Influenza activity in Canada remains low; lab detections and ILI consultation rates continue to increase from previous weeks
During week 48, influenza activity in Canada remained low with the majority of the influenza surveillance regions reporting no activity. Thirteen regions ( in BC, AB, ON & QC ) reported sporadic influenza activity this week (see map). Eighteen specimens tested positive for influenza in Canada this week (percentage positive =1.0%; 18/1,818) (see table). In week 48, the ILI consultation rate increased to 18 ILI consultations per 1,000 patient visits (see ILI graph), and is within the expected range for this week. The sentinel response rate was at 62%. No new influenza outbreaks were reported in week 48.

Antigenic Characterization & Antiviral Resistance:
Since 1 September 2008, the NML has antigenically characterized six influenza viruses: one influenza A/Brisbane/59/2007(H1N1)-like (from NS), two influenza A/Brisbane/10/2007(H3N2)-like (from BC & ON), two influenza B/Florida/4/2006-like (from ON and AB) and one B/Malaysia/2506/2004-like (from AB). A/Brisbane/59/2007(H1N1), A/Brisbane/10/2007(H3N2) and B/Florida/4/2006 are the influenza A and influenza B components recommended for the 2008-09 influenza vaccine. B/Malaysia/2506/2004 was the influenza B component for the 2007-2008 season vaccine (see pie chart).

Antiviral Resistance:
Since the start of the season, the NML has tested 2 influenza A isolates (1 H1N1 and 1 H3N2) for amantadine resistance and found that the H3N2 isolate was resistant to amantadine and the H1N1 isolate was susceptible; resulting in 50% (1/2) resistance among all influenza A isolates tested.

The NML has also tested 5 influenza isolates (1 A/H1N1, 1 A/H3N2 & 3 B) for oseltamivir (Tamiflu) resistance and found that the H1N1 isolate tested was resistant to oseltamivir due to the H274Y mutation whereas the H3N2 and B isolates were susceptible; resulting in 20% (1/5) resistance among all influenza isolates tested.

All 5 influenza isolates (1 A/H1N1, 1 A/H3N2 & 3 B) tested for zanamivir resistance to date were sensitive to zanamivir.

Influenza-associated Paediatric Hospitalizations:
No laboratory-confirmed influenza-associated paediatric hospitalizations have been reported through the Immunization Monitoring Program Active (IMPACT) network for the 2008-09 season.

International:

CDC: During week 47, a low level of influenza activity was reported in the United States. One state (Hawaii) reported local influenza activity however the majority reported either no activity or sporadic activity. Of the 2,080 specimens tested this week for influenza viruses, 52 (2.5%) were positive. Since 1 October 2008, the CDC has antigenically characterized 21 influenza viruses: 20 influenza A(H1) (all A/Brisbane/59/2007-like) and 1 influenza B (B/Florida/04/2006-like). Since 1 October, 2008, 34 influenza viruses (21 A(H1N1), 5 A (H3N2), and 8 B) have been tested for resistance to neuraminidase inhibitors. Of the A(H1N1) viruses tested, 95% (20/21) were resistant to oseltamivir however all were sensitive to zanamivir. All of the A(H3N2) and B viruses tested were sensitive to both oseltamivir and zanamivir. The CDC tested 10 influenza A viruses (6 H1, 4 H3) for amantadine resistance: all of the H1N1 viruses were sensitive to amantadine however all the H3N2 viruses were resistant.

• CDC

EISS: Influenza activity in Europe continues to be low, although slowly increasing activity in some countries. The majority (92%) of virus detections have been influenza A and 90% of those subtyped were shown to be A/H3. Limited data are available on antiviral resistance: 95% (18/19) of the influenza A(H1N1) viruses analysed to date are resistant to oseltamivir. These represent very early-season isolates and therefore it is too early to comment on the antiviral resistance pattern for Europe as a whole.

• EISS

Human Avian Influenza: No new cases of human H5N1 avian influenza infection have been reported by the WHO since 10 September 2008.

• WHO

Fightflu.ca : Canada's provinces and territories and the Public Health Agency of Canada launched fightflu.ca, a pan-Canadian web portal designed to provide Canadians with one-stop access to information about influenza and ways to limit its spread. The portal also provides fact sheets on influenza and tips for avoiding infection in over 10 languages.

• www.fightflu.ca

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Total number of influenza tests performed and number of positive tests by province/territory of testing laboratory, Canada, 2008-2009

Province of reporting laboratories	Report Period: November 23, 2008 to November 29, 2008				Season to Date: August 24, 2008 to November 29, 2008
	Total # Influenza Tests	# of Positive Tests			Total # Influenza Tests	# of Positive Tests
		Influenza A	Influenza B	Total		Influenza A	Influenza B	Total
NL	7	0	0	0	88	0	0	0
PE	4	0	0	0	30	0	0	0
NS	12	0	0	0	155	1	0	1
NB	9	0	0	0	75	0	0	0
QC	468	5	0	5	3949	32	2	34
ON	636	0	0	0	5195	4	2	6
MB	55	0	0	0	598	0	0	0
SK	88	0	0	0	910	0	0	0
AB	488	0	7	7	5098	2	18	20
BC	51	6	0	6	402	9	1	10
Canada	1818	11	7	18	16500	48	23	71

 

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-eng.php>

Number of influenza surveillance regions† reporting widespread or localized influenza activity, Canada, by report week, 2008-2009 (N=54)

† 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 23, 2008 to November 28, 2008 (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, 2008-2009

Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2008-2009

Influenza strain characterization, Canada, cumulative, 2008-2009 influenza season by the Respiratory Viruses Section at the National Microbiology Laboratory
[N=6]

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

NACI recommends that the trivalent vaccine for the 2008-2009 season in Canada contain A/Brisbane/59/2007 (H1N1)-like virus; an A/Brisbane/10/2007 (H3N2)-like virus; and a B/Florida/4/2006-like virus.

Influenza-like illness (ILI) consultation rates, Canada, by report week,
2008-2009 compared to 1996/97 through to 2006/07 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, 2008-2009

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

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Definitions for the 2008-2009 season