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Increased influenza activity reported in the West and in Ontario

During week 48, localized influenza activity was reported in regions of Alberta and Ontario. Sporadic influenza activity was reported in a few regions (in the West, Ontario and Quebec), however, the majority of regions in the rest of the country reported no activity (see map). In week 48, 35 (1.8%) of the 1,956 specimens tested for influenza virus were positive and all were influenza A (see table). The majority (97%) of influenza detections to date this season were influenza A viruses. The ILI consultation rate rose from the previous week to a rate increased from 11 per 1,000 patient visit in week 47 to 30 per 1,000 patient visits in week 48, which is within the expected range for this week (see ILI graph). During weeks 47 and 48, the sentinel response rate was 73%. During week 48, 1 new outbreak of ILI was reported in a school in Alberta.

Antigenic Characterization:
The National Microbiology Laboratory (NML) has characterized 20 influenza viruses for the 2006-2007 influenza season: 7 A/Wisconsin/67/2005(H3N2)-like viruses (from Ontario) and 13 A/New Caledonia/20/99(H1N1)-like viruses (from Alberta and British Columbia) (see pie chart). Both strains are included in the composition of the 2006-2007 Canadian influenza vaccine.

Antiviral Resistance:
Since the start of the season, the NML has tested 15 influenza A isolates (9 H1N1, 6 H3N2) for amantadine resistance of which 2 (13.3% - all H3N2) were resistant (see recommendation below). None of the 8 influenza A isolates (7 H1N1, 1 H3N2) tested were found to be resistant to oseltamivir.

Influenza-associated Pediatric Hospitalizations:
One new laboratory-confirmed influenza-associated paediatric hospitalization from Ontario was reported through the Immunization Monitoring Program Active (IMPACT) network. The case was admitted in week 46 due to influenza B and is the third case that has been reported to IMPACT since the start of this influenza season.

International:
CDC: During week 47, a low level of influenza activity was reported in the United States. The proportion of patient visits to sentinel providers for influenza-like illness (ILI) and the proportion of deaths attributed to pneumonia and influenza were below baseline levels. Of the 1,823 specimens tested for influenza virus in week 47, 67 (3.7%) were positive. Since October 1, 2006 CDC has antigenically characterized 23 influenza viruses: 6 A/New Caledonia/20/99-like, 6 B/Victoria lineage, and 11 B/Yamagata lineage. It is too early in the influenza season to determine which influenza viruses will predominate or how well the vaccine and circulating strains will match.

• CDC

WHO: During weeks 45-46, overall influenza activity worldwide remained low.

• WHO

EISS: During week 48 clinical influenza activity remained at baseline levels in Europe. Of the 447 respiratory specimens collected by sentinel physicians 9 (2.0%) were positive for influenza virus and the consultation rates for ILI and/or ARI have been at baseline levels across the whole of Europe. The proportion of influenza A specimens among the total number of positive sentinel specimens remained high (90%).

• 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 26, 2006 to December 2, 2006 (Week 48)
	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=20]

{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]