Legionnaires' Disease in Elderly People: The First Sign of an Outbreak in the Community?

Legionella pneumophila is responsible for up to 5% of cases of community-acquired pneumonia and mainly affects people aged over 50 years. The confirmation of legionellosis in two elderly patients living close to each other prompted a search for other cases. A total of eleven subjects with legionnaires' disease was recognized. The clinical findings are described and the diagnosis of legionellosis is discussed. Environmental investigations pointed to a cooling tower in the local town centre as the probable source of infection.