Epidemiologic Investigation Tools
Diagnostic Tests to Confirm Legionnaires' Disease
Urinary antigen assay and culture of respiratory secretions on selective media are the preferred diagnostic tests for Legionnaires' disease. Consult Diagnostic Testing for details.
Case Verification and Patient Interview
- Legionellosis Case Report Form [2 pages]
Completed case report forms should be forwarded to the Respiratory Diseases Branch Legionellosis Program within 7 days for travel-associated cases and within 30 days for non-travel cases.
- Hypothesis-Generating Questionnaire [6 pages]
After confirming a case of legionellosis and completing the CDC Legionellosis Case Report Form, this form can be used to collect additional epidemiologic data that may be useful in detecting outbreaks or in a future cluster/outbreak investigation. This form may be added to your state’s electronic notifiable disease surveillance system in whole or in part for routine data collection. A more detailed questionnaire that is customized to the outbreak location should be completed if the case is associated with a known outbreak.
- Legionellosis Cruise Ship Questionnaire [6 pages]
After confirming a case of legionellosis and completing the CDC Legionellosis Case Report Form, this form can be used to collect additional epidemiological data for cases that may be cruise ship associated.
Environmental Assessment and Sampling
- Environmental Assessment of Water Systems [13 pages]
- Environmental Testing Guidelines [3.6 MB, 15 pages]
Also available as a web page.
- Protocol for Sampling Environmental Sites for Legionellae [5 pages]
Also available as web page.
- Procedures for Collecting and Processing Environmental Samples
- Potential Sampling Sites in Healthcare Facilities
De-Contamination of Affected Water Systems
There are many options available for remediation of water systems contaminated with Legionella. Considerations include type of water system (e.g., cooling tower, potable water, hot tub), demonstrated effectiveness, cost, and ease of application. Consultation with an experienced Legionella contractor is recommended, as general guidelines are often difficult to apply to complex and varied water systems. For additional information about remediation, see:
- ASHRAE Guideline 12-2000: Minimizing the Risk of Legionellosis Associated with Building Water Systems 2000 (Also available from SPX Cooling Technologies and Baltimore Air Coil Company.)
This guideline provides information regarding the ecology of Legionella and guidance to minimize and remediate colonization in building water systems.
- ASHRAE Standard 188-2015: Legionellosis: Risk Management for Building Water Systems (ANSI approved)
This standard establishes minimum risk management requirements for building water systems to prevent legionellosis.
- Frequently Asked Questions on ASHRAE Standard 188-2015: Legionellosis: Risk Management for Building Water Systems
This webpage answers frequently asked questions about ASHRAE Standard 188, which outlines a legionellosis risk management program for facilities.
- Disinfection of Hot Tubs Contaminated with Legionella [2 pages]
This fact sheet contains best practices for how to remediate hot tubs.
See the "CDC can assist health departments in investigating a potential cluster of Legionnaires’ disease" section for specific details.Top of Page
- Page last reviewed: February 5, 2013
- Page last updated: August 17, 2015
- Content source: