Human Health Issues related to Avian Influenza in Canada

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Appendix A: Sample Avian Influenza (H7N3) Outbreak Case Definitions for Investigation of Human Cases Associated with Domestic Avian Influenza Outbreaks

[based on BC Avian Influenza (H7N3) Outbreak Case Definitions, 2004]

The following definitions were developed by the national Respiratory Infections Surveillance Committee (RISC) and the BC Centre for Disease Control to assist with the identification of human influenza A (H7) cases and infections associated with the avian influenza A (H7N3) poultry outbreak in Fraser Valley, British Columbia, which began in February 2004. It is expected that these definitions, which were last updated April 22, 2004, will be modified relative to specific information is obtained specific to the virus strain and the epidemiology and clinical presentation of cases. These sample case definitions are intended to serve as a starting point for jurisdictions dealing with an outbreak of avian influenza and planning an investigation of possible human cases which may arise from an outbreak in birds. Other jurisdictions, not directly affected by the outbreak, are encouraged to refer to the sections of the Canadian Pandemic Influenza Plan that correspond to the pandemic phase (e.g., Canadian Phase 1.0 or 2.0) as indicated by the epidemiological findings from the outbreak.

Suspect Case

An individual presenting with onset of two or more of conjunctivitis*and/or H7N3 related influenza-like illness (ILI) symptoms** occurring between 1 day after first exposure/ contact and 7 days after last exposure/ contact inclusive, to a potential source of avian influenzavirus*** in the <geographic area>, <P/T>. Symptoms should not be fully attributable to another known etiology.

*Conjunctivitis Symptoms:

• red eye, eyelid/ conjunctiva inflammation (swelling), tearful eye, itching eye, painful eye, burning eye, discharge from eye, or sensitivity to light.

^**H7N3 related ILI Symptoms:

• fever (if measured, greater than 38C), cough, rhinorrhea, sore throat, myalgia/arthralgia, or headache

***Potential source of avian influenza can be:

• infected or potentially infected poultry
• infected or potentially infected raw or under-cooked poultry products
• infected poultry manure
• contaminated surfaces
• contaminated vehicles, equipment, clothing and footwear at involved sites
• contaminated air space
• other infected or potentially infected animals (e.g., wild fowl, swine, etc.)
• individuals known to be infected

Confirmed Case

An individual who fulfills the criteria of a suspect case and has laboratory confirmation of influenza A (H7) virus in any specimen(s) from the eye (conjunctival swab), respiratory tract (nasal or nasopharyngeal swab or nasal wash) and/or serology by at least one of the following:

1) Virus isolation in cell culture

2) RT-PCR (confirmed by another RT-PCR test on a second specimen sample)

3) Evidence of sero-conversion from acute and convalescent sera, taken at a 2 week interval, with a four-fold rise in antibody titre.

Asymptomatic or Atypical Infection:

An individual who either has no clinical symptoms or has a clinical presentation unique from that of a suspect case yet has laboratory confirmation (i.e. as detailed above for a confirmed case) of an infection with influenza A (H7).

Notes:

• Swab or nasal wash samples not to be taken immediately after exposure (> 12 hours recommended) to avoid positive tests due to surface contamination of mucous membranes as opposed to infection of mucous membranes.
• When only convalescent sera are available, control sera can be used as a baseline to assess titre rise. Details on testing are to follow from the National Microbiology Laboratory (NML).
• Due to its higher reported sensitivity, microneutralization techniques are recommended over HI techniques. Specifics on use of microneutralization testing are to follow from the NML.
• Primary Case/Infection: Direct contact with infected or potentially infected poultry, material or poultry products.
• Secondary Case/Infection: Direct contact with an individual who is identified as a confirmed case, a suspect primary case or a person with asymptomatic/ atypical infection.

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