Laboratory-Confirmed Influenza

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(including novel influenza subtypes)
Nationally notifiable since 2000

1.0 National Notification

Only confirmed cases of disease should be notified.

2.0 Type of Surveillance

Aggregate weekly influenza detections reporting by the Respiratory Virus Detection Surveillance System (RVDSS)

Case-by-case notification of laboratory-based epidemiologic information by the RVDSS

Enhanced, active reporting of aggregate and case-by-case data by paediatric tertiary care hospitals involved in the Immunization Monitoring Program, Active (IMPACT)

3.0 Case Classification

3.1 Confirmed case

Clinical illness with laboratory confirmation of infection:

• isolation of influenza virus from an appropriate clinical specimen
  OR
• demonstration of influenza virus antigen in an appropriate clinical specimen
  OR
• significant rise (e.g. fourfold or greater) in influenza IgG titre between acute and convalescent sera
  OR
• detection of influenza RNA

4.0 Laboratory Comments

5.0 Clinical Evidence

Clinical illness defined as influenza-like illness (ILI) is characterized as follows: acute onset of respiratory illness with fever and cough and with one or more of the following:

• sore throat
• arthralgia
• myalgia
• prostration that could be due to influenza virus.

In children under 5, gastrointestinal symptoms may also be present. In patients under 5, or 65 and older, fever may not be prominent. Note: Illness associated with novel influenza viruses may present with other symptoms.

6.0 ICD Code(s)

6.1 ICD-10 Code(s)

J10 Influenza due to identified influenza virus

• J10.0 Influenza with pneumonia, influenza virus identified
• J10.1 Influenza with other respiratory manifestations, influenza virus identified
• J10.8 Influenza with other manifestations, influenza virus identified

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

487 Influenza

• 487.0 Influenza with pneumonia
• 487.1 Influenza with other respiratory manifestations
• 487.8 Influenza with other manifestations

7.0 Type of International Reporting

Enhanced reporting to WHO for any case of human influenza caused by a novel influenza virus or in the event of a public health emergency is required under the International Health Regulations (2005).

8.0 Comments

In addition to the symptoms of ILI noted above, severe ILI may also include complications such as pneumonia, acute respiratory distress syndrome (ARDS), encephalitis or other severe and lifethreatening complications.

9.0 References

10.0 Previous Case Definitions

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

Date of Last Revision/Review:

May 2008