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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

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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: American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. 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.)

Disinfection of Hot Tubs Contaminated with Legionella[2 pages]


Authority Over Cruise Ships


CDC Assistance

See the "CDC can assist health departments in investigating a potential cluster of Legionnaires’ disease" section for specific details.


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