The control of Legionella within buildings

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. Legionella is a pathogenic genus and discovery of any species of Legionella in significant numbers in an engineered water system warrants immediate attention. Legione/la is a ubiquitous bacterium, which means that it is a naturally occurring organism widely found in nature. Most natural surface waters such as lakes contain Legionella and it can also be found in soil samples.