Legionellosis, also known as Legionnaires’ disease, is an infectious disease caused by a family of bacteria Legionella.
There are more than 50 types of legionella strains. In France are the strains most commonly associated with legionellosis Legionella pneumophila.
How is legionellosis transmitted?
Bacteria are present in hot fresh water sources, but also in hot water mains, air conditioners, hot tubs, spas or even cooling towers. Because of this, legionellosis often develops in the form of an epidemic, since many people can be infected.
The disease is transmitted by inhaling contaminated droplets that are absorbed by the alveoli in the lungs. The bacteria then invade certain cells in the immune system called macrophages, which they eventually destroy.
On the other hand, the sick are not contagious and do not transmit the disease, since the bacteria present in hot water must be inhaled. Only one case of human-to-human transmission after very long exposure in a confined space has been reported in the literature.
Also read: A few simple steps to avoid contamination at home
What are the symptoms of legionellosis?
According to the Institut Pasteur, between 1,600 and 2,000 cases are reported in France each year, but many go undiagnosed or unreported. Symptoms appear 2 to 10 days after inhalation.
Legionellosis is responsible for an acute, sometimes fatal, lung infection. It presents with chest pain, coughing up blood (called hemoptysis), and difficulty breathing.
Other signs can occur such as cough, fever up to 39.5°, abdominal pain, nausea. A neurological disorder ranging from confusion to coma is also possible. Two complications are responsible for most deaths: acute respiratory failure and acute renal failure.
After being contaminated with Legionella, some people are at higher risk of developing a respiratory infection or complications. This is the case for smokers, people over 50 or immunocompromised patients.
How is legionellosis diagnosed?
Analysis of sputum or fluid collected in the lungs with a bronchoalveolar lavage enables the search for bacteria. They are then cultured to allow administration of the appropriate class of antibiotics.
A chest x-ray can also be used to assess lung involvement.
Also read: Argentina: Mystery pneumonia kills three people
The treatment of this bacterial disease is based on antibiotics, with the exception of penicillins, to which the bacteria are naturally resistant. Families of antibiotics such as macrolides or fluoroquinolones are most commonly used.
Prevention is fundamental. The regional health authorities remind you that it is possible to act at home with simple gestures:
– fEnvironment Let cold and warm water run at least once a week at little-used water points (sink, washbasin, shower, etc.), after each prolonged absence, for all water points before reuse (particularly the shower);
– SMonitor the temperature of hot water in the house: it must be very hot, but not “boiling” (minimum 50°C and maximum 60°C at the kitchen sink);
– Descale and disinfect fittings regularly (Jets, shower heads, etc.).
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