Influenza activity in Canada remains low; lab detections and ILI consultation rates slightly increased from previous week
During week 46, influenza activity in Canada remained low with the majority of the influenza surveillance regions reporting no activity and only 8 regions (in BC, AB, ON & QC ) reported sporadic influenza activity (see map). Ten specimens tested positive for influenza in Canada this week (percentage positive = 0.7%; 10/1,479) (see table). In week 46, the ILI consultation rate increased to 13 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 57%. Fluctuations in ILI consultation rates are expected during periods of low influenza activity and low sentinel participation. No new influenza outbreaks were reported in week 46.

Antigenic Characterization & Antiviral Resistance:
No new strains characterizations have been reported by the National Microbiology Laboratory (NML) this week. However, since 1 September 2008, the NML has antigenically characterized five influenza viruses: one influenza A/Brisbane/10/2007(H3N2)-like (from BC), one influenza A/Brisbane/59/2007(H1N1)-like (from NS), two influenza B/Florida/4/2006-like (from ON and AB) and one B/Malaysia/2506/2004-like (from AB). A/Brisbane/10/2007(H3N2), A/Brisbane/59/2007(H1N1) 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:
No new antiviral resistance findings have been reported by the NML this week. However, 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.

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:

WHO: During the weeks 45 to 46, the level of overall influenza activity in the world remained low with sporadic activity observed in some countries.

• WHO

CDC: During week 45, 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 2,332 specimens tested this week for influenza viruses, 40 (1.7%) were positive. Since 1 October 2008, the CDC has antigenically characterized one influenza virus: B/Florida/04/2006-like. Since 1 October, 2008, 3 influenza viruses (1 A(H1N1), 1 A (H3N2), and 1 B) have been tested for resistance to neuraminidase inhibitors and all were sensitive to oseltamivir and zanamivir. A small number of isolates from specimens collected during September were tested for adamantane resistance; 3 influenza A viruses (1 H1N1 and 2 H3N2) were resistant to the adamantanes.

• CDC

EISS: Influenza activity in Europe continues to be low; however, an increasing number of countries reported sporadic influenza virus detections compared to previous weeks. The majority (89%) of virus detections have been influenza A and 83% of those subtyped were shown to be A/H3. Limited data are available on antiviral resistance: 92% (11/12) 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

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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 9, 2008 to November 15, 2008				Season to Date: August 24, 2008 to November 15, 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	64	0	0	0
PE	2	0	0	0	24	0	0	0
NS	13	0	0	0	126	1	0	1
NB	8	0	0	0	58	0	0	0
QC	356	3	1	4	3008	14	2	16
ON	536	3	0	3	4024	3	2	5
MB	47	0	0	0	481	0	0	0
SK	53	0	0	0	738	0	0	0
AB	419	0	2	2	4104	1	8	9
BC	38	1	0	1	317	2	0	2
Canada	1479	7	3	10	12944	21	12	33

 

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 9, 2008 to November 15, 2008 (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, 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=5]

{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