Definitions for the 2008-2009 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; influenza-associated pediatric hospitalizations; 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 2008-2009 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 2008-2009 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:	i.e. no laboratory-confirmed influenza detections during the past four weeks, however, sporadically occurring ILI may be reported
2 =	Sporadic:	sporadically occurring ILI and lab confirmed influenza* with NO outbreaks detected within the influenza surveillance region†
3 =	Localized:	sporadically occurring ILI and lab 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 lab 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 the Fluwatch surveillance partners who are participating in this year's influenza surveillance program.

Visual Example – Influenza Activity Levels

Legend:
	- laboratory detection(s)
	- Outbreak(s) of influenza or influenza-like-illness (ILI)

Step 1:
Were there any laboratory-confirmed influenza detections in the surveillance region within the last 4 weeks? YES	NO	Region : No activity
Step 2:
Were there any outbreaks of influenza or ILI in the surveillance region in the current week? YES	NO	Region : Sporadic
Step 3:
Are the outbreaks occurring in more than 50% of the surveillance region? YES	NO	Region : Localized
		Region : Widespread