Influenza (Influenza A and B virus)

Clinical criteria
Any person with the following clinical syndrome:

Influenza-like illness (ILI)
- Sudden onset of symptoms
AND
- at least one of the following four systemic symptoms:

- Fever or feverishness
- Malaise
- Headache
- Myalgia

AND
- at least one of the following three respiratory symptoms:

- Cough
- Sore throat
- Shortness of breath

Laboratory criteria
At least one the following four:
- Isolation of influenza virus from a clinical specimen
- Detection of influenza virus nucleic acid in a clinical specimen
- Identification of influenza virus antigen by DFA test in a clinical specimen
- Influenza specific antibody response (four fold or greater rise)
Subtyping of the influenza isolate should be performed, if possible

Epidemiological criteria
An epidemiological link by human to human transmission

Case classification
A. Possible case
Any person meeting the clinical criteria (ILI)
B. Probable case
Any person meeting the clinical criteria (ILI) and with an epidemiological link
C. Confirmed case
Any person meeting the clinical (ILI) and the laboratory criteria 

Current as of: 22 January 2019