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Localized influenza activity in Alberta and Ontario; no activity in the rest of the country

During week 49, localized influenza activity was reported in all regions of Alberta and in one region of Ontario. Sporadic influenza activity was reported in several regions (in the West, Ontario and Quebec) while the rest of the country reported no activity (see map). In week 49, 93 (4%) of the 2,302 specimens tested for influenza virus were positive and all but 2 were influenza A (see table). Most (98%) of the influenza detections this season have been influenza A. The ILI consultation rate decreased from 30 per 1,000 patient visits in week 48 to 25 per 1,000 patient visits in week 49, which is within the expected range for this week (see ILI graph). During week 49, the sentinel response rate was 75%. Eleven new outbreaks of ILI were reported in schools in Alberta this week.

Note that over the last several weeks, the percent positive for Respiratory Syncytial Virus (RSV) detections has continued to increase from 7.8% in week 44 to 23.9% in week 49.

Antigenic Characterization:
The National Microbiology Laboratory (NML) has characterized 33 influenza viruses for the 2006-2007 influenza season: 19 (58%) A/Wisconsin/67/05(H3N2)-like viruses (from Ontario), 13 (39%) A/New Caledonia/20/99(H1N1)-like viruses (from Alberta and British Columbia), and one (3%) B/Malaysia/2506/04-like virus (from Ontario) (see pie chart). All three 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 20 influenza A isolates (12 H1N1, 8 H3N2) for amantadine resistance of which 3 (15% - all H3N2) were resistant (see recommendation below). None of the 20 influenza A isolates tested were found to be resistant to oseltamivir.

Influenza-associated Pediatric Hospitalizations:
No new laboratory-confirmed influenza-associated paediatric hospitalizations were reported through the Immunization Monitoring Program Active (IMPACT) network.

International:
CDC: During week 48, 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 2,441 specimens tested for influenza virus in week 48, 106 (4.3%) were positive. Twenty-nine (27.4%) of the positive specimens were influenza B viruses. Since October 1, 2006 CDC has antigenically characterized 27 influenza viruses: 10 A/New Caledonia/20/99-like, 6 B/Victoria lineage, and 11 B/Yamagata lineage.

• CDC

EISS: During week 49, clinical influenza activity remained at baseline levels in Europe, however, in the last three weeks, the number of laboratory confirmed cases have been increasing in Europe as a whole. So far this season, 92% of the virus isolates were influenza A. Detections of RSV have also been increasing in a number of European countries.

• 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, December 3, 2006 to December 9, 2006 (Week 49)
	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=33]

{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]