Global Influenza Programme
We provide Member States with strategic guidance, technical support and coordination of activities essential to make their health systems better prepared against seasonal, zoonotic and pandemic influenza threats to populations and individuals.
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WHO surveillance case definitions for ILI and SARI

As of January 2014

The WHO global influenza surveillance standards define the surveillance case definitions for influenza-like illness (ILI) and severe acute respiratory infections (SARI).

Key messages when using the case definitions:

  • Influenza infection causes a clinical syndrome not easily distinguished from other respiratory infections.
  • The case definitions for ILI and SARI are not necessarily intended to capture all cases but to describe trends over time.
  • Using one common case definition globally will allow national health authorities to interpret their data in an international context.

ILI case definition

An acute respiratory infection with:

  • measured fever of ≥ 38 C°
  • and cough;
  • with onset within the last 10 days.

SARI case definition

An acute respiratory infection with:

  • history of fever or measured fever of ≥ 38 C°
  • and cough;
  • with onset within the last 10 days.
  • and requires hospitalization.

Related

Global epidemiological surveillance standards for influenza
Featured publication | 9 August 2013

Global epidemiological surveillance standards for influenza
This document proposes surveillance objectives and describes global standards for a minimal basic respiratory disease surveillance system for the monitoring of influenza.
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Revision of clinical case definitions: influenza-like illness and severe acute respiratory infectionDownload (pdf, 449 KB)