Re: Canada FluWatch Weekly Reports 2011-2012 Season Week 1
January 1 to January 7 2012 (Week 01)
Posted 2012-01-13
For readers interested in the <ABBR title="Portable Document Format">PDF</ABBR> version, the document is available for downloading or viewing:
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Overall Influenza Summary
In week 01, three surveillance regions (within BC & QC) reported localized activity and 18 regions (within BC, AB, SK, ON & QC) reported sporadic influenza activity (see Figure 1). Three outbreaks of influenza were reported this week, 1 in a long-term care facility (in QC) and 2 in hospitals (in BC) (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 1
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.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions<SUP title="sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in">?</SUP> reporting widespread or
localized influenza activity, Canada, by report week, 2011-2012 (N=56)
? sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
Text equivalent for figure 2Number of influenza surveillance regions? reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012
Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012
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Influenza and Other Respiratory Virus Detections
In week 01, the proportion of positive influenza tests increased slightly to 2.9% (109/3,697) (Figure 4 & 5). Of the provinces reporting positive influenza detections, the proportion of tests positive ranged from a high of 16.5% in QC to a low of 0.7% in <ABBR title=Manitoba>MB</ABBR>.
The proportion of influenza virus detections by type/subtype this season to date is as follows: 82.3% influenza A (74% - A(H3); 7% - A(H1N1)pdm09; 19% - unsubtyped) and 17.7% influenza B (Table 1).
Detailed information on age and type/subtype were received on 332 cases this season to date (Table 2). ). The proportions of cases by age group are as follows: 20.5% were < 5 years; 11.8% were between 5-19 years; 27.1% were between 20-44 years; 14.8% were between 45-64 years of age; and 26% were ≥ 65 years.
In week 01, the proportion of tests positive for <ABBR title="Respiratory syncytial virus">RSV</ABBR> decreased slightly (16.6%); but it remains the most prevalent among the other respiratory viruses being detected. The highest percent positives for RSV were reported in <ABBR title="Prince Edward Island ">PEI</ABBR>, <ABBR title="New Brunswick ">NB</ABBR>, QC and ON. The proportion of positive tests for the other respiratory viruses remained similar to previous weeks (rhinovirus-6.2%; parainfluenza-3.5%; adenovirus-3.7%; <ABBR title="Human metapneumovirus">hMPV</ABBR>-9.0%; coronavirus-4.3%) (Figure 5). For more details, see the weekly Respiratory Virus Detections in Canada report.
<TABLE class=widthFull border=1 cellSpacing=0 cellPadding=2><CAPTION class=alignCenter>Table 1: Weekly & Cumulative numbers of positive influenza specimens
by Provincial Laboratories, Canada, 2011-2012
</CAPTION><THEAD><TR class=bg-colour-blue><TH rowSpan=3 scope=col>Reporting provinces</TH><TH colSpan=6 scope=colgroup>Weekly
(January 1 to January 7 2012 (Week 01))
</TH><TH colSpan=6 scope=colgroup>Cumulative
(August 29, 2010 to January 7, 2012)
</TH></TR><TR class=bg-colour-blue><TH colSpan=5 scope=colgroup>Influenza A</TH><TH scope=col>B</TH><TH colSpan=5 scope=colgroup>Influenza A</TH><TH scope=col>B</TH></TR><TR class=bg-colour-blue><TH scope=col>A Total</TH><TH scope=col>A(H1)</TH><TH scope=col>A(H3)</TH><TH scope=col>Pand H1N1</TH><TH class=noWrap scope=col>A
(<ABBR title=unsubtyped>Un S</ABBR>)*
</TH><TH scope=col>Total</TH><TH scope=col>A Total</TH><TH scope=col>A(H1)</TH><TH scope=col>A(H3)</TH><TH scope=col>Pand H1N1</TH><TH class=noWrap scope=col>A
(Un S)*
</TH><TH scope=col>Total</TH></TR></THEAD><TFOOT><TR><TD class=fontSize85 colSpan=13>* 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.
</TD></TR></TFOOT><TBODY><TR><TH class=bg-colour-blue scope=row><ABBR title="British Columbia ">BC</ABBR></TH><TD class=alignRight>33</TD><TD class=alignRight>0</TD><TD class=alignRight>33</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>1</TD><TD class=alignRight>140</TD><TD class=alignRight>0</TD><TD class=alignRight>140</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>7</TD></TR><TR><TH class=bg-colour-blue scope=row><ABBR title=Alberta>AB</ABBR></TH><TD class=alignRight>12</TD><TD class=alignRight>0</TD><TD class=alignRight>12</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>5</TD><TD class=alignRight>71</TD><TD class=alignRight>0</TD><TD class=alignRight>67</TD><TD class=alignRight>1</TD><TD class=alignRight>3</TD><TD class=alignRight>12</TD></TR><TR><TH class=bg-colour-blue scope=row><ABBR title=Saskatchewan>SK</ABBR></TH><TD class=alignRight>7</TD><TD class=alignRight>0</TD><TD class=alignRight>6</TD><TD class=alignRight>0</TD><TD class=alignRight>1</TD><TD class=alignRight>0</TD><TD class=alignRight>42</TD><TD class=alignRight>0</TD><TD class=alignRight>37</TD><TD class=alignRight>0</TD><TD class=alignRight>5</TD><TD class=alignRight>0</TD></TR><TR><TH class=bg-colour-blue scope=row><ABBR title=Manitoba>MB</ABBR></TH><TD class=alignRight>1</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>1</TD><TD class=alignRight>0</TD><TD class=alignRight>1</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>1</TD><TD class=alignRight>0</TD></TR><TR><TH class=bg-colour-blue scope=row><ABBR title=Ontario>ON</ABBR></TH><TD class=alignRight>17</TD><TD class=alignRight>0</TD><TD class=alignRight>5</TD><TD class=alignRight>8</TD><TD class=alignRight>4</TD><TD class=alignRight>10</TD><TD class=alignRight>52</TD><TD class=alignRight>0</TD><TD class=alignRight>21</TD><TD class=alignRight>23</TD><TD class=alignRight>8</TD><TD class=alignRight>28</TD></TR><TR><TH class=bg-colour-blue scope=row><ABBR title=Quebec>QC</ABBR></TH><TD class=alignRight>14</TD><TD class=alignRight>0</TD><TD class=alignRight>3</TD><TD class=alignRight>0</TD><TD class=alignRight>11</TD><TD class=alignRight>9</TD><TD class=alignRight>56</TD><TD class=alignRight>0</TD><TD class=alignRight>3</TD><TD class=alignRight>2</TD><TD class=alignRight>51</TD><TD class=alignRight>30</TD></TR><TR><TH class=bg-colour-blue scope=row><ABBR title="New Brunswick">NB</ABBR></TH><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>1</TD></TR><TR><TH class=bg-colour-blue scope=row><ABBR title="Nova Scotia ">NS</ABBR></TH><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD></TR><TR><TH class=bg-colour-blue scope=row><ABBR title="Prince Edward Island ">PE</ABBR></TH><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD></TR><TR><TH class=bg-colour-blue scope=row><ABBR title="Newfoundland/Labrador ">NL</ABBR></TH><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD></TR><TR><TH class=bg-colour-blue scope=row>Canada</TH><TD class=alignRight>84</TD><TD class=alignRight>0</TD><TD class=alignRight>59</TD><TD class=alignRight>8</TD><TD class=alignRight>17</TD><TD class=alignRight>25</TD><TD class=alignRight>362</TD><TD class=alignRight>0</TD><TD class=alignRight>268</TD><TD class=alignRight>26</TD><TD class=alignRight>68</TD><TD class=alignRight>78</TD></TR></TBODY></TABLE>
<TABLE class=widthFull border=1 cellSpacing=0 cellPadding=2><CAPTION>Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups
reported through case-based laboratory reporting, Canada, 2011-2012*
</CAPTION><THEAD><TR class=bg-colour-yellow><TH rowSpan=3 scope=col>Age groups</TH><TH colSpan=5 scope=colgroup>Weekly
(January 1 to January 7 2012 (Week 01))
</TH><TH colSpan=5 scope=colgroup>Cumulative
(Aug. 29, 2010 to January 7, 2012)
</TH></TR><TR class=bg-colour-yellow><TH colSpan=4 scope=colgroup>Influenza A</TH><TH scope=col>B</TH><TH colSpan=4 scope=colgroup>Influenza A</TH><TH scope=col>B</TH></TR><TR class=bg-colour-yellow><TH scope=col>A Total</TH><TH scope=col>Pandemic H1N1</TH><TH scope=col>A/H3N2</TH><TH scope=col>A unsubtyped</TH><TH scope=col>Total</TH><TH scope=col>A Total</TH><TH scope=col>Pandemic H1N1</TH><TH scope=col>A/H3N2</TH><TH scope=col>A unsubtyped</TH><TH scope=col>Total</TH></TR></THEAD><TFOOT><TR><TD class=fontSize85 colSpan=11>* 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.
</TD></TR></TFOOT><TBODY><TR><TH scope=row>< 5</TH><TD class=alignRight>5</TD><TD class=alignRight>1</TD><TD class=alignRight>4</TD><TD class=alignRight>0</TD><TD class=alignRight>3</TD><TD class=alignRight>55</TD><TD class=alignRight>10</TD><TD class=alignRight>43</TD><TD class=alignRight>2</TD><TD class=alignRight>13</TD></TR><TR><TH scope=row>5-19</TH><TD class=alignRight>3</TD><TD class=alignRight>0</TD><TD class=alignRight>3</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>34</TD><TD class=alignRight>2</TD><TD class=alignRight>31</TD><TD class=alignRight>1</TD><TD class=alignRight>5</TD></TR><TR><TH scope=row>20-44</TH><TD class=alignRight>12</TD><TD class=alignRight>0</TD><TD class=alignRight>12</TD><TD class=alignRight>0</TD><TD class=alignRight>1</TD><TD class=alignRight>82</TD><TD class=alignRight>4</TD><TD class=alignRight>75</TD><TD class=alignRight>3</TD><TD class=alignRight>8</TD></TR><TR><TH scope=row>45-64</TH><TD class=alignRight>5</TD><TD class=alignRight>1</TD><TD class=alignRight>4</TD><TD class=alignRight>0</TD><TD class=alignRight>1</TD><TD class=alignRight>43</TD><TD class=alignRight>1</TD><TD class=alignRight>41</TD><TD class=alignRight>1</TD><TD class=alignRight>6</TD></TR><TR><TH scope=row>65+</TH><TD class=alignRight>4</TD><TD class=alignRight>2</TD><TD class=alignRight>2</TD><TD class=alignRight>0</TD><TD class=alignRight>2</TD><TD class=alignRight>81</TD><TD class=alignRight>3</TD><TD class=alignRight>78</TD><TD class=alignRight>0</TD><TD class=alignRight>5</TD></TR><TR><TH scope=row>Unknown</TH><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD></TR><TR><TH scope=row>Total</TH><TD class=alignRight>29</TD><TD class=alignRight>4</TD><TD class=alignRight>25</TD><TD class=alignRight>0</TD><TD class=alignRight>7</TD><TD class=alignRight>295</TD><TD class=alignRight>20</TD><TD class=alignRight>268</TD><TD class=alignRight>7</TD><TD class=alignRight>37</TD></TR></TBODY></TABLE>
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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2011-2012
Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2011-2012
Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012
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Influenza strain characterizations
Since the start of the season, the National Microbiology Laboratory (NML) has antigenically characterized 61 influenza viruses (27 A/H3N2, 8 A/H1N1 and 26 B). All 27 A/H3N2 viruses (from BC, AB, SK & ON) are antigenically related to A/Perth/16/2009. All 8 A/H1N1 viruses (from QC & ON) are antigenically related to A/California/07/2009. Fourteen of the influenza B viruses characterized (from BC, AB, ON & QC) are antigenically related to the vaccine strain B/Brisbane/60/2008 (Victoria lineage). The other 12 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)
Figure 6. Influenza strain characterizations, Canada, 2011-2012, N = 61
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.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012
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Antiviral resistance
Since the beginning of the season, NML has tested 61 influenza viruses (27 A/H3N2, 9 A/H1N1 and 25 B) for resistance to oseltamivir (by phenotypic assay and/or sequencing) and for resistance to zanamivir (by phenotypic assay) and it was found that all 61 viruses were susceptible to oseltamivir and zanamivir. A total of 42 influenza A viruses (36 H3N2 and 6 H1N1) were tested for amantadine resistance and all 42 were found to be resistant. (Table 3)
<TABLE class=widthFull border=1 cellSpacing=0 cellPadding=2><CAPTION>Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2011-2012 </CAPTION><THEAD><TR class=bg-colour-yellow><TH rowSpan=2 scope=col>Virus type and subtype</TH><TH colSpan=2 scope=colgroup>Oseltamivir</TH><TH colSpan=2 scope=colgroup>Zanamivir</TH><TH colSpan=2 scope=colgroup>Amantadine</TH></TR><TR class=bg-colour-yellow><TH scope=col># tested</TH><TH scope=col># resistant (%)</TH><TH scope=col># tested</TH><TH scope=col># resistant (%)</TH><TH scope=col># tested</TH><TH scope=col># resistant (%)</TH></TR></THEAD><TFOOT><TR><TD class=fontSize85 colSpan=7 scope=row><SUP>*</SUP> NA ? not applicable</TD></TR></TFOOT><TBODY><TR><TH class="alignLeft bg-colour-blue" scope=row>A (H3N2)</TH><TD class=alignRight>27</TD><TD class=alignRight>0</TD><TD class=alignRight>27</TD><TD class=alignRight>0</TD><TD class=alignRight>36</TD><TD class=alignRight>36 (100%)</TD></TR><TR><TH class="alignLeft bg-colour-blue" scope=row>A (H1N1)</TH><TD class=alignRight>9</TD><TD class=alignRight>0</TD><TD class=alignRight>9</TD><TD class=alignRight>0</TD><TD class=alignRight>6</TD><TD class=alignRight>6 (100%)</TD></TR><TR><TH class="alignLeft bg-colour-blue" scope=row>B</TH><TD class=alignRight>25</TD><TD class=alignRight>0</TD><TD class=alignRight>25</TD><TD class=alignRight>0</TD><TD class=alignRight>NA<SUP>* </SUP></TD><TD class=alignRight>NA<SUP>* </SUP></TD></TR><TR><TH class="alignLeft bg-colour-blue" scope=row>TOTAL</TH><TD class=alignRight>61</TD><TD class=alignRight>0</TD><TD class=alignRight>61</TD><TD class=alignRight>0</TD><TD class=alignRight>42</TD><TD class=alignRight>42 (100%)</TD></TR></TBODY></TABLE>
Influenza-like Illness (ILI) Consultation Rate
The national ILI consultation rate increased from previous weeks to 35.0 ILI consultations per 1,000 patient visits in week 01 and is within the expected levels for this time of year (Figure 7). The highest consultation rates this week were observed in children under 5 (120.8/1,000 visits) and those 5 to 19 years old (50.1/1,000).
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.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)
Severe Illness Surveillance
Paediatric Influenza Hospitalizations and Deaths
In week 01, six new laboratory-confirmed influenza-associated paediatric (16 years of age and under) hospitalizations were reported through the Immunization Monitoring Program Active (<ABBR title="Immunization Monitoring Program Active">IMPACT</ABBR>)network. Two hospitalizations were due to influenza A (in BC & AB) and 4 were due to influenza B (1 in AB, 1 in ON & 2 in QC).
To date this season, 30 cases have been reported (from BC, AB, SK, ON & QC); 20 (66.7%) were due to influenza A and 10 (33.3%) were due to influenza B. The proportion of cases by age group is as follows: 16.7% among infants <6 months of age; 13.3% among children 6-24 months of age; 46.7% were between 2-4 years; 10% were between 5-9 years; and 13.3% were between 10-16 years.
Adult Influenza Hospitalizations and Deaths
In week 01, 8 new laboratory-confirmed influenza-associated adult hospitalizations were reported: 1 in AB & 7 in ON.
To date this season, 23 influenza-associated adult hospitalizations have been reported from two provinces (AB & ON). The proportion of cases by age group is as follows: 30% were in those 20-44 years of age; 13% were in those 45-64 years of age and 57% were in those ≥ 65 years.
Note: 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.
.../
January 1 to January 7 2012 (Week 01)
Posted 2012-01-13
For readers interested in the <ABBR title="Portable Document Format">PDF</ABBR> version, the document is available for downloading or viewing:
<A title="Flu Watch (Version PDF, 113 KB - 6 pages)" href="http://www.phac-aspc.gc.ca/fluwatch/11-12/w01_12/pdf/fw2012-01-eng.pdf" jQuery1326506674545="2">2011-2012 FluWatch: January 1 to January 7 2012 (Week 01) (<ABBR title="Portable Document Format">PDF</ABBR> Version - 113 <ABBR title=Kilobytes>KB</ABBR> - 6 pages)
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Overall Influenza Summary
- Influenza activity in Canada is similar to previous weeks with only certain regions reporting increased activity (i.e. western provinces, <ABBR title=Ontario>ON</ABBR> and <ABBR title=Quebec>QC</ABBR>) while activity remains low in the rest (i.e. Atlantic region, MB and the Territories)
- Three regions (within BC & QC) reported localized influenza activity and 18 regions (within <ABBR title="British Columbia ">BC</ABBR>, <ABBR title="Alberta ">AB</ABBR>, <ABBR title=Saskatchewan>SK</ABBR>, ON & QC) reported sporadic influenza activity
- Three outbreaks of influenza were reported this week (2 in hospitals and 1 in a <ABBR title="long-term care facilities">LTCF</ABBR>)
- In week 01, 109 laboratory detections of influenza were reported (59 A/H3, 8 A(H1N1)pdm09, 17 A unsubtyped and 25 B)
- Fourteen influenza-associated hospitalizations were reported this week (6 paediatric and 8 adult)
- The national <ABBR title="Influenza-like illness">ILI</ABBR> consultation rate increased this week compared to previous weeks but remains within expected levels for this time of year.
In week 01, three surveillance regions (within BC & QC) reported localized activity and 18 regions (within BC, AB, SK, ON & QC) reported sporadic influenza activity (see Figure 1). Three outbreaks of influenza were reported this week, 1 in a long-term care facility (in QC) and 2 in hospitals (in BC) (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 1
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.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions<SUP title="sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in">?</SUP> reporting widespread or
localized influenza activity, Canada, by report week, 2011-2012 (N=56)
? sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
Text equivalent for figure 2Number of influenza surveillance regions? reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012
Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012
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Influenza and Other Respiratory Virus Detections
In week 01, the proportion of positive influenza tests increased slightly to 2.9% (109/3,697) (Figure 4 & 5). Of the provinces reporting positive influenza detections, the proportion of tests positive ranged from a high of 16.5% in QC to a low of 0.7% in <ABBR title=Manitoba>MB</ABBR>.
The proportion of influenza virus detections by type/subtype this season to date is as follows: 82.3% influenza A (74% - A(H3); 7% - A(H1N1)pdm09; 19% - unsubtyped) and 17.7% influenza B (Table 1).
Detailed information on age and type/subtype were received on 332 cases this season to date (Table 2). ). The proportions of cases by age group are as follows: 20.5% were < 5 years; 11.8% were between 5-19 years; 27.1% were between 20-44 years; 14.8% were between 45-64 years of age; and 26% were ≥ 65 years.
In week 01, the proportion of tests positive for <ABBR title="Respiratory syncytial virus">RSV</ABBR> decreased slightly (16.6%); but it remains the most prevalent among the other respiratory viruses being detected. The highest percent positives for RSV were reported in <ABBR title="Prince Edward Island ">PEI</ABBR>, <ABBR title="New Brunswick ">NB</ABBR>, QC and ON. The proportion of positive tests for the other respiratory viruses remained similar to previous weeks (rhinovirus-6.2%; parainfluenza-3.5%; adenovirus-3.7%; <ABBR title="Human metapneumovirus">hMPV</ABBR>-9.0%; coronavirus-4.3%) (Figure 5). For more details, see the weekly Respiratory Virus Detections in Canada report.
<TABLE class=widthFull border=1 cellSpacing=0 cellPadding=2><CAPTION class=alignCenter>Table 1: Weekly & Cumulative numbers of positive influenza specimens
by Provincial Laboratories, Canada, 2011-2012
</CAPTION><THEAD><TR class=bg-colour-blue><TH rowSpan=3 scope=col>Reporting provinces</TH><TH colSpan=6 scope=colgroup>Weekly
(January 1 to January 7 2012 (Week 01))
</TH><TH colSpan=6 scope=colgroup>Cumulative
(August 29, 2010 to January 7, 2012)
</TH></TR><TR class=bg-colour-blue><TH colSpan=5 scope=colgroup>Influenza A</TH><TH scope=col>B</TH><TH colSpan=5 scope=colgroup>Influenza A</TH><TH scope=col>B</TH></TR><TR class=bg-colour-blue><TH scope=col>A Total</TH><TH scope=col>A(H1)</TH><TH scope=col>A(H3)</TH><TH scope=col>Pand H1N1</TH><TH class=noWrap scope=col>A
(<ABBR title=unsubtyped>Un S</ABBR>)*
</TH><TH scope=col>Total</TH><TH scope=col>A Total</TH><TH scope=col>A(H1)</TH><TH scope=col>A(H3)</TH><TH scope=col>Pand H1N1</TH><TH class=noWrap scope=col>A
(Un S)*
</TH><TH scope=col>Total</TH></TR></THEAD><TFOOT><TR><TD class=fontSize85 colSpan=13>* 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.
</TD></TR></TFOOT><TBODY><TR><TH class=bg-colour-blue scope=row><ABBR title="British Columbia ">BC</ABBR></TH><TD class=alignRight>33</TD><TD class=alignRight>0</TD><TD class=alignRight>33</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>1</TD><TD class=alignRight>140</TD><TD class=alignRight>0</TD><TD class=alignRight>140</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>7</TD></TR><TR><TH class=bg-colour-blue scope=row><ABBR title=Alberta>AB</ABBR></TH><TD class=alignRight>12</TD><TD class=alignRight>0</TD><TD class=alignRight>12</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>5</TD><TD class=alignRight>71</TD><TD class=alignRight>0</TD><TD class=alignRight>67</TD><TD class=alignRight>1</TD><TD class=alignRight>3</TD><TD class=alignRight>12</TD></TR><TR><TH class=bg-colour-blue scope=row><ABBR title=Saskatchewan>SK</ABBR></TH><TD class=alignRight>7</TD><TD class=alignRight>0</TD><TD class=alignRight>6</TD><TD class=alignRight>0</TD><TD class=alignRight>1</TD><TD class=alignRight>0</TD><TD class=alignRight>42</TD><TD class=alignRight>0</TD><TD class=alignRight>37</TD><TD class=alignRight>0</TD><TD class=alignRight>5</TD><TD class=alignRight>0</TD></TR><TR><TH class=bg-colour-blue scope=row><ABBR title=Manitoba>MB</ABBR></TH><TD class=alignRight>1</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>1</TD><TD class=alignRight>0</TD><TD class=alignRight>1</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>1</TD><TD class=alignRight>0</TD></TR><TR><TH class=bg-colour-blue scope=row><ABBR title=Ontario>ON</ABBR></TH><TD class=alignRight>17</TD><TD class=alignRight>0</TD><TD class=alignRight>5</TD><TD class=alignRight>8</TD><TD class=alignRight>4</TD><TD class=alignRight>10</TD><TD class=alignRight>52</TD><TD class=alignRight>0</TD><TD class=alignRight>21</TD><TD class=alignRight>23</TD><TD class=alignRight>8</TD><TD class=alignRight>28</TD></TR><TR><TH class=bg-colour-blue scope=row><ABBR title=Quebec>QC</ABBR></TH><TD class=alignRight>14</TD><TD class=alignRight>0</TD><TD class=alignRight>3</TD><TD class=alignRight>0</TD><TD class=alignRight>11</TD><TD class=alignRight>9</TD><TD class=alignRight>56</TD><TD class=alignRight>0</TD><TD class=alignRight>3</TD><TD class=alignRight>2</TD><TD class=alignRight>51</TD><TD class=alignRight>30</TD></TR><TR><TH class=bg-colour-blue scope=row><ABBR title="New Brunswick">NB</ABBR></TH><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>1</TD></TR><TR><TH class=bg-colour-blue scope=row><ABBR title="Nova Scotia ">NS</ABBR></TH><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD></TR><TR><TH class=bg-colour-blue scope=row><ABBR title="Prince Edward Island ">PE</ABBR></TH><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD></TR><TR><TH class=bg-colour-blue scope=row><ABBR title="Newfoundland/Labrador ">NL</ABBR></TH><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD></TR><TR><TH class=bg-colour-blue scope=row>Canada</TH><TD class=alignRight>84</TD><TD class=alignRight>0</TD><TD class=alignRight>59</TD><TD class=alignRight>8</TD><TD class=alignRight>17</TD><TD class=alignRight>25</TD><TD class=alignRight>362</TD><TD class=alignRight>0</TD><TD class=alignRight>268</TD><TD class=alignRight>26</TD><TD class=alignRight>68</TD><TD class=alignRight>78</TD></TR></TBODY></TABLE>
<TABLE class=widthFull border=1 cellSpacing=0 cellPadding=2><CAPTION>Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups
reported through case-based laboratory reporting, Canada, 2011-2012*
</CAPTION><THEAD><TR class=bg-colour-yellow><TH rowSpan=3 scope=col>Age groups</TH><TH colSpan=5 scope=colgroup>Weekly
(January 1 to January 7 2012 (Week 01))
</TH><TH colSpan=5 scope=colgroup>Cumulative
(Aug. 29, 2010 to January 7, 2012)
</TH></TR><TR class=bg-colour-yellow><TH colSpan=4 scope=colgroup>Influenza A</TH><TH scope=col>B</TH><TH colSpan=4 scope=colgroup>Influenza A</TH><TH scope=col>B</TH></TR><TR class=bg-colour-yellow><TH scope=col>A Total</TH><TH scope=col>Pandemic H1N1</TH><TH scope=col>A/H3N2</TH><TH scope=col>A unsubtyped</TH><TH scope=col>Total</TH><TH scope=col>A Total</TH><TH scope=col>Pandemic H1N1</TH><TH scope=col>A/H3N2</TH><TH scope=col>A unsubtyped</TH><TH scope=col>Total</TH></TR></THEAD><TFOOT><TR><TD class=fontSize85 colSpan=11>* 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.
</TD></TR></TFOOT><TBODY><TR><TH scope=row>< 5</TH><TD class=alignRight>5</TD><TD class=alignRight>1</TD><TD class=alignRight>4</TD><TD class=alignRight>0</TD><TD class=alignRight>3</TD><TD class=alignRight>55</TD><TD class=alignRight>10</TD><TD class=alignRight>43</TD><TD class=alignRight>2</TD><TD class=alignRight>13</TD></TR><TR><TH scope=row>5-19</TH><TD class=alignRight>3</TD><TD class=alignRight>0</TD><TD class=alignRight>3</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>34</TD><TD class=alignRight>2</TD><TD class=alignRight>31</TD><TD class=alignRight>1</TD><TD class=alignRight>5</TD></TR><TR><TH scope=row>20-44</TH><TD class=alignRight>12</TD><TD class=alignRight>0</TD><TD class=alignRight>12</TD><TD class=alignRight>0</TD><TD class=alignRight>1</TD><TD class=alignRight>82</TD><TD class=alignRight>4</TD><TD class=alignRight>75</TD><TD class=alignRight>3</TD><TD class=alignRight>8</TD></TR><TR><TH scope=row>45-64</TH><TD class=alignRight>5</TD><TD class=alignRight>1</TD><TD class=alignRight>4</TD><TD class=alignRight>0</TD><TD class=alignRight>1</TD><TD class=alignRight>43</TD><TD class=alignRight>1</TD><TD class=alignRight>41</TD><TD class=alignRight>1</TD><TD class=alignRight>6</TD></TR><TR><TH scope=row>65+</TH><TD class=alignRight>4</TD><TD class=alignRight>2</TD><TD class=alignRight>2</TD><TD class=alignRight>0</TD><TD class=alignRight>2</TD><TD class=alignRight>81</TD><TD class=alignRight>3</TD><TD class=alignRight>78</TD><TD class=alignRight>0</TD><TD class=alignRight>5</TD></TR><TR><TH scope=row>Unknown</TH><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD></TR><TR><TH scope=row>Total</TH><TD class=alignRight>29</TD><TD class=alignRight>4</TD><TD class=alignRight>25</TD><TD class=alignRight>0</TD><TD class=alignRight>7</TD><TD class=alignRight>295</TD><TD class=alignRight>20</TD><TD class=alignRight>268</TD><TD class=alignRight>7</TD><TD class=alignRight>37</TD></TR></TBODY></TABLE>
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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2011-2012
Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2011-2012
Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012
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Influenza strain characterizations
Since the start of the season, the National Microbiology Laboratory (NML) has antigenically characterized 61 influenza viruses (27 A/H3N2, 8 A/H1N1 and 26 B). All 27 A/H3N2 viruses (from BC, AB, SK & ON) are antigenically related to A/Perth/16/2009. All 8 A/H1N1 viruses (from QC & ON) are antigenically related to A/California/07/2009. Fourteen of the influenza B viruses characterized (from BC, AB, ON & QC) are antigenically related to the vaccine strain B/Brisbane/60/2008 (Victoria lineage). The other 12 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)
Figure 6. Influenza strain characterizations, Canada, 2011-2012, N = 61
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.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012
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Antiviral resistance
Since the beginning of the season, NML has tested 61 influenza viruses (27 A/H3N2, 9 A/H1N1 and 25 B) for resistance to oseltamivir (by phenotypic assay and/or sequencing) and for resistance to zanamivir (by phenotypic assay) and it was found that all 61 viruses were susceptible to oseltamivir and zanamivir. A total of 42 influenza A viruses (36 H3N2 and 6 H1N1) were tested for amantadine resistance and all 42 were found to be resistant. (Table 3)
<TABLE class=widthFull border=1 cellSpacing=0 cellPadding=2><CAPTION>Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2011-2012 </CAPTION><THEAD><TR class=bg-colour-yellow><TH rowSpan=2 scope=col>Virus type and subtype</TH><TH colSpan=2 scope=colgroup>Oseltamivir</TH><TH colSpan=2 scope=colgroup>Zanamivir</TH><TH colSpan=2 scope=colgroup>Amantadine</TH></TR><TR class=bg-colour-yellow><TH scope=col># tested</TH><TH scope=col># resistant (%)</TH><TH scope=col># tested</TH><TH scope=col># resistant (%)</TH><TH scope=col># tested</TH><TH scope=col># resistant (%)</TH></TR></THEAD><TFOOT><TR><TD class=fontSize85 colSpan=7 scope=row><SUP>*</SUP> NA ? not applicable</TD></TR></TFOOT><TBODY><TR><TH class="alignLeft bg-colour-blue" scope=row>A (H3N2)</TH><TD class=alignRight>27</TD><TD class=alignRight>0</TD><TD class=alignRight>27</TD><TD class=alignRight>0</TD><TD class=alignRight>36</TD><TD class=alignRight>36 (100%)</TD></TR><TR><TH class="alignLeft bg-colour-blue" scope=row>A (H1N1)</TH><TD class=alignRight>9</TD><TD class=alignRight>0</TD><TD class=alignRight>9</TD><TD class=alignRight>0</TD><TD class=alignRight>6</TD><TD class=alignRight>6 (100%)</TD></TR><TR><TH class="alignLeft bg-colour-blue" scope=row>B</TH><TD class=alignRight>25</TD><TD class=alignRight>0</TD><TD class=alignRight>25</TD><TD class=alignRight>0</TD><TD class=alignRight>NA<SUP>* </SUP></TD><TD class=alignRight>NA<SUP>* </SUP></TD></TR><TR><TH class="alignLeft bg-colour-blue" scope=row>TOTAL</TH><TD class=alignRight>61</TD><TD class=alignRight>0</TD><TD class=alignRight>61</TD><TD class=alignRight>0</TD><TD class=alignRight>42</TD><TD class=alignRight>42 (100%)</TD></TR></TBODY></TABLE>
Influenza-like Illness (ILI) Consultation Rate
The national ILI consultation rate increased from previous weeks to 35.0 ILI consultations per 1,000 patient visits in week 01 and is within the expected levels for this time of year (Figure 7). The highest consultation rates this week were observed in children under 5 (120.8/1,000 visits) and those 5 to 19 years old (50.1/1,000).
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.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)
Severe Illness Surveillance
Paediatric Influenza Hospitalizations and Deaths
In week 01, six new laboratory-confirmed influenza-associated paediatric (16 years of age and under) hospitalizations were reported through the Immunization Monitoring Program Active (<ABBR title="Immunization Monitoring Program Active">IMPACT</ABBR>)network. Two hospitalizations were due to influenza A (in BC & AB) and 4 were due to influenza B (1 in AB, 1 in ON & 2 in QC).
To date this season, 30 cases have been reported (from BC, AB, SK, ON & QC); 20 (66.7%) were due to influenza A and 10 (33.3%) were due to influenza B. The proportion of cases by age group is as follows: 16.7% among infants <6 months of age; 13.3% among children 6-24 months of age; 46.7% were between 2-4 years; 10% were between 5-9 years; and 13.3% were between 10-16 years.
Adult Influenza Hospitalizations and Deaths
In week 01, 8 new laboratory-confirmed influenza-associated adult hospitalizations were reported: 1 in AB & 7 in ON.
To date this season, 23 influenza-associated adult hospitalizations have been reported from two provinces (AB & ON). The proportion of cases by age group is as follows: 30% were in those 20-44 years of age; 13% were in those 45-64 years of age and 57% were in those ≥ 65 years.
Note: 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.
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