Communicable Disease Surveillance Unit Weekly Influenza Bulletin by dfsdf224s

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									Communicable Disease                                                                                      Weekly Influenza Bulletin
Surveillance Unit                                                                                                  2010/11 Season

             Weekly Influenza Bulletin – Week 52 (December 26, 2010 to January 1, 2011)

Recent Influenza Activity:
Overall, the influenza activity in Toronto in week 52 was similar to the activity in week
51. One hundred and thirty-eight new lab-confirmed cases of influenza A were reported
in week 52 (Table 1). Of these, two cases were influenza subtype B.

Among the 515 lab-confirmed influenza cases reported to date in the 2010/2011
influenza season, 51% (n=264) were older than 65 years of age (Figure 2). The median
age was 66 years with a range of less than 1 year to 100 years of age.

In week 52, nine new influenza outbreaks were reported in Toronto institutions (Table
1).

The current WHO phase of pandemic alert for avian influenza H5N1 is 3.

 Table 1. Sum mary of new and cumulative influenza cases and institutional
 outbreaks by virus type. R eported week 52* (December 26, 2010 to January 01,
 2011) and season to date (September 01, 2010 to January 01, 2011).

                                                                                 Week 52                     Season to date
                        †
 Lab-confirmed influenza cases
 Pandemic (H1N1) 2009                                                                 4                               22
 Influenza A (Not Subtyped/No Subtype)                                               92                              192
 Influenza A (Seasonal H3)                                                           40                              288
 Influenza A** (Other)                                                                0                                2
 Influenza B                                                                          2                               11
 Influenza A and B                                                                    0                                0
 Total cases                                                                        138                              515
                                 ¦                                                    9                               28
 Institutional outbreaks
 So urce: On tario Ministry of Health and Lo ng -T erm Care, in teg rated Pub lic Health In fo rm atio n System (iPH IS), extra cted
 [01/04/2011].
 * The week that the diagnosing health unit was first notified of the cases episode.
 †
     Lab-confirmed cases include all reports of sporadic influenza cases and a subset of new outbreak associated cases.

 * * Includes indeterminate, untypeable and other subtypes.
 ¦This reflects the number of respiratory outbreaks confirmed to be caused by influenza during the week of interest.




Weekly Influenza Bulletin                                            Data as of: 05/01/11                                              1 of 13
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Surveillance Unit                                                                                            2010/11 Season

                                             Weekly Influenza Bulletin - continued


 Table 2. New lab-confirmed influenza cases reported in week 52 compared to the
 cumulative number of lab-confirmed influenza cases for the season to date and the 5-yr
 mean (2004/05 - 2008/09) by age group.


 Age group (years)                      Number of cases (%)                            Number of cases (%) season to date*

                                                                                                                         5-year mean
                                                 Week 52                                  2010/11
                                                                                                                      (2004/05 - 2008/09)
 <1                                                  5 (4)                                    23 (4)                         13 (16)
 1 to 4                                            12 (9)                                     65 (13)                           17 (21)
 5 to 14                                             3 (2)                                    29 (6)                            11 (13)
 15 to 24                                            2 (1)                                    10 (2)                              5 (6)
 25 to 44                                            9 (7)                                    68 (13)                           13 (16)
 45 to 64                                          15 (11)                                    56 (11)                             8 (10)
 65+                                               92 (67)                                  264 (51)                            14 (17)
 Total†                                          138 (100)                                  515 (100)                           81 (100)
 Source: Ontario Mini str y of Health and Long-Term Care, integrated Public Health Information System (iPHIS), extracted [01/04/2011].

 * All cases reported since September 1st of each season.
 †
     The total for season to date may fluctuate as missing ages prevent classification of cases in their week of report. Percentages are rounded up.

 Note: All cases from the 2009/10 influenza season were excluded f rom this table as the pH1N1 pandemic was not comparable to a typical flu
 season.


Influenza Subtype(s):
To date, Toronto influenza A cases that have been subtyped by the National
Microbiology Laboratory (NML) have been antigenically characterized as
A/Perth/16/2009-like (H3N2) and Pandemic H1N1 A/California/07/2009-like (H1N1),
which are both components included in the 2010/11 influenza trivalent vaccine. To
date, no Toronto influenza B cases have been subtyped.




Weekly Influenza Bulletin                                          Data as of: 05/01/11                                                            2 of 13
Communicable Disease                                                                                      Weekly Influenza Bulletin
Surveillance Unit                                                                                                  2010/11 Season

                                                  Weekly Influenza Bulletin - continued

  Table 3. Summary of new and cumulative influenza hospitalizations and deaths, by virus type. Reported
  week 52* (December 26, 2010 to January 01, 2011) and season to date (September 01, 2010 to January
  01, 2011).
                                                                                                             §                                         ‡
                                                                                 Hospitalizations                                               D eaths
                                                                           Week 52                Season to date                  Week 52             Season to date
                         †
  Lab-confirmed influenza cases
  Pandemic (H1N1) 2009                                                           0                          3                           0                      0
  Influenza A (Not Subtyped/No Subtype)                                          0                         20                           0                      2
  Influenza A (Seasonal H3)                                                      1                         56                           1                      2
  Influenza A** (Other)                                                          0                          0                           0                      0
  Influenza B                                                                    0                          0                           0                      0
  Influenza A and B                                                              0                          0                           0                      0
  Total Lab-confirmed influenza cases                                            1                         79                           1                      4
  Non Lab-confirmed influenza c ases                                             8                         30                           1                      7
  Total cases                                                                    9                        109                           2                      11
  So urce: On tario Ministry o f H ealth and Lo ng -Term Care, in teg rated Pu blic Health Informatio n Syste m (iPH IS), extrac ted [01/04/2011 ].


  *The week that the diagnosing health unit was first not ified of the cases episode.
  §
   Hospitalizations include both lab-confirmed cases and those with ILI who may have first been reported or ill in previous weeks, but f or whom hospitalization
  status is only being reported during this report week.
  ‡
   Newly reported deaths (among sporadic, outbreak associated or ILI cases) may include deaths occurring during this report week and/or deaths which had been
  reported as new cases/ILI in previous weeks, but who were not deceased when they were originally reported as a case.
  †
      Lab-confirmed cases include all reports of sporadic influenza cases and a subset of new outbreak associated cases.
  ** Includes indeterminate, untypeable and other subtypes.




Vaccination Rates:
The influenza vaccination rate for all laboratory confirmed reported cases with
vaccination history (N=86) was 16%.




Weekly Influenza Bulletin                                             Data as of: 05/01/11                                                                 3 of 13
Communicable Disease                                                                                              Weekly Influenza Bulletin
Surveillance Unit                                                                                                          2010/11 Season


                                                  Weekly Influenza Bulletin - continued


                       Figure 1. Rate* of reported lab-confirmed influenza cases by episode week†
                         and age group‡ (years). Toronto, September 01, 2010 to January 1, 2011
        30.0

                                <1
                                1-4
                                5-14
                                15-24
                                25-44
        25.0
                                45-64
                                65+




       n 20.0
       o
       i
       t
       a
       l
       u
       p
       o
       p
       0
       0
       0
       ,
       0
       0
       1 15.0
       r
       e
       p
       s
       e
       s
       a
       c
       f
       o
       r
       e
       b
       m
       u 10.0
       N




          5.0




          0.0
                  35       36         37     38      39       40       41       42      43       44       45       46       47      48        49   50   51   52
                                                                                     Episode week
      Source: Ontario Ministry of Health and Long-Term Care, integrated Public Health Information System (iP HIS ), extracted [01/04/2011].
      *Cases per 100,000 population. Population source: Statistics Canada [October 2009 postcensal estimates].
      †The episode week is the week closest to the date when symptoms fi rst appear.
      ‡ Since September 1st, 2010 the age was not reported for one case.




Weekly Influenza Bulletin                                                   Data as of: 05/01/11                                                                  4 of 13
Communicable Disease                                                                                                                      Weekly Influenza Bulletin
Surveillance Unit                                                                                                                                  2010/11 Season


                                                                         Weekly Influenza Bulletin - continued

                                          Figure 2. Number and rate* of reported lab-confirmed influenza cases by age group.
                                                           Toronto, September 01, 2010 to January 1, 2011
                         300                                                                                                                                       80.0


                                                                Number of cases    Age-specific rate

                                                                                                                                                                   70.0
                         250


                                                                                                                                                                   60.0




                                                                                                                                                                          Number of cases per 100,000 population
                         200
                                                                                                                                                                   50.0
  Number of reported cases




                         150                                                                                                                                       40.0




                                                                                                                                                                   30.0
                         100


                                                                                                                                                                   20.0


                              50
                                                                                                                                                                   10.0




                               0                                                                                                                                   0.0



                                                                                                         Age group (years)


                             Source: Ontario Ministry of Health and Long-Term Care, integrated Public Health Information System (iPHIS), extracted [01/04/2011].
                             *Cases per 100,000 population. Population source: Statistics Canada [October 2009 postcensal estimates].




Weekly Influenza Bulletin                                                                              Data as of: 05/01/11                                               5 of 13
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Surveillance Unit                                                                                    2010/11 Season

                                       Weekly Influenza Bulletin - continued

INSTITUTIONAL OUTBREAKS

For the purposes of this report, institutions include: long-term care homes, acute care hospitals, chronic
care hospitals, special care facilities, retirement homes and rehabilitation hospitals in Toronto.

To-date, twenty-eight influenza outbreaks have been detected this season.

 Table 4: Cumulative number of influenza outbreaks* in institutions by region.
 Toronto, September 01, 2010 to January 1, 2011
                                                                                           Region
                                                                   East           North            South             West            Total
 Influenza type
    Type A                                                          13                8               3                4               28
    Type B                                                           0                0               0                0                0
    Type A and B                                                     0                0               0                0                0
 Total                                                              13                8               3                4               28
 Residents
    Affected                                                       139              120               10              44              313
    At risk                                                       1205              800              176              393             2574
    Attack rate (%)                                                (12)             (15)             (6)             (11)             (12)
 Staff
    Affected                                                        37               23               2               21               83
    At risk                                                       1132              768              305              381             2586
    Attack rate (%)                                                 (3)              (3)             (1)              (6)              (3)
 Related deaths                                                      5                3               0                1                9
 Related pneumonia                                                   5                5               0                0               10
 Related hospitalizations                                           18               15               0                7               40
 Source: Ontario Ministr y of Health and Long-Term Care, integrated Public Health Information System (iPHIS) & CDSU Outbreaks Database,
 extracted [01/04/ 2011].
 * Number of outbreaks since September 1, 2010.
 Please note due to an ongoing reconciliation process between iPHIS and the CDSU outbreaks database, changes in total outbreaks as well as
 corresponding data are to be expected.




Weekly Influenza Bulletin                                    Data as of: 05/01/11                                                            6 of 13
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Surveillance Unit                                                                                                        2010/11 Season

                                                                 Weekly Influenza Bulletin - continued


                                         Figure 3. Number of influenza outbreaks in institutions by onset week*.
                                                     Toronto, September 01, 2010 to January 1, 2011
                                8

                                         Influenza A


                                7        Influenza B




                                6
 Number of reported outbreaks




                                5



                                4



                                3



                                2



                                1



                                0
                                    35      36         37   38     39   40   41      42     43    44     45       46       47          48   49   50   51   52
                                                                                          Onset week

 Source: Ontario Ministry of Health and Long-Term Care, integrated Public Health Information System (iPHIS), extracted [01/04/2011].
 *Onset date is the date symptoms began for the outbreak's index case.




Weekly Influenza Bulletin                                                         Data as of: 05/01/11                                                     7 of 13
Communicable Disease                                                                                                       Weekly Influenza Bulletin
Surveillance Unit                                                                                                                   2010/11 Season


                                                                             Weekly Influenza Bulletin - continued


                                 Figure 4. Number of respiratory outbreaks in institutions by onset week* and by causative
                                               organism. Toronto, September 01, 2010 to January 1, 2011
                                  10
                                                 Combined outbreaks**
                                                 No organism identified
                                                 RSV - Respiratory Syncytial Virus
                                   9             Parainfluenza (all types)
                                                 Other Organisms
                                                 Influenza B
                                   8             Influenza A




                                   7
  Number of reported outbreaks




                                   6


                                   5


                                   4


                                   3


                                   2


                                   1


                                   0
                                       35   36      37           38           39     40   41      42    43     44     45   46   47   48   49   50   51   52
                                                                                                       Onset week
 Source: Ontario Ministry of Health and Long-Term Care, integrated Public Health Information System (iPHIS), extracted [01/04/2011].
 *Onset week is the week symptoms began for the outbreak's index case.
 **Combined outbreaks include outbreaks in which more than one non-influenza organism has been identified (e.g RSV and rhinovirus).




Weekly Influenza Bulletin                                                                      Data as of: 05/01/11                                      8 of 13
Communicable Disease                                                                                                Weekly Influenza Bulletin
Surveillance Unit                                                                                                            2010/11 Season

                                                  Weekly Influenza Bulletin - continued


                  Figure 5. Number of reported lab-confirmed influenza cases by episode week* .
                  Toronto, comparison of the current season and 5-yr mean (2004/05 to 2008/09).
     200
                       2010/2011 cases

     180               Historical mean and 95% confid ence intervals




     160


     140

    s
    e
    s
    a120
    c
    d
    e
    t
    r
    o
    p 100
    e
    r
    f
    o
    r
    e
    b 80
    m
    u
    N

      60


      40


      20


        0
                35       36       37        38        39        40     41        42       43       44        45       46       47       48           49   50   51   52
                                                                                          Episode week

 Source: Ontario Ministry of Health and Long-Term Care, integrated Public Health Information System (iPHIS), extracted [01/04/2011].
 *The episode week is the week closest to the date when symptoms first appear.
 Note: All cases from the 2009/10 influenza season were excluded from this graph as the pH1N1 pandemic was not comparable to a typical flu season.




Weekly Influenza Bulletin                                                    Data as of: 05/01/11                                                                   9 of 13
Communicable Disease                                                                                                           Weekly Influenza Bulletin
Surveillance Unit                                                                                                                       2010/11 Season

                                                                    Weekly Influenza Bulletin - continued

ILI Sentinel Physician Consultation Rate
The Influenza-like illness (ILI) consultation rate for Toronto sentinel physicians in week
52 (31 ILI per 1,000 visits) was higher than the rate in week 51 (23 ILI per 1,000 visits)
and lower than Ontario’s rate (105 per 1,000 visits) for week 52 (Figure 6).

                                                     Figure 6: ILI sentinel physician consultation rate, by week.
                                                             Toronto and Ontario, Week 35 to Week 52
                                120
                                                Toronto


                                                Ontario
                                100




                                80
   IlI cases per 1,000 visits




                                60




                                40




                                20




                                  0
                                      35   36        37   38   39   40    41       42       43        44   45   46   47   48   49   50   51   52
                                                                                               Week
   Note: The small numbers of sentienel physicians reporting in Toronto can make the ILI rates unstable.




Weekly Influenza Bulletin                                                                        Data as of: 05/01/11                              10 of 13
Communicable Disease                                                                                                                               Weekly Influenza Bulletin
Surveillance Unit                                                                                                                                           2010/11 Season

                                                                  Weekly Influenza Bulletin - continued

Absenteeism in Schools
Both school boards, the TDSB and TCDSB, were closed for the winter break in week 52
(Figure 7).

                                            Figure 7: Overall absenteeism rate all elementary schools by day. TDSB and
                                            TCDSB combined. September 13, to December 31, 2009-2010 and 2010-2011
                                      14%
                                                 2010/2011

                                                 2009/2010

                                      12%
  Proportion of students absent (%)




                                      10%



                                      8%



                                      6%



                                      4%



                                      2%



                                      0%



                                                                                                Date
 Toronto Public Health (TPH) receives all-cause student absenteeism data weekly from the Toronto District School Board (TDSB) and the Toronto Catholic District School Board
 (TCDSB) for all elementary schools. Data are received for the previous school week.
 Data for the week of September 07, 2010 to September 10, 2010 was unavailable due to a technical issue.




Weekly Influenza Bulletin                                                                       Data as of: 05/01/11                                                           11 of 13
Communicable Disease                                               Weekly Influenza Bulletin
Surveillance Unit                                                           2010/11 Season

                            For related influenza information visit:


                                               ONTARIO
Ministry of Health and Long-Term Care

The latest Ontario Influenza Bulletin can be viewed at the following site:
http://www.health.gov.on.ca/en/pro/programs/publichealth/flu/bulletins/2010/default.aspx

Ontario Agency for Health Protection and Promotion

The latest Laboratory Viruses Respiratory Surveillance Report can be viewed at the following site:
http://www.oahpp.ca/SRI%20Bulletin.php


                                         HEALTH CANADA

The latest Health Canada FluWatch can be viewed at the following site:
http://origin.phac-aspc.gc.ca/fluwatch/index-eng.php


                                          INTERNATIONAL

The latest WHO Influenza – update can be viewed at the following site:
http://www.who.int/csr/disease/influenza/en/index.html

The current WHO phase of pandemic alert for avian influenza H5N1 can be viewed at the following site:
http://www.who.int/csr/disease/avian_influenza/phase/en/index.html




Weekly Influenza Bulletin                   Data as of: 05/01/11                                     12 of 13
Communicable Disease                                                      Weekly Influenza Bulletin
Surveillance Unit                                                                  2010/11 Season

                            Influenza surveillance weeks, 2010/11 season
               Week number              Start                       End            Range
                       35             29-Aug-10                4-Sep-10          29Aug-04Sep
                       36              5-Sep-10               11-Sep-10          05Sep-11Sep
                       37             12-Sep-10               18-Sep-10          12Sep-18Sep
                       38             19-Sep-10               25-Sep-10          19Sep-25Sep
                       39             26-Sep-10                2-Oct-10          26Sep-02Oct
                       40              3-Oct-10                9-Oct-10           03Oct-09Oct
                       41             10-Oct-10               16-Oct-10           10Oct-16Oct
                       42             17-Oct-10               23-Oct-10           17Oct-23Oct
                       43             24-Oct-10               30-Oct-10           24Oct-30Oct
                       44             31-Oct-10                6-Nov-10          31Oct-06Nov
                       45              7-Nov-10               13-Nov-10          07Nov-13Nov
                       46             14-Nov-10               20-Nov-10          14Nov-20Nov
                       47             21-Nov-10               27-Nov-10          21Nov-27Nov
                       48             28-Nov-10                4-Dec-10          28Nov-04Dec
                       49              5-Dec-10               11-Dec-10          05Dec-11Dec
                       50             12-Dec-10               18-Dec-10          12Dec-18Dec
                       51             19-Dec-10               25-Dec-10          19Dec-25Dec
                       52             26-Dec-10                1-Jan-11          26Dec-01Jan
                       1               2-Jan-11                8-Jan-11          02Jan-08Jan
                       2               9-Jan-11               15-Jan-11          09Jan-15Jan
                       3              16-Jan-11               22-Jan-11          16Jan-22Jan
                       4              23-Jan-11               29-Jan-11          23Jan-29Jan
                       5              30-Jan-11                5-Feb-11          30Jan-05Feb
                       6               6-Feb-11               12-Feb-11          06Feb-12Feb
                       7              13-Feb-11               19-Feb-11          13Feb-19Feb
                       8              20-Feb-11               26-Feb-11          20Feb-26Feb
                       9              27-Feb-11                5-Mar-11          27Feb-05Mar
                       10              6-Mar-11               12-Mar-11          06Mar-12Mar
                       11             13-Mar-11               19-Mar-11          13Mar-19Mar
                       12             20-Mar-11               26-Mar-11          20Mar-26Mar
                       13             27-Mar-11                2-Apr-11          27Mar-02Apr
                       14              3-Apr-11                9-Apr-11           03Apr-09Apr
                       15             10-Apr-11               16-Apr-11           10Apr-16Apr
                       16             17-Apr-11               23-Apr-11           17Apr-23Apr
                       17             24-Apr-11               30-Apr-11           24Apr-30Apr
                       18              1-May-11                7-May-11          01May-07May
                       19              8-May-11               14-May-11          08May-14May
                       20             15-May-11               21-May-11          15May-21May
                       21             22-May-11               28-May-11          22May-28May
                       22             29-May-11                4-Jun-11          29May-04Jun
                       23              5-Jun-11               11-Jun-11          05Jun-11Jun
                       24             12-Jun-11               18-Jun-11          12Jun-18Jun
                       25             19-Jun-11               25-Jun-11          19Jun-25Jun
                       26             26-Jun-11                 2-Jul-11          26Jun-02Jul
                       27               3-Jul-11                9-Jul-11           03Jul-09Jul
                       28              10-Jul-11               16-Jul-11           10Jul-16Jul
                       29              17-Jul-11               23-Jul-11           17Jul-23Jul
                       30              24-Jul-11               30-Jul-11           24Jul-30Jul
                       31              31-Jul-11               6-Aug-11           31Jul-06Aug
                       32              7-Aug-11               13-Aug-11          07Aug-13Aug
                       33             14-Aug-11               20-Aug-11          14Aug-20Aug
                       34             21-Aug-11               27-Aug-11          21Aug-27Aug


Weekly Influenza Bulletin                    Data as of: 05/01/11                                13 of 13

								
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