Book excerpt: Water is the major natural reservoir for legionellae, and the bacteria are found worldwide in many different natural and artificial aquatic environments, such as cooling towers, water systems in hotels homes, ships and factories, respiratory therapy equipment, fountains misting devices and spa pools. This book provides a comprehensive overview on the sources, ecology and laboratory diagnosis of legionella. Guidance is provided on risk assessment and risk management of susceptible environments. The necessary measures to prevent, or adequately control, the risk from exposure to legionella bacteria are identified for each identified environment. Outbreaks of legionellosis generally cause a high level of morbidity and mortality in the people affected and as such the suspicion of an outbreak warrants immediate action. The policies and practice for outbreak management and the institutional roles and responsibilities of an outbreak control team are reviewed. This book will be useful to all those concerned with legionella and health, including environmental and public health officers, health care workers, the travel industry, researchers and special interest groups.