What is Legionella and how does it spread? Legionella is a gram-negative bacillus, responsible of a severe infective disease called Legionnaires’ disease. Legionella survives in water and mud and it is transmitted by air. Moreover it has been ascertained its transmission by the air conditioning central system.   The Legionnaires’ disease is a pulmonary infection caused by the Legionella pneumophila bacterium, which name means exactly “Legionella lover of the lungs”. The name...