February 8, 2009 to February 14, 2009 (Week 6)

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Overall influenza activity in Canada continues to increase; both influenza A and B virus detections increasing
During week 06, influenza activity in Canada continued to increase: 17 regions reported localized activity (in BC, AB, MB, ON, QC, NB & NS), 25 regions sporadic and 12 regions reported no activity (see map). The proportion of tests that were positive for influenza continued to increase (percentage positive = 14.1%; 745/5,280) (see table). Although the majority of influenza virus detections to date this season were influenza A viruses (57% or 1,425/2,491) detections for influenza B viruses are also increasing (see graph). This week, the ILI consultation rate increased to 34 ILI consultations per 1,000 patient visits (see ILI graph) which is within the expected range. The sentinel response rate was 61%. In week 06, 19 new influenza outbreaks were reported: 9 in LTCFs (BC, AB, & MB) and 10 in schools (BC, AB, MB, NS & NB).

Antigenic Characterization:
Since 1 September 2008, the NML has antigenically characterized 317 influenza viruses: 79 influenza A/Brisbane/59/2007(H1N1)-like (from BC, AB, SK, ON, QC, NS & PEI), 39 influenza A/Brisbane/10/2007(H3N2)-like (from BC, AB, SK, ON, QC, PEI & NL), 6 influenza B/Florida/4/2006-like (from AB, ON & QC) and 193 B/Malaysia/2506/2004-like (in all provinces except the Territories). 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).

*** The WHO recommends that the vaccines to be used in the 2009-2010 season (northern hemisphere) contain the following: an A/Brisbane/59/2007 (H1N1)-like virus; an A/Brisbane/10/2007 (H3N2)-like virus; and a B/Brisbane/60/2008-like virus.

• WHO

Antiviral Resistance:

Results from the NML:

Since the start of the season, the NML has tested 155 influenza A isolates (86 H1N1 and 69 H3N2) for amantadine resistance. All of the H1N1 isolates were susceptible; however all of the H3N2 isolates were resistant to amantadine (resistance = 100% or 69/69). The resistant isolates were from BC, AB, SK, ON, QC, PEI, NL & NT.

The NML has also tested 252 influenza isolates (73 A/H1N1, 31 A/H3N2 & 148 B) for oseltamivir (Tamiflu) resistance. All of the A/H3N2 and B isolates were sensitive; however all of the A/H1N1 isolates were resistant to oseltamivir due to the H274Y mutation (resistance = 100% or 73/73). The resistant isolates were from BC, AB, SK, ON, QC, NS & PEI.

All 245 influenza isolates (66 A/H1N1, 31 A/H3N2 & 148 B) tested for zanamivir resistance to date were sensitive to zanamivir.

Oseltamivir resistance findings from Provincial laboratories:

To date this season, 88 influenza isolates in BC have been sub-typed as A/H1 and were assessed genotypically for oseltamivir resistance using an SNP assay. Eighty isolates tested positive for the H274Y mutation (resistance = 100% or 80/80), with the other 8 specimens still pending confirmatory testing.

Influenza-associated Paediatric Hospitalizations:
In week 06, 23 laboratory-confirmed influenza-associated paediatric hospitalizations were reported through the Immunization Monitoring Program Active (IMPACT) network. The cases were from BC, ON & QC and 78% were due to influenza A. To date, 119 hospitalizations have been reported of which 73% (87/119) have been due to influenza A. The proportion of cases to date by age group are as follows: 22% were 0-5 month olds; 16% were 6-23 month olds; 14% were 2-4 year-olds; 14% were 5-9 year-olds; and 34% were 10-16 year-olds. The distribution of cases to date by province are as follows: 8% from BC, 9% from AB, 1% from SK, 59% from ON, 21% from QC & 2% from NS.

International:

CDC: During week 05, influenza activity continued to increase in the United States; 1,154 (20.6%) specimens tested  positive for influenza, of which 78% were influenza A and 22% were influenza B. Testing for antiviral resistance indicated that of the influenza virus A/H1N1 tested, 98.3% were resistant to oseltamivir and 0.8% resistant to amantadine. Of the influenza A/H3N2 viruses tested for resistance, 100% were resistant to amantadine. All tested viruses remain sensitive to zanamivir. One influenza-associated pediatric death was reported during week 05.

• CDC

EISS: Influenza activity continues to increase in central and eastern Europe while continuing to decrease in western Europe. Influenza A(H3N2) continues to be the dominant influenza virus circulating in Europe. Of the 198 A(H3N2) isolates that were tested for adamantanes susceptibility, 198 (100%) were resistant. Of the 146 A(H1N1) virus isolates tested for resistance against neuraminidase inhibitors, 143 (98%) were resistant to oseltamivir, but all were sensitive to zanamivir.

• EISS

Human Avian Influenza: Since 14 February 2009, the WHO has reported a new case of human H5N1 avian influenza infection from Viet Nam.

• 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: February 8, 2009 to February 14, 2009				Season to Date: August 24, 2008 to February 14, 2009
	Total # Influenza Tests	# of Positive Tests			Total # Influenza Tests	# of Positive Tests
		Influenza A	Influenza B	Total		Influenza A	Influenza B	Total
NL	56	6	1	7	355	14	4	18
PE	19	0	2	2	128	8	6	14
NS	60	4	2	6	523	18	13	31
NB	75	12	7	19	561	39	25	64
QC	2091	202	144	346	14865	571	242	813
ON	1555	68	135	203	16840	282	586	868
MB	75	3	0	3	1282	4	4	8
SK	243	5	9	14	2721	24	22	46
AB	965	80	11	91	12497	257	109	366
BC	141	42	12	54	1441	208	55	263
Canada	5280	422	323	745	51213	1425	1066	2491

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, February 8, 2009 to February 14, 2009
	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=317]

{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 2007/08 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