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Canadian Summary:
During week 08, influenza activity overall in Canada is increasing with widespread activity being reported in Saskatchewan and parts of southern British Columbia. Localized activity was reported in British Columbia, Alberta, Ontario, Quebec and Nova Scotia whereas the rest of the country reported sporadic or no activity (see map). So far this season, influenza activity in Canada is lower compared to the last two seasons.

Over the one week period, the Public Health Agency of Canada received 3193 reports of laboratory tests for influenza of which 383 (12%) were positive for influenza virus. Fifty-nine percent of the positive influenza detections were from the west (Saskatchewan, Alberta & British Columbia) and 26% were from Ontario. In the current season to date, a mix of influenza A (56%) and influenza B (44%) viruses have been detected in Canada (see table) whereas influenza A virus detections predominated in the previous two seasons. The ILI consultation rate was calculated as 22 per 1000 patient visits in week 08, which is below the expected range for this week (see ILI graph).. During week 08, 38 new outbreaks were reported: 15 were in LTCF's; 20 were in schools; 1 was in a hospital; and 2 were in other settings. To date this season, 57 LTCF outbreaks have been reported.

Antigenic Characterization:
Since the start of the 2005-2006 influenza season, the National Microbiology Laboratory (NML) has antigenically characterized 394 influenza viruses: 202 A/California/07/2004(H3N2)-like viruses; 7 A/New Caledonia/20/1999(H1N1)-like viruses; 136 B/Hong Kong/330/2001-like and 44 B/Malaysia/2506/2004-like viruses both belonging to the B/Victoria/2/1987 lineage; and 5 B/Shanghai/361/2002-like viruses belonging to the B/Yamagata/16/1988 lineage. The B/Malaysia/2506/2004-like strain is the WHO-recommended influenza B component for the Northern Hemisphere 2006-2007 influenza vaccine.
* The 2005-2006 season Canadian vaccine contains an A/New Caledonia/20/1999(H1N1)-like, an A/California/7/2004(H3N2)-like, and a B/Shanghai/361/2002-like virus strain.
Vaccine Match:
To date, 100% of the influenza A strains characterized by the NML have matched those included in the 2005-2006 Canadian vaccine. However, only 3% of the influenza B characterizations have matched the current vaccine strain. The remaining 97% of the influenza B strains characterized have been B/Hong Kong/330/2001-like and B/Malaysia/2506/2004-like viruses, which belong to a separate lineage of viruses not covered by this year's vaccine.

Influenza-associated Pediatric Hospitalizations:
During week 08, 15 new laboratory-confirmed influenza-associated hospitalizations were reported through the IMPACT (Immunization Monitoring Program ACTive) network. Since the start of this influenza season, 84 cases have been reported to IMPACT from 10 of the 12 pediatric hospitals. Since the start of the season, 1 influenza-associated pediatric death has been reported to IMPACT.

International:
CDC: During week 07, overall influenza activity increased in the United States with the majority of widespread and regional activity being reported in the eastern and central states. The proportion of patient visits to sentinel providers for ILI (2.8%) was above baseline levels and the proportion of deaths due to pneumonia and influenza (7.3%) was below baseline levels. Since 1 October 2005, the CDC has antigenically characterized 253 influenza viruses: 208 A(H3N2) viruses (168 were A/California/07/2004-like viruses and 40 showed reduced titers with antisera produced against A/California/07/2004-like viruses); 14 A(H1) viruses (12 were similar antigenically to the hemagglutinin protein of the A/New Caledonia/20/1999-like viruses and 2 showed reduced titers with antisera against A/New Caledonia/20/1999-like viruses); and 31 influenza B viruses (19 were B/Yamagata/16/1988-lineage viruses and 12 were B/Victoria/2/1987-lineage viruses). Of the 40 low-reacting A(H3N2) viruses, 14 were tested with antisera produced against A/Wisconsin/67/2005 and 10 were A/Wisconsin/67/2005-like and is the A/H3N2 component selected for the 2006/2007 Northern Hemisphere influenza vaccine.

• CDC

EISS: Clinical influenza activity in Europe has been moderate so far this season. In week 08, Lithuania reported a high intensity of clinical influenza activity associated with influenza B virus. Whilst clinical influenza activity is now declining in a number of countries (e.g. France), some countries have seen very little influenza activity so far this season (e.g. Hungary, Poland and Slovenia). Since the start of the season, more influenza B viruses (68%) have been reported than influenza A viruses (32%) for Europe as a whole.

• EISS

Human Avian Influenza:
Since 26 February 2006, the WHO reported 3 new human cases with the H5N1 avian influenza virus: 1 case was from Indonesia and resulted in death; and 2 cases were from China, both of whom are in critical condition.

• WHO

Antiviral Resistance
The Public Health Agency of Canada recommends recommends that health care providers in Canada not prescribe amantadine to treat and prevent influenza during the current flu season following testing showing viruses currently in circulation in Canada and the US are resistant to the drug.

Total number of influenza tests performed and number of positive tests by province/territory of testing laboratory, Canada, 2005-2006

Specimens from NT, YT, and NU are sent to reference laboratories in other provinces.

Note: Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.

Abbreviations: Newfoundland/Labrador (NL), Prince Edward Island (PE), New Brunswick (NB), Nova Scotia (NS), Quebec (QC), Ontario (ON), Manitoba (MB), Saskatchewan (SK), Alberta (AB), British Columbia (BC), Yukon (YT), Northwest Territories (NT), Nunavut (NU)

Respiratory virus laboratory detections in Canada, by geographic regions, are available weekly on the following website:
<http://www.phac-aspc.gc.ca/bid-bmi/dsd-dsm/rvdi-divr/index.html>

Number of influenza surveillance regions† reporting widespread or localized influenza activity, Canada, by report week, 2005-2006 (N=76)

† sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.

Influenza Activity Level by Provincial and Territorial Influenza Surveillance Regions, Canada, February 19, 2006 to February 25, 2006 (Week 8)
	No Data No Activity Sporadic Activity Localized Activity Widespread Activity
Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and outbreaks. Please refer to detailed definitions for the 2005-2006 season. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website. Select single maps by report week to get this updated information. <http://dsol-smed.phac-aspc.gc.ca/dsol-smed/fluwatch/fluwatch.phtml?lang=e> Click on the map to view provinces/territories and maps for other weeks.

Influenza tests reported and percentage of tests positive, Canada, by report week, 2005-2006

Percent positive influenza tests, compared to other respiratory viruses by reporting week, Canada, 2005-2006

Influenza strain characterization, Canada, cumulative, 2005-2006 influenza season by the Respiratory Viruses Section at the National Microbiology Laboratory
[N=394]

(Strain characterization, number identified, per cent of total number)

NACI recommends that the trivalent vaccine for the 2005-2006 season in Canada contain A/New Caledonia/20/99 (H1N1)-like, A/California/7/2004 (H3N2)-like, and B/Shanghai/361/2002-like virus antigens.

* The B/Shanghai/361/2002-like virus belongs to the B/Yamagata/16/88 lineage; the B/Hong Kong/330/01-like and B/Malaysia/2506/2004-like viruses belong to the B/Victoria/02/87 lineage and are not covered by this year's vaccine.

Influenza-like illness (ILI) reporting rates, Canada, by report week, 2005-2006 compared to 1996/97 through 2004/2005 seasons

Note: No data available for mean rate in previous years for weeks 21 to 39 (1996-1997 through 2002-2003 seasons).

Number of New Outbreaks in Long Term Care Facilities by Report Week, Canada, 2005-2006

Please note that the above graphs may change as late returns come in.

Definitions for the 2005-2006 season

[FluWatch]