or lung failure. If left untreated, neurological problems occur and can lead to coma.

How can it be detected and treated?

Like Covid-19, legionellosis can be detected by PCR testing. If the disease is resistant to the penicillins prescribed to treat pneumopathy, it can be treated with other antibiotics: Macrolides, fluoroquinolones, and rifampicin. They are administered for 14-21 days.

It is estimated that between 1 600 and 2 000 cases occur each year in France. However, reported cases of legionellosis mainly affect people admitted to intensive care units," according to the Ministry of Health's website. "Recovery usually occurs after a few weeks or even months.

How can it be prevented?

Legionella can multiply more quickly in hot weather, as water in a hot tub or air conditioner gets hotter, creating a favorable environment for Legionella to spread. But can Legionella also grow in water pipes, the sink, or the shower if the water is not circulated for a while?

To avoid this phenomenon, the Ministry of Health recommends that water be circulated regularly (once a week) and after prolonged absences at water points that are rarely used in the home. The water temperature in the sink should be between 50 and 60 degrees. Faucets should be cleaned and disinfected regularly.

In the case of air conditioners, manufacturers must explain how to treat the water they contain to avoid these risks. Maintenance is therefore very important. For hot tubs: Clean them (filters and walls) every week, use appropriate water treatments, and pay attention to the pH (between 7.2 and 7.4).


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