case definitions - avian influenza

Case Definition

Avian Influenza
Ministry of Health Case Definition for Avian Influenza A (H5N1)

Current at March 2007

Aims

Appropriate clinical management and infection control practices.
Surveillance.
Reporting.

Application of these case definitions

These case definition apply to the current phase of pandemic alert (phase 3).
Probable and confirmed cases will be notified to WHO.
The case definitions are intended to standardise reporting. They do not provide complete descriptions of clinical disease.
The clinical spectrum of Highly Pathogenic Avian Influenza A H5N1 disease is broad. Clinicians should exercise their judgment for the treatment, care and triage of persons who may have H5N1 infection.
For additional information on laboratory testing refer to the National Laboratory Guidelines for Pandemic Influenza: Collection and handling of human specimens for laboratory diagnosis of influenza with pandemic potential.

Case Definitions

Under Investigation

Suspect case of Influenza A (H5N1)

Probable case of Influenza A (H5N1)

Confirmed case of Influenza A (H5N1)

Avian Influenze H5N1 affected areas

Under Investigation

A person who has been referred to the Public Health service for investigation of possible H5N1 infection.

Back to Case Definitions List

Suspect case of Influenza A (H5N1)

Person with acute lower respiratory tract illness of abrupt onset, characterised by:

fever (temperature >38 C) and
cough and/or
dyspnoea (difficult or laboured breathing).

AND, in the seven days prior to the onset of symptoms, one or more of the following:

having been in close contact (less then 1 metre) with a suspect, probable or confirmed case of influenza A (H5N1)
exposure to avian species or their remains, or to environments contaminated by their faeces in an area where H5N1 infection in animals or humans have been suspect or confirmed in the last month
consumption of raw or undercooked poultry products in an area where H5N1 infections in animals or humans have been suspected or confirmed in the last month
close contact with a confirmed H5N1 infected animal of a species other than avian
handling samples from persons or animals that are suspected of H5N1 infection
working in a laboratory that is handling samples from persons or animals that are suspected of H5N1 infection.

Back to Case Definitions List

Probable case of Influenza A (H5N1)

a person meeting the definition of a suspected case and
limited laboratory evidence for Influenza A (H5N1) (such as IFA+ using H5 monoclonal antibodies).

Back to Case Definitions List

Confirmed case of Influenza A (H5N1)

a person meeting the definition of a suspected case; and
laboratory testing demonstrates one or more of the following:
1. positive PCR for Influenza A (H5N1) or
2. positive viral culture for Influenza A (H5N1) or
3. immunofluorescence antibody (IFA) test positive using Influenza A/H5 monoclonal antibodies or
4. a four-fold rise in H-5 specific Ab titer.

Back to Case Definitions List

Avian Influenza H5N1 affected areas

A list of currently affected countries and territories is available on the OIE website (www.oie.int).

Note:
Individuals infected with H5N1 are considered to be infectious starting from one day prior to the onset of symptoms up to seven days after the onset of symptoms.

Laboratory investigations for Influenza A may also be undertaken on deceased individuals and in the context of targeted epidemiological studies.

Laboratory confirmed cases identified under these circumstances should also be reported.

Back to Case Definitions List

Document download

You can download this case definition in Word and PDF formats.
Draft Case Definition for Avian Influenza (Word, 37 KB)

Draft Case Definition for Avian Influenza A (H5N1) (PDF, 82 KB)

Related information

WHO case definition

Communicable Diseases

Page last updated November 2006