What is Legionnaires’ disease, which killed three people in Italy recently

In the Milan region, three people died recently and 12 others are still in hospital after being diagnosed with Legionnaires’ disease or legionellosis. According to the health authorities, in April, this disease of bacterial origin affected at least 49 people.

Legionella bacteria

According to the World Health Organization (WHO), legionellosis It is “a disease with variable variability, from a mild febrile illness to forms of pneumonia that are sometimes fatal”. The WHO also says that Legionnaires’ disease is caused by exposure to bacteria species from the Legionella class, which are found in contaminated water and soil.

There are about 50 different types of Legionella, but one of them is the cause of the disease. The bacterium Legionella pneumophila, which is present in fresh water, is the most common cause and can be found in natural aquatic environments around the world, says the WHO. More than 90% of legionellosis cases are caused by Legionella pneumophila, an aquatic organism that lives at temperatures of 25-45°C, with the optimum temperature being around 35°C.

Legionnaires’ disease is contracted by ingesting water droplets (aerosols) contaminated with Legionella bacteria. These bacteria live in water and they multiply when the conditions are right for them: when water stops at 20-50 ° C in artificial water systems. For example, aerosols contaminated with Legionella can be emitted by running water from a faucet or shower, bubbles in spa water, or some air conditioning systems.

Risk of infection

There is a risk of infection where fine water droplets (aerosols) are created:

• showers and faucets,
• spa units/hot tubs,
• cooling towers and evaporative condensers used for air conditioning,
• decorative fountains, especially those that are placed inside,
• cooling display cases with a humidification system and other devices with fine spraying,
• pipe irrigation systems, used for watering plants in gardens.

Legionella bacteria can live in: in water at a temperature between 20°C and 50°C: • in tanks or troughs with hot and cold water, • in pipes with a reduced water flow or through which there is no water ‘ flow at all (this includes and those). in vacuum rooms), • in sediments (biofilms) and dirt on the inner surface of pipes and tanks, • on rubber and natural fibers in washing machines and sealing machines, • in boilers and hot water storage tanks, • in the deposits of stone and rust in pipes, showers and faucets.

Symptoms usually appear 2 to 10 days after being exposed to the Legionella bacteria. The disease begins with a headache, general muscle pain, fever of 40 ° C. Starting from the second, third day, the following symptoms appear:
– cough that can be productive, with sputum and sometimes blood,
– dyspnea (lack of air, breathing disorders),
– severe pain in the chest,
– gastrointestinal signs and symptoms, such as nausea, vomiting, diarrhea,
– confusion, anxiety and other mood changes,

Although legionnaires’ disease mainly affects the lungs, the causative bacterium can also cause infections at the level of wounds and injuries in the body, but also at the level of other organs such as the heart.

The name of this disease

Continued studies of the disease caused by Legionella bacteria have established a fundamental difference between two types of Legionnaires’ disease: an unusual, uneven form and a much more severe pulmonary form that can cause death in infected people. .

Diagnosing and treating the condition as early as possible is essential for a better prognosis and shorter recovery time. Especially for people in risk categories – the elderly, smokers, etc. – fast and quick treatment is very important.

The name legionellosis is due to an infection that occurred in 1976 at the American Legion convention in Philadelphia: out of 182 patients, 29 died. Later, it was discovered that a previously unknown bacteria, Legionella pneumophila , it spread through the ventilation system of the hotel that was hosting this event.