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NPHS Weekly Influenza Surveillance Report by set6tyhsd

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									    NPHS Weekly Influenza Surveillance Report
    Wednesday 12 August 2009


Summary
    The clinical consultation rate for influenza in Wales reported through the GP
     Surveillance of Infections Scheme decreased during week 32 to 49.4 per 100,000 (from
     69.9 per 100,000 in week 31) this is above the baseline level threshold of 25
     consultations per 100,000 practice population and would be considered to be normal
     seasonal activity for the winter period.
    During week 32 (week ending 09/08/09), ten samples from sentinel GPs were submitted for
     virological testing (see table 2), one of which tested positive for influenza A(H1N1)v (patient
     aged 1 – 4yrs, from South Wales) and one tested positive for rhinovirus (patient aged 15 –
     24yrs from North Wales). Since week 25 (week ending 21/06/09), 55 samples have been
     submitted by sentinel GPs for testing (including nine from the Out of Hours Service), four of
     these samples have tested positive for swine influenza A(H1N1)v and four have tested
     positive for rhinovirus.
    As at 10am 12/08/09, 100 laboratory-confirmed cases of swine influenza A(H1N1)v have
     been reported by NPHS Wales Health Protection Teams in 20 LHB areas (table 3). Thirty-
     three of these cases have been admitted to hospital, 31 of whom have now been discharged.
    During week 31 (week ending 02/08/09) the RCGP influenza like illness rate for England
     decreased from 137.0 per 100,000 to 42.0 per 100,000, which is above the baseline
     threshold of 30 consultations per 100,000. In Northern Ireland the combined influenza and
     influenza like illness consultation rate increased from 130.4 per 100,000 to 142.5 per 100,000
     (thresholds have not yet been set). In Scotland the GP influenza consultation rate decreased
     slightly from 55 per 100,000 to 48.4 per 100,000, during week 31. Updates for UK countries
     are produced on a weekly basis each Thursday and are available from:
     http://www.hpa.org.uk/web/HPAweb&Page&HPAwebAutoListName/Page/1243928258560
    ECDC report that as of 28 July, the cumulative number of swine influenza cases in the EU
     and EFTA countries is 34,152 of which 12,470 have occurred in the UK. ECDC report that
     there have been 54 deaths throughout Europe attributed to swine influenza A(H1N1)v, 40 of
     these occurred in the UK, nine in Spain, one in Hungary, one in Belgium, one in France, one
     in Ireland and one in the Netherlands. Thirty of the 31 EU and EEA/EFTA countries have now
     reported cases of swine influenza A(H1N1)v. Latest data (week 31) from Euroflu, indicates
     most European countries are reporting moderate – low activity. Wales, England, Malta and
     Austria report widespread activity, Italy reports geographic spread at a regional level, all other
     countries report local/ sporadic/ no geographical spread. Pandemic influenza A(H1N1)v
     continues to be the dominant influenza virus, accounting for 76% of the 85 influenza A
     detections in European sentinel physician influenza A positive samples and 80% of the 2,032
     European non-sentinel physician influenza A positive samples. Latest European level
     surveillance data is published each Friday at 12pm on: http://www.euroflu.org/
    The rolling seven day consultation rate for influenza from the NPHS Wales Rapid
     Surveillance of Influenza using Audit+ (containing data submitted up to 12/08/09 from 72% of
     General Practices in Wales) has decreased compared to the rate reported 7 days ago (from
     89.0 per 100,000 to 55.3 per 100,000). Consultation rates are between 25 and 100 per
     100,000 in all 22 LHB areas in Wales.
    Data from the NPHS Wales Specialist Virology Centre indicate that out of 354 samples from
     patients with respiratory illness (from hospital and the community) submitted for testing
     between 20/07/09 – 11/08/09, 22 tested positive for influenza A(H1N1)v, 31 samples tested
     positive for rhinovirus, 6 samples tested positive for parainfluenza and two samples tested
     positive for RSV. This suggests that while influenza A(H1N1)v is the dominant influenza virus,
     other respiratory viruses are also presently in circulation.
    Daily influenza surveillance updates are available from the NPHS Wales Rapid Influenza
     Surveillance internet site: http://www.wales.nhs.uk/sites3/page.cfm?orgid=457&pid=38241




                                                 -1-
           Figure 1. Clinical consultation rate per 100,000 practice population in Welsh sentinel
           practices (as of 12/08/09).
           1
                                                                                                                                            1999 - 2000                                                                    2007 - 2008                                                                   2008 - 2009
                                                                        200

                                                                        180

                                                                        160


                                       Consultation rate per 100,000
                                                                                                                                                                                                                    Higher than average seasonal activity
                                                                        140

                                                                        120

                                                                        100
                                                                                                                                                                                                                      Normal seasonal activity
                                                                              80

                                                                              60

                                                                              40

                                                                              20                                                                                                                                                Baseline activity

                                                                                    0
                                                                                               40
                                                                                               42
                                                                                               44
                                                                                               46
                                                                                               48
                                                                                               50
                                                                                               52
                                                                                                2
                                                                                                4
                                                                                                6
                                                                                                8
                                                                                               10
                                                                                               12
                                                                                               14
                                                                                               16
                                                                                               18
                                                                                               20
                                                                                               22
                                                                                               24
                                                                                               26
                                                                                               28
                                                                                               30
                                                                                               32
                                                                                               34
                                                                                               36
                                                                                               38
                                                                                                                                                                                                                                                Week

Table 1. Age specific consultations (per 100,000) for influenza in Welsh sentinel
practices, week 27 2009 – week 32 2009 (as of 12/08/09).
                                                                                                                      Age                                       Week
                                                                                                                     group                                       27                                  28                                29                                     30                                 31                                     32
                                                                                                                                                                                                                                                                                                                                                                                                                Age specific
                                                                                                                      0-4                                        0.0                                34.8                              58.0                                  189.0                               92.1                                   86.6
                                                                                                                                                                                                                                                                                                                                                                                                                consultation rate
                                                                                                                     5 - 14                                      6.3                                18.4                               9.4                                  104.9                               56.4                                   43.4                                                     during week 32
                                                                                                                     15 - 24                                    11.7                                27.0                              66.7                                  109.6                              110.2                                   61.9                                                     were highest
                                                                                                                     25 - 34                                     9.2                                16.7                              57.9                                  129.2                              106.9                                   97.2                                                     among patients
                                                                                                                     35 - 44                                     7.5                                12.0                              40.5                                   91.2                               58.4                                   48.1                                                     aged 25 - 34 yrs
                                                                                                                     45 - 64                                     1.8                                17.2                              34.6                                   75.0                               74.2                                   37.9
                                                                                                                      65 +                                       1.9                                 1.9                               9.9                                   45.6                               24.7                                   19.3
                                                                                                                      Total                                      5.1                                15.8                              36.0                                   92.8                               69.9                                   49.4

Figure 2. Historical clinical consultation rate per 100,000 practice population in Welsh
sentinel practices (week 41 1996 – week 32 2009).

                                 450
                                                                                                                                                                                                                                                                                                                          Epidemic activity
                                 400
 Consultation rate per 100,000




                                 350

                                 300

                                 250                                                                                                                                                                                                                                                                    Higher than average
                                                                                                                                                                                                                                                                                                        seasonal (winter) activity
                                 200

                                 150

                                 100
                                                                                                                                                                                                                                                                                                                                    Normal seasonal
                                 50                                                                                                                                                                                                                                                                                                 activity (winter)

                                   0
                                                    October 1996
                                                                       April 1997
                                                                                    October 1997
                                                                                                   April 1998
                                                                                                                October 1998
                                                                                                                               April 1999
                                                                                                                                            October 1999
                                                                                                                                                           April 2000
                                                                                                                                                                        October 2000
                                                                                                                                                                                       April 2001
                                                                                                                                                                                                    October 2001
                                                                                                                                                                                                                   April 2002
                                                                                                                                                                                                                                 October 2002
                                                                                                                                                                                                                                                April 2003
                                                                                                                                                                                                                                                             October 2003
                                                                                                                                                                                                                                                                            April 2004
                                                                                                                                                                                                                                                                                         October 2004
                                                                                                                                                                                                                                                                                                        April 2005
                                                                                                                                                                                                                                                                                                                     October 2005
                                                                                                                                                                                                                                                                                                                                    April 2006
                                                                                                                                                                                                                                                                                                                                                 October 2006
                                                                                                                                                                                                                                                                                                                                                                April 2007
                                                                                                                                                                                                                                                                                                                                                                             October 2007
                                                                                                                                                                                                                                                                                                                                                                                            April 2008
                                                                                                                                                                                                                                                                                                                                                                                                         October 2008
                                                                                                                                                                                                                                                                                                                                                                                                                        March 2009




                                                                                                                                                                                                                                -2-
Enhanced virological surveillance for influenza and respiratory viruses
 Table 2. Specimens submitted for virological surveillance (as at 12/08/09, by week of
 sample collection, combined results from GP sentinel surveillance and Out of Hours
 GP sentinel surveillance) .

Week Specimens Specimens                              Positive identifications
     submitted   tested               influenza A     influenza
                                                                  RSV parainfluenza rhinovirus
                                  Total A A(H1N1)v*        B
  26           3              3      0          0          0       0           0        0
  27           4              4      1          1          0       0           0        0
  28          10             10      0          0          0       0           0        0
  29          13             13      1          1          0       0           0        1
  30           4              4      0          0          0       0           0        0
  31          11             11      1          1          0       0           0        2
  32          10             10      1          1          0       0           0        1
 Total        55             55      4          4          0       0           0        4
* swine influenza A(H1N1)v
During week 32 (week ending 09/08/09) ten samples were submitted by sentinel GPs for testing,
one of which tested positive for swine influenza A(H1N1)v and one of which tested positive for
rhinovirus. Since week 26 (22 Jun 2009) 55 samples have been received and tested from sentinel
GPs (including nine Out of Hours GP Service sample). Four samples have tested positive for
influenza A and were further identified as swine influenza A(H1N1)v and four samples have
tested positive for rhinovirus.




                                              -3-
Summary of Confirmed swine influenza A(H1N1)v cases in Wales
    Table 3. Confirmed Swine influenza A(H1N1)v cases reported to NPHS Wales, as at
    12/08/09, by LHB area of residence.

                                LHB                           Laboratory
                                                            confirmed cases
                                Anglesey                            2
                                Blaenau Gwent                       2
                                Bridgend                            1
                                Caerphilly                          7
                                Cardiff                            26
                                Carmarthen                          3
                                Ceredigion                          3
                                Conwy                               2
                                Denbighshire                        4
                                Merthyr                             5
                                Monmouthshire                       5
                                Neath Port Talbot                   2
                                Newport                            16
                                Pembrokeshire                       2
                                Powys                               4
                                RCT                                 3
                                Swansea                             8
                                Torfaen                             2
                                Vale of Glamorgan                   2
                                Wrexham                             1
                                Total                             100
    Tables 4 and 5. Confirmed Swine influenza A(H1N1)v cases reported to NPHS Wales,
    as at 12/08/09, by reporting week (Table 4) and age group (Table 5)

4       Week      Laboratory         N umber       5     Age group        Laboratory
       notified confirmed cases    Hospitalised                         confirmed cases
         22             1                0                    <1                2
         23             1                0                   1-4                7
         24             1                0                   5-14              12
         25             2                0                  15-24              42
         26            19                1                  25-34              13
         27            34                0                  35-44               7
         28             6                5                  45-64              14
         29            13                9                  65-74               3
         30             8                8                   75+                0
         31             6                2                  Total             100
         32             8                7
         33             1                1
        Total         100               33

As at 12/08/2009 there have been 100 laboratory confirmed cases reported to NPHS Wales.
Thirty-three of these cases were hospitalised, 31 of whom have now been discharged. The age
group currently with the highest numbers of confirmed cases is 15 - 24 years. Confirmed cases
have been reported in 20 LHB areas in Wales. These figures represent only laboratory confirmed
cases which are reported directly to NPHS Wales. Actual numbers of cases are likely to be higher
and during the treatment phase of the pandemic most cases will not be reported directly to NPHS
Wales or virologically confirmed. The laboratory confirmed hospitalised patients in tables 3 - 5 are
a subset of the total number of patients who have been admitted to hospital with influenza like
symptoms.




                                               -4-
Latest data from the Welsh Assembly Government’s Service Delivery and Performance
Management Directorate indicate that as at 12/09/08 there were Eight patients across Wales
hospitalized in connection with swine influenza, three of whom suffer from identified co-
morbidities or underlying conditions, with two patients in critical care (although swine influenza
A(H1N1)v has not been confirmed in either of these cases).

Rapid surveillance of influenza using Audit+
                  Figure 3. Rapid surveillance of influenza in Wales using Audit+, clinical consultation
                  rate, rolling 7 day rate as at 12/08/09.
                                  400

                                  350
  Consultation rate per 100,000




                                  300

                                  250

                                  200

                                  150

                                  100

                                  50

                                    0
                                        01/05/2009
                                                     05/05/2009
                                                                  09/05/2009
                                                                  13/05/2009
                                                                               17/05/2009
                                                                                            21/05/2009
                                                                                            25/05/2009
                                                                                                         29/05/2009
                                                                                                                      02/06/2009
                                                                                                                      06/06/2009
                                                                                                                                   10/06/2009
                                                                                                                                                14/06/2009
                                                                                                                                                18/06/2009
                                                                                                                                                             22/06/2009
                                                                                                                                                                          26/06/2009
                                                                                                                                                                          30/06/2009
                                                                                                                                                                                       04/07/2009
                                                                                                                                                                                                    08/07/2009
                                                                                                                                                                                                                 12/07/2009
                                                                                                                                                                                                                 16/07/2009
                                                                                                                                                                                                                              20/07/2009
                                                                                                                                                                                                                                           24/07/2009
                                                                                                                                                                                                                                           28/07/2009
                                                                                                                                                                                                                                                        01/08/2009
                                                                                                                                                                                                                                                                     05/08/2009
                                                                                                                                                                                                                                                                     09/08/2009
                                                                                                                                                                                                                                                                                  13/08/2009
                                                                                                                                                                                                                                                                                               17/08/2009
                                                                                                                                                                                                                                                                                               21/08/2009
                                                                                                                                                                                                                                                                                                            25/08/2009
                                                                                                                                                                                                                                                                                                                         29/08/2009
                  Figure 4. Rapid surveillance of influenza in Wales LHB influenza consultation rates
                  (per 100,000 practice population), rolling 7 day rate as at 12/08/09.




Surveillance for influenza consultations in Wales using Audit+, shows the rolling seven day
consultation rate for influenza has decreased over the last week (see figure 3), with most LHB
areas showing similar trends. As at 12/08/09 the consultation rate for Wales as a whole was 55.3
per 100,000 (compared to 89.02 per 100,000 reported seven days ago). Consultation rates in all
LHB areas exceed 25 per 100,000 (see figure 4), no LHB area has a consultation rate exceeding
100 per 100,000 (compared to five LHB areas in the preceding week). Consultation rates appear

                                                                                                                                                                          -5-
highest in South East Wales. Rolling 7 day age specific consultation rates have decreased in all
age groups over the last seven days, but are highest in children aged four years and under (figure
5).


      Figure 5. Rapid surveillance of influenza in Wales LHB influenza age group specific
      consultation rates (per 100,000 practice population), rolling 7 day rate as at 12/08/09.



                                            400

                                            350
            Consultation rate per 100,000




                                            300

                                            250

                                            200

                                            150

                                            100

                                             50

                                              0
                                                                           <01                                  1-4                                      5-14                                        15-44                                45-64                                   65-75                                       75+
                                                                                                                                                                                        Age group


                                                                                                                                                                                                                       1
      Figure 6. Influenza related calls to NHS direct Wales (as a percentage of total calls)
      to week 32 2009 (as of 12/08/09).

                                            60.0

                                            50.0
    Percentage




                                            40.0

                                            30.0

                                            20.0

                                            10.0

                                             0.0
                                                                                                    17-Jul-06



                                                                                                                            06-Nov-06




                                                                                                                                                                23-Apr-07

                                                                                                                                                                            18-Jun-07

                                                                                                                                                                                         13-Aug-07

                                                                                                                                                                                                      08-Oct-07




                                                                                                                                                                                                                                                                  14-Jul-08



                                                                                                                                                                                                                                                                                          03-Nov-08




                                                                                                                                                                                                                                                                                                                              20-Apr-09

                                                                                                                                                                                                                                                                                                                                          15-Jun-09
                                                   06-Dec-05

                                                               31-Jan-06

                                                                            27-Mar-06

                                                                                        22-May-06



                                                                                                                11-Sep-06



                                                                                                                                        01-Jan-07

                                                                                                                                                    26-Feb-07




                                                                                                                                                                                                                  03-Dec-07

                                                                                                                                                                                                                              28-Jan-08

                                                                                                                                                                                                                                          24-Mar-08

                                                                                                                                                                                                                                                      19-May-08



                                                                                                                                                                                                                                                                              08-Sep-08



                                                                                                                                                                                                                                                                                                      29-Dec-08

                                                                                                                                                                                                                                                                                                                  23-Feb-09




                                                                                                                                                                            Week commencing

During week 32, the percentage of total calls to NHS Direct Wales which were influenza related
decreased to 29.8% (figure 6).
1
 Data supplied by Health Statistics and Analysis Unit, Welsh Assembly Government.
Flu related calls are the sum of calls recorded as 'cold/flu', 'cough', 'headache', 'fever' and 'sore throat'.




                                                                                                                                                                                 -6-
Links:

NPHS Wales Swine influenza webpage:
http://www.wales.nhs.uk/sites3/page.cfm?orgid=457&pid=37250
HPA Swine influenza webpage:
http://www.hpa.org.uk/webw/HPAweb&HPAwebStandard/HPAweb_C/1240732818210?p=12
31252394302
NICE influenza antiviral usage guidance:
http://www.nice.org.uk/Guidance/TA158
Wales influenza information:
http://www.wales.nhs.uk/sites3/page.cfm?orgid=457&pid=27922
England influenza information:
http://www.hpa.org.uk/infections/topics_az/influenza/seasonal/default.htm
Scotland influenza information:
http://www.hps.scot.nhs.uk/search/atozdetail.aspx?subject=95
Northern Ireland influenza information:
http://www.cdscni.org.uk/publications/default.asp
European Centre for Communicable Disease:
http://ecdc.europa.eu/
European influenza information:
http://www.euroflu.org/
Avian influenza in the UK:
http://www.hpa.org.uk/infections/topics_az/influenza/avian/default.htm
Avian influenza/ pandemic information:
http://www.who.int/csr/disease/avian_influenza/en/index.html




                                           -7-

								
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