It is a pneumonia whose number of cases is clearly increasing ... but which has nothing to do with the coronavirus. According to the last epidemiological bulletin published by Santé publique France, 2,133 cases of legionellosis were recorded in 2018 in the country, i.e. 31% more than the previous year. In early February, a 71-year-old woman was disembarked from a cruise in Marseille, in serious condition. She suffered from this bacteria. But it is probably in June 2018 that the contaminations were most numerous.
One of the hypotheses to explain this upsurge is the influence of the weather at this time of the year, with temperatures and precipitation higher than usual, which could favor the survival of legionella. If the majority of infections remain unexplained, some patients have evoked a trip, mostly in France.
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Why is this disease called legionellosis?
This disease was first recognized in July 1976. That year, the 58th Congress of the American Legion, a congress of veterans of the American army, was held from July 21 to 24 in Philadelphia, at the Bellevue-Stratford hotel. The air conditioning system, dating from 1954, shows some signs of weakness.
A young employee is responsible for monitoring it, but he falls ill the day before the convention. On July 23, two organizers and several legionaries in turn suffered from a "bad cold". On July 26, many of the delegates were bedridden and on July 30, four legionaries died of pneumonia. Back home after the convention, several ex-soldiers are hospitalized.
Doctors in different states are gradually making the connection between their patients' symptoms and their presence in Philadelphia. At the end of this first epidemic, there were 182 cases, including 29 deaths. But it was not until December 27 that a doctor observed a new bacteria on the fragment of the lung of a deceased organizer. This bacterium, responsible for the epidemic, will be baptized a few years later Legionella pneumophilia .
How do you get this bacteria?
Legionella occurs naturally in fresh water, in lakes and rivers, and in moist soils. From the natural environment, the bacteria can colonize installations that offer conditions favorable to their development, such as stagnation of water, a temperature between 25 and 45 ° C, and the presence of nutrients. Contamination is by respiratory route, by inhalation of contaminated water diffused in aerosol.
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What are the symptoms ?
Legionnaire's disease is associated with severe acute community-acquired pneumonia (CAP). All the cases declared in France (98%) are hospitalized and the overall mortality is 15% (30% in immunocompromised patients).
After an incubation period of two to ten days, the onset of the disease is progressive, patients present with flu-like syndrome with fever, headache, myalgia, anorexia. Once the disease is fully established, symptoms combine a fever high at 40 ° C, dyspnea and a severe cough, which can be accompanied by sputum. Pneumonia is often associated with digestive signs (50% of cases) such as diarrhea or abdominal pain, and neurological signs (40% of cases) such as confusion, hallucinations, signs of focusing, coma.
How to prevent contamination?
It is better to be wary of sanitary facilities that have not been used for a while. By opening a shower that has been closed for a long time, for example in a campsite, the user will receive an aerosol of bacteria, including legionella. The best thing to do is to let the water run for 5 to 6 minutes before washing.