ARCHIVED - Legionellosis


Nationally notifiable since 1986

1.0 National Notification

Only confirmed cases of disease should be notified.

2.0 Type of Surveillance

Routine case-by-case notification to the federal level

3.0 Case Classification

3.1 Confirmed case

Clinical illness (see section 5.0) with laboratory confirmation of infection:

  • isolation of Legionella species or detection of the antigen from respiratory secretions, lung tissue, pleural fluid or other normally sterile fluids
  • a significant (e.g. fourfold or greater) rise in Legionella species IgG titre between acute and convalescent sera
  • IgG titre > 1:128 against Legionella species
  • demonstration of L. pneumophila antigen in urine (see section 4.0)

3.2 Probable case

Clinical illness with demonstration of Legionella species DNA

4.0 Laboratory Comments

Jurisdictions should use a validated antigen detection test, and test interpretation must be in accordance with the manufacturer’s instructions.

Most laboratories use culture with biochemical confirmation in conjunction with antigen detection. A limited number of laboratories currently participate in College of American Pathologists (CAP) and Clinical Microbiology Proficiency Testing (CMPT) proficiency testing programs.

Currently very few laboratories use NAT. A proficiency testing program for NAT is indicated.

5.0 Clinical Evidence

Legionellosis comprises two distinct illnesses: Legionnaires’ disease, characterized by fever, myalgia, cough and pneumonia, and Pontiac fever, a milder illness without pneumonia.

6.0 ICD Code(s)

6.1 ICD-10 Code(s)

Legionnaire’s Disease
Pontiac Fever

6.2 ICD-9/ICD-9CM Code(s)

Legionnaire’s Disease

7.0 Type of International Reporting

Notification in the event of a public health emergency is required under the International Health Regulations (2005).


Probable case definitions are provided as guidelines to assist with case finding and public health management, and are not for national notification purposes.

9.0 References

10.0 Previous Case Definitions

Canadian Communicable Disease Surveillance System: disease-specific case definitions and surveillance methods. Can Dis Wkly Rep 1991;17(S3).

Case definitions for diseases under national surveillance. CCDR 2000;26(S3).

Date of Last Revision/Review:

May 2008

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