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Alisea News

05/11/2015

Legionellosis risk at schools: how to prevent it?

Legionellosis often represents a not considered risk in biological risk evaluation of schools, but epidemics have been discovered in environments like schools, hotels and hospitals

24/10/2015

Evidences of legionellosis in a Capannoli plant

Security measures has been immediate for the infected rooms. These measures have been activated by a major's decree to debilitate the dangerous bacterium


Hazards

The Legionella Pneumophila was first isolated as an etiological factor in 1976, when a violent case of epidemic pneumonia broke out among American Legion ex-servicemen, attending a convention at the Westin Hotel in Philadelphia (USA).

Legionella Pneumophila: a serious danger to human health

Legionellosis or “Legionnaires Disease” is a serious infective illness characterised by a high mortality rate.

Read more

Clinical cases

Infection by Legionnaires’ could give rise to two distinct clinical cases: “Pontiac fever” and “Legionnaires’ Disease”.

Read more


Legionella Pneumophila: a serious danger to human health

Legionellosis or “Legionnaires Disease” is a serious infective illness characterised by a high mortality rate.

The definition of Legionellosis includes all forms of disease caused by gram-negative aerobic bacteria of the Legionella genus, which can occur both as pneumonia, and in an extra-pulmonary febrile illness or in subclinical form.

Legionella bacteria are in nature normally found in water surroundings, such as waterways, lakes, thermal waters, etc. From such a natural reservoir, however, the microorganisms can pass on to sites which act as an artificial reservoir (water and air conditioning systems, swimming pools, fountains, irrigation systems etc.), following the waterway in which they live.

The usual way of transmission to man is normally through the respiratory channel, by the inhalation of aerosol particles containing Legionnaire bacteria, or of particles arising during drying. Currently, the main systems generating aerosol particles associated with the transmission of illnesses include air conditioning systems, water systems, equipment for assisted respiratory therapy, whirlpools, swimming pools and decorative fountains. Scientific literature has moreover indicated cases of Legionellosis caught by the aspiration or micro-aspiration of contaminated water and cases of Legionellosis caught from a wound. Interpersonal transmission has never been scientifically shown to exist. The microorganism is ubiquitous and the illness can occur with epidemics due to a single source having a limited exposure to the etiological agent in time and space, or with a series of independent cases in a highly endemic area, or even with sporadic cases without any evident temporal and geographic link.

Epidemic breeding grounds repeatedly occur in communal environments where people transit such as hospitals and hotels.

The use of preventive measures, even if they are expensive, appear to be justified by the high mortality rate of Legionellosis: 5-15% of the infections originating within the EU and 30-50% of those having a nosocomial origin. In patients having precarious clinical conditions and in those treated late the mortality rate can reach 70-80% of cases.

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Clinical cases

Infection by Legionnaires’ could give rise to two distinct clinical cases: “Pontiac fever” and “Legionnaires’ Disease”.

“Pontiac fever”, after an incubation period of 24-48 hours, appears in an acute form without any lung involvement, flu-like, and passes in 2-5 days. Its premonitory symptoms are: general discomfort, muscle pain and headache, followed quickly by fever, at times with coughing and a sore throat. Diarrhoea, nausea and light neurological symptoms such as vertigo or photophobia can also follow.

“Legionnaires’ Disease”, after a period of incubation varying from 2 to 10 days (on average 5-6 days), it appears with lung involvement having a lobar characteristic which is clinically significant or of discreet gravity, with or without extra-pulmonary symptoms.

The pulmonary picture has an abrupt onset with discomfort, headache, fever and osteoarthralgia, a light non productive cough which gets worse when the respiratory symptoms appear. An objective chest examination shows areas of mono or bilateral parenchymal consolidation, with hypophonesis and the presence of crackling rales. The radiological report is not pathognomonic. At times gastrointestinal, neurological and cardiac symptoms can be present; alterations of the mental state are common but they are not signs of meningism. If a patient affected by Legionellosis shows mental confusion, they also generally have one or more of the following symptoms: relative bradycardia, a light increase of the transaminase, hypophosphatemia, diarrhoea and abdominal pain.
Among the complications of Legionellosis there could be: pulmonary abscess, empyema, respiratory insufficiency, shock, disseminated intravasal coagulation, thrombocytopenic purpura and renal insufficiency.

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