February 22, 2009 to February 28, 2009 (Week 8)

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Overall influenza activity in Canada similar to previous week; however more regions reporting widespread activity

During week 08, influenza activity in Canada remained similar overall to the previous week: 5 regions (in BC, MB, QC & NL) reported widespread activity, 14 regions localized (in BC, AB, ON, QC, NB & NS), 26 regions sporadic and 9 regions reported no activity (see map). The proportion of tests that were positive for influenza remained the same as the previous week (percentage positive = 17%; 1,017/5,965) (see table). Although the majority of influenza virus detections to date this season were influenza A viruses (57% or 2,527/4,433) detections for influenza B viruses are also high (see graph). This week, the ILI consultation rate declined to 28 ILI consultations per 1,000 patient visits (see ILI graph) which is within the expected range. The sentinel response rate was 55%. In week 08, 27 new influenza outbreaks were reported: 13 in LTCFs (BC, MB, ON, QC & NL), 1 in a hospital (in NL) and 13 in schools (BC, NB & NS).

Antigenic Characterization:

Since 1 September 2008, the NML has antigenically characterized 470 influenza viruses: 101 influenza A/Brisbane/59/2007(H1N1)-like (from BC, AB, SK, ON, QC, NS, NB & PEI), 63 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 300 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)

Antiviral Resistance:

Results from the NML:

Since the start of the season, the NML has tested 216 influenza A isolates (114 H1N1 and 102 H3N2) for amantadine resistance. All of the H1N1 isolates were susceptible; however all of the H3N2 isolates were resistant to amantadine (resistance = 100% or 102/102). The resistant isolates were from BC, AB, SK, ON, QC, NB, PEI, NL & NT.

The NML has also tested 376 influenza isolates (95 A/H1N1, 52 A/H3N2 & 229 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 95/95). The resistant isolates were from BC, AB, SK, ON, QC, NB, NS & PEI.

All 366 influenza isolates (85 A/H1N1, 52 A/H3N2 & 229 B) tested for zanamivir resistance to date were sensitive to zanamivir.

Oseltamivir resistance findings from Provincial laboratories:

To date this season, 119 influenza isolates in BC have been sub-typed as A/H1 and were assessed genotypically for oseltamivir resistance using an SNP assay. One hundred and seven isolates tested positive for the H274Y mutation (resistance = 100% or 107/107), with the other 12 specimens still pending confirmatory testing.

Influenza-associated Paediatric Hospitalizations:

In week 08, 51 laboratory-confirmed influenza-associated paediatric hospitalizations were reported through the Immunization Monitoring Program Active (IMPACT) network. The cases were from AB, SK, ON, QC, NS & NL and 65% were due to influenza A. To date, 205 hospitalizations have been reported of which 70% (143/205) have been due to influenza A. The proportion of cases to date by age group are as follows: 21% were 0-5 month olds; 17% were 6-23 month olds; 13% were 2-4 year-olds; 13% were 5-9 year-olds; and 36% were 10-16 year-olds. The distribution of cases to date by province are as follows: 5% from BC, 9% from AB, 1% from SK, 1% from MB, 51% from ON, 30% from QC, 2% from NS & 0.5% from NL.

International:

WHO: During the weeks 07 to 08, the level of overall influenza activity in the world continued to increase.

• WHO

CDC: During week 07, influenza activity increased slightly in the United States; 1,405 (24.6%) specimens tested  positive for influenza, of which 68% were influenza A and 32% were influenza B. Testing for antiviral resistance indicated that of the influenza virus A/H1N1 tested, 98.8% were resistant to oseltamivir and 0.6% resistant to amantadine. Of the influenza A/H3N2 viruses tested for resistance, 100% were resistant to amantadine. All tested viruses remain sensitive to zanamivir. To date this season, 17 influenza-associated pediatric deaths have been reported to the CDC (8 of which were reported in week 07). Bacterial co-infections were confirmed in 10 (58.8%) of the 17 children; Staphylococcus aureus was identified in 8 (80.0%) of the 10 children. An increase in the number of influenza-associated pediatric deaths with bacterial co-infections was first recognized during the 2006-07 influenza season.

• CDC

EISS: Influenza activity remained similar to the previous week in Europe; however activity continued to decline in western and central Europe. Influenza A(H3N2) continues to be the dominant influenza virus circulating in Europe however the proportion of influenza B detections per week continues to show a rising trend, with an increasing number of countries reporting influenza B as the dominant or co-dominant virus type. Of the 198 A(H3N2) isolates that were tested for adamantanes susceptibility, 198 (100%) were resistant. Of the 153 A(H1N1) virus isolates tested for resistance against neuraminidase inhibitors, 150 (98%) were resistant to oseltamivir, but all were sensitive to zanamivir.

• EISS

Human Avian Influenza:Since 28 February 2009, the WHO reported a new case of human H5N1 avian influenza infection in Egypt.

• 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 22, 2009 to February 28, 2009				Season to Date: August 24, 2008 to February 28, 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	11	0	11	455	38	5	43
PE	12	2	0	2	151	12	6	18
NS	47	3	7	10	629	24	25	49
NB	162	30	7	37	810	92	47	139
QC	2377	312	245	557	19597	1167	689	1856
ON	1601	81	135	216	19861	420	867	1287
MB	114	7	0	7	1465	15	4	19
SK	287	14	9	23	3241	44	39	83
AB	1121	66	8	74	14606	403	128	531
BC	188	57	23	80	1794	312	96	408
Canada	5965	583	434	1017	62609	2527	1906	4433

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 22, 2009 to February 28, 2009 (Week 08)
	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.

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=470]

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