Autecology of Legionella pneumophila.

Species of Legionella are readily isolated from freshwater aquatic habitats throughout the United States, which are diverse in their physical and chemical parameters. Temperature studies indicate that Legionella is not present in habitats with temperatures above 63 degrees C, and isolates have been obtained from frozen rivers. The presence of the organism in natural hot springs and man-made thermal habitats suggest that Legionella may have been present for a long period of time, but has only recently had man-made thermal habitats suitable to establish niches common to man.