<prompt> Legionnaire disease causes?Respiratory diseaseU.T.IRetroperitoneal fibrosisAcute gastroenteritis  <response>: Ref: Page 1138: Harrison 20th edition The bacterium L. pneumophila leads to legionnaire disease. The most common form of transmission of Legionella is inhalation of contaminated aerosols produced in conjunction with water sprays, jets or mists. It has 2 distinct clinical syndromes: Legionnaires disease, which most often manifests as severe pneumonia accompanied by multisystemic disease, and Pontiac fever, which is an acute, febrile, self-limited, viral-like illness 