Definitions for the 2005-2006 season

FluWatch reports include data and information from four main sources: laboratory reports of positive influenza tests in Canada; sentinel physician reporting of influenza-like illness (ILI); provincial/territorial assessment of influenza activity based on various indicators, including laboratory surveillance, ILI reporting, school and work site absenteeism, and outbreaks; WHO and other international reports of influenza activity. The map shows influenza activity in the “influenza surveillance regions” † within each jurisdiction, as determined by the provincial/territorial epidemiologists.

ILI definitions for the 2005-2006 season

ILI in the general population: Acute onset of respiratory illness with fever and cough and with one or more of the following - sore throat, arthralgia, myalgia, or prostration which could be due to influenza virus. In children under 5, gastrointestinal symptoms may also be present. In patients under 5 or 65 and older, fever may not be prominent.

Definitions of ILI/Influenza outbreaks for the 2005-2006 season

Schools and work sites: greater than 10% absenteeism on any day most likely due to ILI

Residential institutions: two or more cases of ILI within a seven-day period, including at least one laboratory confirmed case. Institutional outbreaks should be reported within 24 hours of identification.

Influenza activity levels are defined as:
1 =	No activity reported
2 =	Sporadic:	sporadically occurring ILI and confirmed influenza* with NO outbreaks detected within the influenza surveillance region†
3 =	Localized:	sporadically occurring ILI and confirmed influenza* together with outbreaks of ILI in schools and worksites or laboratory confirmed influenza in residential institutions occurring in less than 50% of the influenza surveillance region(s)†
4 =	Widespread:	sporadically occurring ILI and confirmed influenza* together with outbreaks of ILI in schools and worksites or laboratory confirmed influenza in residential institutions occurring in greater than or equal to 50% of the influenza surveillance region(s)†
* confirmation of influenza within the surveillance region at any time within the prior four weeks † sub-regions within the province or territory as defined by the provincial/territorial epidemiologist We would like to thank all physicians, nurse practitioners and their staff who are participating in this year’s influenza surveillance program.