Control of Legionella in hospitals.

Legionellas are present in water distribution systems and cooling towers of many hospitals. No firm data are available regarding the need for prophylactic disinfection of these contaminated systems. Disinfection of water systems and cooling towers is an accepted and effective means of ending nosocomial Legionnaires' disease, but it should be performed in conjunction with good epidemiological and microbiological studies to pinpoint environmental reservoirs and disseminators. Chlorination, pasteurization, or both, are the only means of disinfection found to be effective in disease outbreaks. Prospective surveillance of immuno compromised patients with pneumonia is probably the most effective means to determine if a hospital is a source of Legionnaires' disease and, therefore, requires further investigations and disinfection.