National case definition: Invasive group A streptococcal disease

Date of last revision: May 2008
Date of last review: May 2008

National reporting

Only confirmed cases of disease should be notified.

Type of surveillance

Routine case-by-case notification to the federal level.

Enhanced case-by-case reporting to International Circumpolar Surveillance in participating Northern regions.

Case classification

Confirmed case

Laboratory confirmation of infection with or without clinical evidence of invasive disease:

  • isolation of group A streptococcus (Streptococcus pyogenes) from a normally sterile site (blood, CSF, pleural fluid, pericardial fluid, peritoneal fluid, deep tissue specimen taken during surgery [e.g. muscle collected during debridement for necrotizing fasciitis], bone or joint fluid excluding the middle ear and superficial wound aspirates [e.g. skin and soft tissue abscesses]).

Probable case

Clinical evidence of invasive disease (see Clinical evidence section) in the absence of another identified aetiology and with non-confirmatory laboratory evidence of infection:

  • isolation of group A streptococcus from a non-sterile site
  • or
  • positive group A streptococcus antigen detection

Clinical evidence

Clinical evidence of invasive disease may be manifested as one or more of several conditions:

  • streptococcal toxic shock syndrome, which is characterized by hypotension (systolic blood pressure ≤ 90 mm Hg in an adult and < 5 percentile for age for children) and at least two of the following signs:
  • renal impairment (creatinine level ≥ 177 μmol/L for adults)
  • coagulopathy (platelet count ≤ 100,000/mm3 or disseminated intravascular coagulation)
  • liver function abnormality (SGOT, SGPT, or total bilirubin ≥ 2x upper limit of normal)
  • adult respiratory distress syndrome
  • generalized erythematous macular rash that may desquamate
  • soft-tissue necrosis, including necrotizing fasciitis, myositis or gangrene
  • meningitis

ICD code(s)

  • ICD-10 code(s)
    • A40.0 Septicaemia due to group A streptococcus
    • A49.1 Streptococcal infection, unspecified
    • B95.0 Group A Streptococcus as the cause of diseases classified elsewhere, e.g.:
      • A48.3 Toxic shock syndrome
      • O85 Puerperal sepsis
      • M72.6 Necrotizing fasciitis
      • M00 Pyogenic arthritis
    • G00.2 Streptococcal meningitis
  • ICD-9/ICD-9CM code(s)
    • 038.0 Septicaemia due to group A streptococcus
    • 041.01 Group A Streptococcal infection of unspecified site and in conditions classified elsewhere, e.g.:
      • 040.82 Toxic shock syndrome
      • 670 Major puerperal infection
      • 728.86 Necrotizing fasciitis
      • 711.0 Pyogenic arthritis
    • 320.2 Streptococcal meningitis


Pneumonia with isolation of group A streptococcus (GAS) from a sterile site or from a bronchoalveolar lavage (BAL) when no other cause has been identified, should be regarded as a form of invasive disease for the purposes of public health management; however, as BAL does not provide a sterile site specimen, the latter would not meet the national case definition and would not be notifiable.

The case definitions for invasive group A streptococcal disease provided in this document are for surveillance purposes. Probable case definitions are provided as guidelines to assist with case finding and public health management, and are not for national notification purposes. Definitions of cases (sporadic, index, subsequent, severe), close contacts and organization-based outbreaks for the purposes of public health management are provided in the national Guidelines for the Prevention and Control of Invasive Group A Streptococcal Disease (


Public Health Agency of Canada. Guidelines for the prevention and control of invasive group A streptococcal disease. CCDR 2006;32S2:1-26.

Previous case definitions

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

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