In July 1976, an outbreak of a disease occurred in Philadelphia (USA), which was later named Legionnaires' disease or legionellosis.
The outbreak was caused among American Legion war veterans gathered for a convention. Of the 4,400 participants, 182 fell ill and 29 died.
Legionnaires' disease is a sapronotic (from the word earth), a bacterial acute infectious disease with an aspiration mechanism of pathogen transmission, in severe cases it is characterized by fever, pneumonia, damage to the gastrointestinal tract, kidneys and central nervous system.
As it turned out later, the disease is widespread. It manifests itself in 3 forms: legionellosis itself, Pontiac fever and Ford-Bragg fever.
The causative agent of the disease is Legionella, a movable rod with flagella. Stable in the external environment: in a liquid environment at t0= 250 C, it can be stored for up to 112 days, at + 40 C – 150 days. Very sensitive to disinfectants.
The natural habitat of the pathogen is fresh, open reservoirs with warm water, where they live together with green algae. The infection is not transmitted from person to person. The period of contagion is indefinitely long. The natural habitat of the pathogen is also air conditioning systems, showers, in aerosols that are formed during repair work of swimming pools, water parks, molding excavations, and in shower horns.
The transmission mechanism of the pathogen is aspiration, with airborne dust and airborne droplet transmission routes.
Infection occurs by inhaling infected water droplets or soil particles.
Natural susceptibility is high - with Pontiac fever it reaches 95%. In the pneumonic form - on the contrary - up to 5%. However, the mortality rate is extremely high.
The development of the disease is facilitated by old age, alcohol consumption, smoking, drug addiction, diabetes mellitus, and congenital immunodeficiency.
The immunity is stable, there were no repeated cases of the disease.
Prevention of legionellosis includes the following:
1. Periodic cleaning of air conditioners (in hotels, hospitals);
2. Disinfection of water in shower systems, as well as air conditioners;
3. Bringing t0 of water to + 600 C and above;
4. Installation of effective ventilation in molding shops;
5. Use of respirators during repair work;
6. Giving up bad habits: alcohol, smoking, drug addiction;
7. Carrying out preventive disinfection in the outbreak.
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