Legionnaires' disease.
D000328:Adult; D000368:Aged; D004196:Disease Outbreaks; D005455:Fluorescent Antibody Technique; D006801:Humans; D007877:Legionnaires' Disease / Q000209:etiology*; D008875:Middle Aged; D010414:Pennsylvania; D012141:Respiratory Tract Infections / Q000209:etiology*