Case definitions

The table below outlines the case definitions used by the surveillance networks in EuroFlu.
For a discussion of the different case definitions used in Europe, please see: Aguilera JF et al. Heterogeneous case definitions used for the surveillance of influenza in Europe. European Journal of Epidemiology 2003: 18(8): 733-736.

Surveillance networks Influenza-like illness Acute respiratory infection Belgium Sudden onset of fever, with respiratory symptoms and systemic symptoms Common cold, (rhino-)pharyngitis, tonsilitis, sinusitis, acute otitis media, laryngitis, (laryngo-)tracheitis, bronchitis, bronchiolotis, (broncho)pneumonia. Czech Republic No case definition Cyprus Sudden onset of fever (38.5°C) of at least 2 days duration, symptoms from the upper respiratory system, weakness, muscular pains, and headache. Denmark Sudden onset of disease with fever, myalgia and symptoms of respiratory infection England No case definition Estonia Clinical picture compatible with influenza, e.g. sudden onset of disease, cough, fever > 38°C, muscular pain and/or headache. France Sudden onset of respiratory symptoms with infection context (fever, headaches), in the absence of other diagnosis Germany Acute pharyngitis, acute bronchitis or pneumonia, with or without fever Greece Acute onset of illness, cough, fever >38ºC, muscle ache and/or headache. Ireland Sudden onset of symptoms with a temperature of 38°C or more in the absence of any other disease with at least 2 of the following: headache, myalgia, sore throat, dry cough Italy Sudden onset of symptoms, with temperature >38°C, plus at least 1 systemic symptom and at least 1 respiratory symptom Latvia Every illness characterized by sudden onset of fever (>38°C) with respiratory symptoms (dry cough and sore throat), headache and/or myalgia Lithuania Sudden onset of fever (> 38°C ), cough, myalgia and/or headache. Sudden onset of respiratory symptoms rhino-pharyngitis, pharyngitis, sinusitis, tonsilitis, laryngitis, tracheitis, epiglottitis included. Luxembourg Sudden onset of fever (> or equal to 38°C), myalgia and respiratory symptoms (e.g. cough or pharyngitis). No case definition Malta Fever (>38°C) with cough and headache and/or muscular pain The Netherlands Pel criteria 1 Northern Ireland An acute respiratory illness accompanied by variable fever and myalgia Norway A patient with clear general symptoms, primarily acute fever >38°C, headache, muscle ache, and in addition a dry cough Poland No case definition Portugal ICHPPC-2-D definition2 Romania Every illness characterized by sudden onset, fever, myalgia and respiratory symptoms (cough, coryza). Common cold, rhinitis, rhino-pharyngitis, tonsilitis, sinusitis, otitis media, laryngitis, tracheitis, bronchitis, bronchiolotis, pneumonia and broncho-pneumonia. Scotland No case definition No case definition Slovak Republic Sudden onset and fever with (1) at least 1 respiratory symptoms; cough, rhinitis, sore throat, and (2) at least 1 general symptoms: headache, joint ache, chills, malaise Slovenia Sudden onset of fever (>38°C) with general weakness, muscle and joint pain, dry cough and symptoms of upper respiratory tract affection No case definition Spain ICHPPC-2-D case definition2 Sweden No case definition Switzerland Respiratory illness with fever >38°C, myalgia, general pain, chills, anorexia. (optional symptoms are: cough, rhinitis and arthralgia) Wales Upper respiratory tract symptoms, fever, chills, myalgia, cough

¹: Pel criteria An acute onset (i.e. at most a prodromal stage of three to four days), accompanied by a rise in rectal temperature of >38°C, and at least 1 of the following symptoms: cough, coryza, sore throat, frontal headache, retrosternal pain, myalgia.


²: International Classification of Health Problems in Primary Care
ILI: at least one of the following characteristics:

1. Influenza virus culture positive or serological evidence of influenza virus infection
2. Context of influenza epidemic, plus 4 of the criteria in 3.
3. 6 of the following criteria: sudden onset (within 12 hours), cough, fever, chills, prostration and weakness, myalgia or general pain, rhinitis, pharyngitis, contact with a case.