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2011-2012 FluWatch: February 12 to February 18, 2012 (Week 07) (PDF Version - 113 KB - 6 pages)
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Overall Influenza Summary
In week 07, six surveillance regions (within SK, ON, & NL) reported localized activity and 22 regions (within BC, AB, ON, QC, NL, PEI, & NU) reported sporadic influenza activity (see Figure 1). Nine outbreaks of influenza were reported this week: 4 in long-term care facilities (3 in ON & 1 in SK), 3 in schools (in SK) and 2 others (in ON) (Figure 3).
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 reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Figure 2. Number of influenza surveillance regions† reporting widespread or
localized influenza activity, Canada, by report week, 2011-2012 (N=56)
The proportion of positive influenza tests continued to increase and was 10.5% (378/3,470) for week 07 (Figure 4 & Figure5). Of the 378 positive influenza detections this week, 220 (58%) were positive for influenza A and 158 (42%) were positive for influenza B. To date this season, the provinces with the highest proportion of influenza B detections compared to influenza A detections include: ON, QC & the Atlantic provinces.
The proportion of influenza virus detections by type/subtype this season to date is as follows: 69.6% influenza A (60.2% - A(H3); 14.2% - A(H1N1)pdm09; 25.6% - unsubtyped) and 30.4% influenza B (Table 1).
Detailed information on age and type/subtype were received on 1,556 cases to date this season (Table 2). The proportions of cases by age group are as follows: 21.6% were < 5 years; 14.5% were between 5-19 years; 24.7% were between 20-44 years; 15.0% were between 45-64 years of age; 24.2% were ≥ 65 years; and 0.1% with age unknown.
In week 07, the proportion of tests positive for RSV declined to 16.6% (and has fluctuated between 17-19% since week 01) and remains the most prevalent among the other respiratory viruses being detected. The highest percent positives for RSV this week were reported in ON, QC and the Atlantic Region. Except for the percent positive for hMPV (6.2%) and rhinovirus (6.3%) which increased compared to the previous week, the proportion of positive tests for the other respiratory viruses declined slightly from the previous week (parainfluenza-1.6%; adenovirus-2.0%; coronavirus-6.0%) (Figure 5). For more details, see the weekly Respiratory Virus Detections in Canada report.
(February 12 to February 18, 2012)
(August 28, 2011 to February 18, 2012)
|Influenza A||B||Influenza A||B|
|A Total||A(H1)||A(H3)||Pand H1N1||A
( Un S)*
|Total||A Total||A(H1)||A(H3)||Pand H1N1||A
(Un S) *
|* Unsubtyped: The specimen was typed as influenza A, but no test for subtyping was performed. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces.
Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
(February 12 to February 18, 2012 (Week 07))
(August 28, 2011 to February 18, 2012)
|Influenza A||B||Influenza A||B|
|A Total||Pandemic H1N1||A/H3N2||A unsubtyped||Total||A Total||Pandemic H1N1||A/H3N2||A unsubtyped||Total|
|* Please note that this table reflects the number of specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. Delays in the reporting of data may cause data to change retrospectively.|
Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2011-2012
Since the start of the season, the National Microbiology Laboratory (NML) has antigenically characterized 354 influenza viruses (99 A/H3N2, 66 A/H1N1 and 189 B). All 99 A/H3N2 viruses (from BC, AB, SK, ON & QC) are antigenically related to A/Perth/16/2009. All 66 A/H1N1 viruses (from BC, AB, SK, ON & QC) are antigenically related to A/California/07/2009. Of the 189 influenza B viruses characterized, 103 (54%) (from BC, AB, SK, ON, QC, NB & NL) are antigenically related to the vaccine strain B/Brisbane/60/2008 (Victoria lineage). The remaining 86 (46%) influenza B viruses (from BC, AB, ON, QC & NB) are antigenically related to the reference virus B/Wisconsin/01/2010-like, which belongs to the Yamagata lineage. (Figure 6)
Note: The recommended components for the 2011-2012 Northern Hemisphere influenza vaccine include: A/Perth/16/2009 (H3N2), A/California/7/2009 (H1N1) and B/Brisbane/60/2008.
Since the beginning of the season, NML has tested 279 influenza viruses for resistance to oseltamivir (by phenotypic assay and/or sequencing) and 238 influenza viruses for resistance to zanamivir (by phenotypic assay) and it was found that all viruses tested were susceptible to oseltamivir and zanamivir. A total of 188 influenza A viruses (121 H3N2 and 67 H1N1) were tested for amantadine resistance; all but one influenza A(H3N2) virus tested were resistant. (Table 3)
|Virus type and subtype||Oseltamivir||Zanamivir||Amantadine|
|# tested||# resistant (%)||# tested||# resistant (%)||# tested||# resistant (%)|
|* NA - not applicable|
|A (H3N2)||94||0||79||0||121||120 (99.2%)|
|A (H1N1)||58||0||50||0||67||67 (100%)|
|B||127||0||109||0||NA *||NA *|
The national ILI consultation rate increased to 33.5 ILI consultations per 1,000 patient visits in week 07 but still remains within the expected levels for this time of year (Figure 7). The highest consultation rates this week were observed in children under 5 (64.2/1,000 visits) and in those 5 to 19 years old (47.8/1,000).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)
Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Paediatric Influenza Hospitalizations and Deaths
In week 07, 11 new laboratory-confirmed influenza-associated paediatric (16 years of age and under) hospitalizations were reported through the Immunization Monitoring Program Active (IMPACT) Four hospitalizations were due to influenza A (unsubtyped) (in BC, AB, ON & QC) and seven were due to influenza B (in BC, AB, ON & QC).
To date this season, 83 influenza-associated paediatric hospitalizations have been reported through IMPACT (from BC, AB, SK, MB, ON, QC, & NL); 47 (56.6%) were due to influenza A and 36 (43.4%) were due to influenza B. The proportion of cases by age group is as follows: 16.9% among infants <6 months of age; 18.1% among children 6-23 months of age; 36.1% were between 2-4 years; 16.9% were between 5-9 years; and 12.0% were between 10-16 years.
Note: The number of hospitalizations reported through IMPACT represents a subset of all influenza-associate paediatric hospitalizations in Canada; therefore, the number of hospitalizations included in this report may differ from those reported by other Provincial and Territorial Health Authorities.
Adult Influenza Hospitalizations and Deaths
In week 07, 22 new laboratory-confirmed influenza-associated adult hospitalizations were reported: 15 in ON, 6 in AB and 1 in NL. In addition, of the 6 hospitalizations reported in AB, 3 required admission to ICU; 2 with influenza A(H1N1)pdm09 infection and 1 with influenza A(H3N2) infection.
Note: The reason for hospitalization or cause of death does not have to be attributable to influenza in order to be reported. Influenza-associated adult hospitalizations are not reported to PHAC by the following Provinces: BC, QC, & NB. Only hospitalizations that require intensive medical care are reported by SK. ICU admissions are not reported in ON.
WHO: No new updates have been reported by the WHO since February 17, 2012.
World Health Organization influenza update
Recommended composition of influenza virus vaccines for use in the 2012-2013 northern hemisphere influenza season
The WHO recommends that the vaccines for use in the 2012-2013 influenza season (northern hemisphere winter) contain the following: an A/California/7/2009 (H1N1)pdm09-like virus; an A/Victoria/361/2011 (H3N2)-like virus; and a B/Wisconsin/1/2010-like virus.
United States: In week 6, the CDC reported that 15.5% (500/3,230) of influenza tests were positive. Since October 1, 2011, the CDC characterized 369 influenza viruses: 58 A/H1N1, 263 A/H3N2 and 48 B. Fifty-six (96.6%) of the A/H1N1 viruses were characterized as A/California/7/2009-like and 2 (3.4%) showed reduced titers with antiserum produced against A/California/7/2009. Of the 263 influenza A/H3N2 viruses that were characterized, 257 (97.7%) were A/Perth/16/2009-like and 6 (2.3%) showed reduced titers with antiserum produced against A/Perth/16/2009. Of the 48 influenza B viruses that were characterized, 22 (45.8%) were B/Brisbane/60/2008-like (B/Victoria lineage) and 26 (54.2%) belonged to the B/Yamagata lineage. The proportion of outpatient visits for ILI was 1.9%, which is below the national baseline. Widespread influenza activity was reported in 1 state (California), 12 states reported regional influenza activity, 17 states reported localized influenza activity, while the rest reported either sporadic or no activity. One influenza-associated pediatric death was reported to CDC during week 6 and was associated with influenza B virus.
Centers for Disease Control and Prevention seasonal influenza report
Europe: In week 7, influenza activity continues to increase in most of the countries in the WHO European Region. Consultation rates for ILI and acute respiratory infection (ARI) are increasing in 27 out of 42 countries; and similar to previous weeks, consultation rate were highest in young children. Approximately 46% of sentinel ILI/ARI samples tested positive for influenza of which 91% were for influenza A and 9% for influenza B. Circulation of influenza A(H3N2)virus is still prevalent, with some A(H1N1)pdm09 and influenza B detections reported. Since week 40, 218 influenza viruses have been characterized antigenically: 3 were A/California/7/2009 (H1N1)-like; 195 were A/Perth/16/2009 (H3N2)-like; 4 were B/Florida/4/2006-like (B/Yamagata/16/88 lineage), 8 were B/Bangladesh/3333/2007-like (B/Yamagata/16/88 lineage) and 8 were B/Brisbane/60/2008-like (B/Victoria/2/87 lineage).
EuroFlu weekly electronic bulletin
The WHO reported three new cases of human A/H5N1 avian influenza infection. The first case was in a 19 year-old female from Indonesia who developed symptoms on February 8, 2012, was hospitalized on February 12 and died on February 13. The other two cases were from Egypt – a 45 year-old female from Menofia governorate and a 1 year-old female from Gharbeia governorate. Both cases received oseltamivir treatment. The 45 year-old is recovering and the 1 year-old is in good medical condition.
WHO Avian influenza situation updates
FluWatch reports include data and information from the following sources: laboratory reports of positive influenza tests in Canada (National Microbiology Laboratory), sentinel physician reporting of influenza-like illness (ILI), provincial/territorial assessment of influenza activity based on various indicators, including laboratory surveillance, ILI reporting, and outbreaks, influenza-associated paediatric and adult hospitalizations, antiviral sales in Canada, and WHO and other international reports of influenza activity.
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).
Note: ILI data may be reported through sentinel physicians, emergency room visits or health line telephone calls.
* More than just sporadic as determined by the provincial/territorial epidemiologist.
† Influenza surveillance regions within the province or territory as defined by the provincial/territorial epidemiologist.
We would like to thank all the Fluwatch surveillance partners who are participating in this year's influenza surveillance program.