The causative agent of Legionnaires' disease is the bacterium Legionella pneumophila (Lp). This organism is just one species of the genus Legionel/a. To date more than 36 species of Legionella have been isolated and these are being further divided into serogroups and subgroups. Approximately 90% of cases of Legionnaires' disease have been associated with· Lp serogroup 1, subgroup Pontiac. However about half of the known species of Legionel/a have caused serious disease and several fatalities in man.

A renewed interest in energy conservation has spaumed a revival of community-based energy management projects throughout the United States and Canada.