During an American Legion veteran convention in a hotel in Philadelphia, over 200 participants developed a form of pneumonia and had to be hospitalised. This lung disease accompanied by high fever did not respond to treatment with standard antibiotics. Food poisoning was thought to be a reason even though the real reason behind the disease was still unknown. Among the veterans, 29 deaths were reported that created an unprecedented wave of panic. 34 people including people passing by contracted this disease. It was only after six long months of investigation that the ‘Center for Disease Control’ (CDC) Atlanta discovered in January 1977 a new bacterial species (Legionella) responsible for this disease named “Legionnaires’ disease” given the circumstances.