Influenza - Clinical and laboratory diagnosis criteria

CLINICAL

Clinical diagnoses are provided by the South Australian participants of the Royal Australian College of General Practitioner’s Australian Sentinel Practice Network (ASPREN). The ASPREN clinical definition for an influenza-like illness is a disease characterised by:

SIX of the following criteria:

• sudden onset (within 12 hours)
• cough
• rigours or chills
• fever
• prostration and weakness
• myalgia, widespread aches and pains
• no significant respiratory physical signs other than redness of nasal mucous membranes and throat
• influenza in close contacts.

OR 

• during an influenza epidemic, FOUR of the above criteria.

LABORATORY DIAGNOSIS

A laboratory diagnosis of influenza requires a viral culture, a virus antigen detection or a four-fold antibody titre rise between paired specimens of sera.