Influenza Surveillance

Surveillance is the foundation of all efforts to understand and control a pandemic. The monitoring of influenza disease patterns is essential for identification of high risk groups, planning of prevention and response activities for complications and for estimating the burden of disease in terms of health and economic impact. It is important to use standardized case definitions that enable comparisons between different areas within a country and also between countries. There are two case definitions used by the influenza surveillance system:

• Influenza-like illness (ILI) is defined (according to WHO criteria) as:
• Sudden onset of a fever over 38°C, AND
• Cough or sore throat, AND
• An absence of other diagnoses.
• Severe Acute Respiratory Infections (SARI):.
  For persons = 5 years the definition for SARI is adapted from the WHO protocol on rapid response:
• Sudden onset of fever over 38°C, AND
• Cough or sore throat, AND
• Shortness of breath or difficulty in breathing, AND
• Requiring hospital admission
For children <5 years old: definition is adapted from the program for Integrated Management of Childhood Illness (IMCI):
Any child <5 years old clinically suspected of having Pneumonia or Severe/very Severe Pneumonia and requiring hospital admission.



• Confirmed case of influenza is defined as any case with laboratory test results positive for influenza virus.