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Low levels of influenza activity in Canada overall

During week 46, localized influenza activity was reported in the Central Alberta and Central West region of Ontario. Sporadic influenza activity was reported in regions of British Columbia, Alberta, Saskatchewan and Ontario while the rest of the country reported no activity (see map). In week 46, 12 (0.8%) of the 1,519 specimens tested for influenza virus were positive (see table). The majority (96%) of influenza detections so far this season were influenza A viruses. The ILI consultation rate rose to a rate of 21 per 1,000 patient visits in week 46, which is within the expected range for this week (see ILI graph). The sentinel response rate was 55%. During week 46, 1 new influenza outbreak was reported in a school in Alberta.

Antigenic Characterization:
The National Microbiology Laboratory (NML) has characterized 10 influenza viruses for the 2006-2007 influenza season: 2 A/Wisconsin/67/2005(H3N2)-like viruses (from Ontario and Alberta) and 8 A/New Caledonia/20/99(H1N1)-like viruses (all from Alberta) (see pie chart). Both strains are included in the composition of the 2006-2007 Canadian influenza vaccine.

Antiviral Resistance:
The NML has tested 9 influenza A isolates for amantadine resistance this season and found that 2 influenza A/H3N2 isolates tested were resistant to amantadine. The other 7 isolates were influenza A/H1N1 which remain sensitive to amantadine. (see recommendation below)

Influenza-associated Pediatric Hospitalizations:
During week 46, no new laboratory-confirmed influenza-associated paediatric hospitalizations were reported through the Immunization Monitoring Program Active (IMPACT) network. One case has been reported to IMPACT since the start of this influenza season.

International:
CDC: During week 45, a low level of influenza activity was reported in the United States and the proportion of patient visits to sentinel providers for ILI and the proportion of deaths attributed to pneumonia and influenza were below baseline levels. Of the 1,764 specimens tested for influenza virus in week 45, 82 (4.6%) were positive. Since 1 October 2006, CDC has antigenically characterized 17 influenza viruses: 1 influenza A/New Caledonia/20/1999(H1N1)-like and 16 influenza B viruses (5 belonging to the B/Victoria lineage and 11 belonging to the B/Yamagata lineage). It is too early in the influenza season to determine which viruses will predominate or how well the vaccine and circulating strains will match.

• CDC

EISS: In week 46, clinical influenza activity was at baseline levels in Europe which is typical for this time of the year. Since the beginning of October, a total of 45 influenza A and 3 influenza B cases were reported. So far this season, 5 influenza viruses have been antigenically and/or genetically characterized: 1 was A/New Caledonia/20/1999(H1N1)-like; 3 were A/Wisconsin/67/2005(H3N2)-like; and 1 A/California/7/2004(H3N2)-like.

• EISS

Recommendation for the Use of Amantadine for Treatment and Prevention of Influenza
The Public Health Agency of Canada does not recommend the use of amantadine for treatment or prevention of influenza for the 2006-2007 season. This recommendation will be revisited if new information becomes available.

Total number of influenza tests performed and number of positive tests by province/territory of testing laboratory, Canada, 2006-2007

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, 2006-2007 (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, November 12, 2006 to November 18, 2006 (Week 46)
	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 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, 2006-2007

Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2006-2007

Influenza strain characterization, Canada, cumulative, 2006-2007 influenza season by the Respiratory Viruses Section at the National Microbiology Laboratory
[N=10]

{Strain characterization, number identified, per cent of total number}

NACI recommends that the trivalent vaccine for the 2006-2007 season in Canada contain A/New Caledonia/20/1999 (H1N1)-like, A/Wisconsin/67/2005 (H3N2)-like, and B/Malaysia/2506/2004-like virus antigens.

Influenza-like illness (ILI) consultation rates, Canada, by report week, 2006-2007 compared to 1996/97 through to 2005/06 seasons

Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons).

Number of New Outbreaks in Long Term Care Facilities, Canada, by Report Week, 2006-2007

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

Definitions for the 2006-2007 season

[FluWatch]