January 25, 20098 to January 31, 2009  (Week 04)

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Laboratory detections, ILI consultations and influenza activity levels increased from previous weeks
During week 04, influenza activity in Canada continued to increase with two regions reporting widespread influenza activity (in BC & NS) and more regions reporting localized (n=8; in BC, AB, ON & NL) and sporadic activity (n=24) (see map). The proportion of tests that were positive for influenza continued to increase (percentage positive = 9.8%; 312/3,175) (see table). Although the majority of influenza virus detections to date this season were influenza A viruses (57% or 491/1152) detections for influenza B viruses are also increasing (see graph). The ILI consultation rate increased from 17 ILI consultations per 1,000 patient visits in the previous week to 32 per 1,000 this week (see ILI graph), yet remains within the expected range. The sentinel response rate was 61%. In week 04, 18 new influenza outbreaks were reported: 1 in a LTCF (BC), 2 in hospitals (BC & NL) and 15 in schools (9 from BC & 1 in AB & 5 in NS).

Antigenic Characterization:
Since 1 September 2008, the NML has antigenically characterized 183 influenza viruses: 42 influenza A/Brisbane/59/2007(H1N1)-like (from BC, AB, SK, ON, NS & PEI), 13 influenza A/Brisbane/10/2007(H3N2)-like (from BC, AB, SK, ON & PEI), 5 influenza B/Florida/4/2006-like (from AB & ON) and 123 B/Malaysia/2506/2004-like (from AB, SK, MB, ON, QC & all 4 Atlantic provinces). 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 72 influenza A isolates (40 H1N1 and 32 H3N2) for amantadine resistance. All of the H1N1 isolates were susceptible; however all of the H3N2 isolates were resistant to amantadine (resistance = 100% or 32/32). The resistant isolates were from BC, AB, SK, ON, QC, NL & NT.

The NML has also tested 146 influenza isolates (35 A/H1N1, 13 A/H3N2 & 98 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 35/35). The resistant isolates were from BC, AB, ON, NS & PEI.

All 150 influenza isolates (39 A/H1N1, 13 A/H3N2 & 98 B) tested for zanamivir resistance to date were sensitive to zanamivir.

Oseltamivir resistance findings from Provincial laboratories:

To date this season, 67 influenza isolates in BC have been sub-typed as A/H1 and were assessed genotypically for oseltamivir resistance using an SNP assay. Sixty isolates tested positive for the H274Y mutation (resistance = 100% or 60/60), with the other 7 specimens still pending confirmatory testing.

Influenza-associated Paediatric Hospitalizations:
In week 04, 23 laboratory-confirmed influenza-associated paediatric hospitalizations were reported through the Immunization Monitoring Program Active (IMPACT) network. The cases were from BC, ON, QC & NS and 74% were due to influenza A. To date, 62 hospitalizations have been reported of which 73% (45/62) have been due to influenza A. The proportion of cases to date by age group are as follows: 19% were 0-5 month olds; 18% were 6-23 month olds; 11% were 2-4 year-olds; 16% were 5-9 year-olds; and 35% were 10-16 year-olds. The distribution of cases to date by province are as follows:10% from BC, 5% from AB, 69% from ON, 13% from QC & 3% from NS.

International:

WHO: During the weeks 3-4, the level of overall influenza activity in the world continued to intensify. Widespread influenza A activity (H1 and H3) was reported in Japan. In North America and Hong Kong Special Administrative Region of China influenza activity increased but remained relatively low.

• WHO

CDC: During week 04, influenza activity continued to slowly increase in the United States. Of the 3,711 specimens tested this week for influenza viruses, 588 (15.8%) were positive. Since 1 October 2008, the CDC has antigenically characterized 229 influenza viruses: 142 influenza A(H1) (all A/Brisbane/59/2007-like), 35 A(H3) (all A/Brisbane/10/2007-like) and 52 influenza B (17 were B/Florida/04/2006-like belonging to the B/Yamagata lineage and the other 35 belonged to the B/Victoria lineage). Since 1 October, 2008, 269 influenza viruses (165 A(H1N1), 37 A (H3N2), and 67 B) have been tested for resistance to neuraminidase inhibitors. Of the A(H1N1) viruses tested, 98.2% (162/165) 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 202 influenza A viruses (165 H1, 37 H3) for amantadine resistance: 2 of the H1N1 viruses was resistant to amantadine (1.2%, 2/165) however all the H3N2 viruses (100%) were resistant. One case of human infection with a swine influenza A (H1N1) virus was reported by the South Dakota Department of Health during week 03 and an investigation is currently underway to determine the source of illness.

• CDC

EISS: Influenza activity continues to increase in eastern Europe, however it is starting to decrease in the west. Although influenza A(H3N2) continues to be the dominant influenza virus circulating in Europe, the number of influenza B viruses continues to show a rising trend. With the exception of the few B/Victoria lineage viruses, the viruses circulating in Europe are similar to the strains included in the current influenza vaccine. Of the 115 A(H3N2) isolates that were tested for adamantanes susceptibility, 115 (100%) were resistant. Of the 75 A(H1N1) virus isolates tested for resistance against neuraminidase inhibitors, 73 (97%) were resistant to oseltamivir, but all were sensitive to zanamivir.

• EISS

Human Avian Influenza: Since 31 January 2009, the WHO has reported 2 new cases of human H5N1 avian influenza infection from China and Egypt. Both cases were hospitalized and remain in stable condition.

• 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: January 25, 2009 to January 31, 2009				Season to Date: August 24, 2008 to January 31, 2009
	Total # Influenza Tests	# of Positive Tests			Total # Influenza Tests	# of Positive Tests
		Influenza A	Influenza B	Total		Influenza A	Influenza B	Total
NL	25	3	2	5	274	4	2	6
PE	17	4	2	6	93	5	4	9
NS	40	3	5	8	391	5	5	10
NB	50	1	7	8	383	7	15	22
QC	1268	82	17	99	11269	233	30	263
ON	1303	42	91	133	13739	146	331	477
MB	71	0	0	0	1117	0	2	2
SK	248	7	5	12	2226	17	5	22
AB	NA	NA	NA	0	10168	114	77	191
BC	153	31	10	41	1124	130	20	150
Canada	3175	173	139	312	40784	661	491	1152

 

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, January 25, 2009 to January 31, 2009 (Week 04)
	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=183]

{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.

Single Maps | Dual Maps | Animated Maps | FluWatch Reports

Definitions for the 2008-2009 season