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Weekly influenza surveillance overview - 30 December 2010 (ECDC, extract, edited)

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  • Weekly influenza surveillance overview - 30 December 2010 (ECDC, extract, edited)

    Weekly influenza surveillance overview - 30 December 2010 (ECDC, extract, edited)


    [Source: European Centre for Disease Prevention and Control (ECDC), full PDF document (LINK). Extract, edited.]

    SURVEILLANCE REPORT

    Weekly influenza surveillance overview - 30 December 2010


    Main surveillance developments in week 51/2010 (20 Dec 2010 ? 26 Dec 2010)

    This first page contains the main developments of this week and can be printed separately or together with the more detailed information following.
    • Reporting of influenza is less complete over Weeks 51 and 52 due to the holiday period which reduces consulting rates, reporting to national centres and onto ECDC.
    • In addition there is the effect of school closures which seems to reduce transmission of A(H1N1) 2009.
    • Sixteen countries experienced influenza activity of low intensity and four countries reported medium intensity.
    • Three countries (Belgium, France and Portugal) reported widespread activity and six countries reported increasing trends.
    • A total of 642 influenza viruses were detected during week 51/2010. Of these detections, 65% were type A and 35% were type B.
    • The percentage of sentinel specimens testing positive for influenza virus (33.5%) was lower than in the previous week (39.4%), but this decline may reflect the discontinuity in reporting.
    • Fifty-two SARI cases were reported by Belgium and Romania. Of eight cases in this latter country, two were related to influenza infection.


    Sentinel surveillance of influenza-like illness (ILI)/ acute respiratory infection (ARI):

    Four western countries (Belgium, Portugal, Spain and UK (Northern Ireland)) reported medium intensity of influenza activity. Belgium, France and Portugal reported widespread activity and sporadic activity was reported by nine countries.


    Virological surveillance:

    In week 51/2010, eighteen countries reported virological data. Sentinel physicians collected 570 specimens with a slightly decreased percentage (33.5%) testing positive for influenza virus compared with the previous week (39.4%).


    Hospital surveillance of severe acute respiratory infection (SARI):

    Fifty-two SARI cases were reported by Belgium and Romania. Of the eight cases from the latter country, two were related to A(H1N1) pandemic infection.


    Sentinel surveillance (ILI/ARI) - Weekly analysis ? epidemiology

    Sixteen countries experienced influenza activity of low intensity and four countries (Belgium, Portugal, Spain and the UK (Northern Ireland)) reported medium intensity. (Table 1, Map 1).

    Three countries, Belgium, France and Portugal, reported widespread activity.

    Regional activity was reported by the Netherlands and local activity by Spain.

    Sporadic activity was reported by nine countries, while five countries (Austria, Bulgaria, Greece, Poland and Romania) reported no influenza activity (Table 1, Map 2).

    In week 51/2010, six countries (Belgium, Estonia, France, Portugal, Spain and the UK (Northern Ireland)) reported increasing trends, nine countries reported stable trends and four countries (Bulgaria, Hungary, Poland and Romania) reported a decreasing trend (Table 1, Map 2).


    Country comments
    • Sweden:
      • very few health centres have reported this week due to the Christmas holidays.
    • UK (England):
      • Very low return this week due to holiday period.

    (...)


    Table 1: Epidemiological and virological overview by country, week 51/2010

    [Country - Intensity - Geographic spread - Trend - No. of sentinel swabs - Dominant type - Percentage positive* - ILI per 100 000 - ARI per 100 000]
    • Austria - Low - No activity - Unknown (no information available) - 8 - None - 25.0 - ... - 19.8
    • Belgium - Medium - Widespread - Increasing - 35 - A - 80.0 - 267.2 - 1982.0
    • Bulgaria - Low - No activity - Decreasing - ... - None - 0.0 - ... - 736.2
    • Cyprus - Low - Sporadic - Stable - ... - ... - 0.0 - ...* - ...*
    • Czech Republic - Low - Sporadic - Stable - ... - ... - 0.0 - 23.7 - 833.6
    • Denmark - Low - Sporadic - Stable - 7 - None - 14.3 - 83.1 - ...
    • Estonia - Low - Sporadic - Increasing - 21 - None - 23.8 - 7.3 - 268.6
    • Finland - ... - ... - ... - ... - ... - 0.0 - ... - ...
    • France - Low - Widespread - Increasing - 83 - None - 34.9 - ... - 2158.6
    • Germany - ... - ... - ... - 39 -None - 28.2 - ... - ...
    • Greece - Low - No activity - Stable - 6 - None - 0.0 - 61.4 - ...
    • Hungary - Low - Sporadic - Decreasing - 27 - A, H1v - 3.7 - 75.4 - ...
    • Iceland - ... - ... - ... - ... - ... - 0.0 - ... - ...
    • Ireland - ... - ... - ... - ... - ... - 0.0 - ... - ...
    • Italy - ... - ... - ... - 46 - A - 28.3 - ... - ...
    • Latvia - Low - Sporadic - Stable - 0 - A, H1v - 0.0 - 1.8 - 733.4
    • Lithuania - Low - Sporadic - Stable - ... - ... 0.0 - 4.8 - 428.4
    • Luxembourg - ... - ... - ... - 13 - ... - 38.5 - ...* - ...*
    • Malta - ... - ... - ... - 10 - A, H1N1 - 40.0 - ... - ...
    • Netherlands - Low - Regional - Stable - 10 - None - 30.0 - 23.4 - ...
    • Norway - ... - ... - ... - 17 - B - 41.2 - ... - ...
    • Poland - Low - No activity - Decreasing - 3 - None - 0.0 - 52.2 - ...
    • Portugal - Medium - Widespread - Increasing - 4 -None - 100.0 - 55.1 - ...
    • Romania - Low - No activity - Decreasing - 37 - None - 0.0 - 17.6 - 735.5
    • Slovakia - ... - ... - ... - 3 - None - 0.0 - ... - ...
    • Slovenia - Low - Sporadic - Stable - ... - ... - 0.0 - 1.5 - 1378.1
    • Spain - Medium - Local - Increasing - 151 - swoAH1N1 - 43.7 - 82.4 - ...
    • Sweden - Low - Sporadic - Stable - 24 - None - 8.3 - 10.0 - ...
    • UK - England - ... - ... - ... - ... - ... - 0.0 - ... - ...
    • UK - Northern Ireland - Medium - Local - Increasing - 26 - swoAH1N1 - 38.5 - 99.4 - 691.5
    • UK - Scotland - ... - ... - ... - ... - ... - 0.0 - ... - ...
    • UK - Wales - ... - ... - ... - ... - ... - 0.0 - ... - ...
    • Europe - ... - ... - ... - 570 - ... - 33.5 - ... - ...

    (*) Incidence per 100 000 is not calculated for these countries as no population denominator is provided.

    Note: Liechtenstein is not reporting to the European Influenza Surveillance Network


    Description of the system

    This surveillance is based on nationally organised sentinel networks of physicians, mostly general practitioners (GPs), covering at least 1?5% of the population in their countries. All EU/EEA Member States (except Liechtenstein) are participating. Depending on their country?s choice, each sentinel physician reports the weekly number of patients seen with influenza-like illness (ILI), acute respiratory infection (ARI) or both to a national focal point. From the national level, both numerator and denominator data are then reported to the European Surveillance System (TESSy) database. Additional semi-quantitative indicators of intensity, geographic spread and trend of influenza activity at the national level are also reported.


    Virological surveillance - Weekly analysis ? virology

    In week 51/2010, 20 countries and the UK (Northern Ireland) reported virological data.

    Sentinel physicians collected 570 specimens with a decreasing percentage (33.5%) testing positive for influenza virus compared with the previous week (39.4%) (Tables 1 and 2, Figure 3).

    In addition, 451 non-sentinel source specimens (i.e. specimens collected for diagnostic purposes in hospitals) were reported positive for influenza virus.

    Of the 642 influenza viruses detected during week 51/2010, 420 (65%) were type A and 222 (35%) were type B.

    The A(H1N1) 2009 virus was reported as dominant in Belgium, Hungary, Italy, Latvia, Malta, Spain and UK (Northern Ireland) while influenza B virus was dominant in Norway.

    Of the 312 sentinel influenza A viruses that were sub-typed, 302 (97%) were A(H1N1) 2009 and 10 (3%) were A(H3) viruses (Table 2).

    Since week 40/2010, of the 3 122 influenza detections in sentinel and non-sentinel specimens, 2 130 (68%) were type A and 992 (32%) were type B influenza viruses. Of 1 245 influenza A viruses sub-typed, 1 149 (92%) were A(H1N1) 2009 and 96 (8%) were A(H3) viruses (Table 2). Trends of virological detections since week 40/2010 are shown in Figures 1?3.

    Since week 40/2010, 180 influenza viruses from sentinel and non-sentinel specimens have been characterised antigenically (Figure 4): 95 as A/California/7/2009 (H1N1)-like; 25 as A/Perth/16/2009 (H3N2)-like; 54 as B/Brisbane/60/2008-like (Victoria lineage) and six as B/Florida/4/2006-like (Yamagata lineage).

    More details on circulating viruses can be found in the report prepared by the Community Network of Reference Laboratories (CNRL) coordination team.

    In week 51/2010, respiratory syncytial virus detections apparently decreased, but it is impossible to estimate the trend as only 18 countries and the UK (Northern Ireland) reported in week 51/2010, compared with 26 countries the previous week (Figure 5).

    In terms of antiviral resistance since week 40/2010, a total of 185 influenza A(H1N1) 2009 viruses and six influenza B viruses have been tested for susceptibility to neuraminidase inhibitors.

    Data were provided for either single location (e.g. H275Y only) or multiple location substitution analysis (full sequencing) and/or phenotyping (IC50 determination) and should be interpreted in this context (Table 2).

    All but two viruses were sensitive to both oseltamivir and zanamivir.

    Two A(H1N1) 2009 viruses from the UK had the H275Y substitution known to confer resistance to oseltamivir while retaining susceptibility to zanamivir. Both viruses were from patients who had not been treated with oseltamivir.


    Table 2: Weekly and cumulative influenza virus detections by type, subtype and surveillance system, weeks 40/2010?51/2010

    [Virus Type/Subtype - Current Period: Sentinel - Non-sentinel / Season: Sentinel - Non-sentinel]
    • Influenza A - 133 - 287 / 757 - 1373
      • A (pandemic H1N1) - 87 - 215 / 616 - 533
      • A (subtyping not performed) - 41 - 67 / 84 - 601
      • A (not subtypable) - 0 - 0 / 0 - 0
      • A (H3) - 5 -5 / 57 - 39
      • A (H1) - 0 - 0 / 0 - 0
    • Influenza B - 58 - 164 / 399 - 593
    • Total Influenza - 191 - 451 / 1156 - 1966


    Note: A(H1)2009, A(H3) and A(H1) includes both N-subtyped and non-N-subtyped viruses

    (...)


    Table 3: Antiviral resistance by influenza virus type and subtype, weeks 40/2010?51/2010

    [Virus type and subtype - Resistance to neuraminidase inhibitors: Oseltamivir (Isolates tested - Resistant n (%)) - Zanamivir (Isolates tested - Resistant n (%)) - Resistance to M2 inhibitors: (Isolates tested - Resistant n (%))]
    • A(H3N2) - ( 0 - 0 ) - ( 0 - 0 ) - ( 0 - 0 )
    • A(H1N1) - ( 0 - 0 ) - ( 0 - 0 ) - ( 0 - 0 )
    • A(H1N1)2009 - ( 185 - 2 (1.1) ) - ( ... - 0 ) - ( 0 - 0 )
    • B - ( 6 - 0 ) - ( 6 - 0 ) - ( NA* - NA* )

    (*) NA - not applicable, as M2 inhibitors do not act against influenza B viruses

    Data were provided for either single location (e.g. H275Y only) or multiple location substitution analysis (full sequencing) and/or phenotyping (IC50 determination) and should be interpreted in this context.

    (...)


    Description of the system

    According to the nationally defined sampling strategy, sentinel physicians take nasal or pharyngeal swabs from patients with influenza-like illness (ILI), acute respiratory infection (ARI) or both and send the specimens to influenza-specific reference laboratories for virus detection, (sub-)typing, antigenic or genetic characterisation and antiviral susceptibility testing.

    For details on the current virus strains recommended by WHO for vaccine preparation click here.


    Hospital surveillance ? severe acute respiratory infection (SARI) - Weekly analysis ? SARI

    During week 51/2010, 44 SARI cases were reported by Belgium and eight cases by Romania (Table 5).

    Two cases in Romania were related to influenza A(H1N1) pandemic infection.

    Of 49 cases, 21 (43%) were in individuals under two years old and the gender ratio (male/female) was one.

    Of ten patients with available information, two were vaccinated and of 52 patients for whom information was available, 43 had no underlying conditions.

    Of 52 patients, 26 needed oxygen therapy and only one received oseltamivir as antiviral treatment.

    In Romania, all eight cases presented an acute respiratory distress symptom.

    Since week 40/2010, 507 SARI cases have been reported by four countries with five fatalities. In documented cases, 19 were infected with A(H1N1) 2009 virus, one with A(H3N2) and three with influenza B virus (table 6).


    Table 4: Cumulative number of SARI cases, weeks 40/2010 ? week 51/2010

    [Country - Number of cases - Incidence of SARI cases per 100,000 population - Number of fatal cases reported - Incidence of fatal cases per 100,000 population - Estimated population covered]
    • Belgium - 406 - ... - ... - ... - ...
    • Spain - 23 - ... - 2 - ... - ...
    • Portugal - 5 - ... - ... - ... - ...
    • Romania - 71 - 1.11 - 3 - 0.05 - 6.413.821
    • Slovakia - 2 - ... - ... - ... - ...
    • Total - 507 - ... - 5 - ... - 6.413.821

    (...)

    Table 5: Number of SARI cases by age and gender, week 51/2010

    [Age groups - Male - Female - Unknown]
    • Under 2 - 13 - 8 - 1
    • 2-17 - 10 - 12 - 1
    • 18-44 - 2 - 1 - ...
    • 45-59 - ... - 1 - ...
    • >=60 - ... - 2 - 1
    • Total - 25 - 24 - 3


    Table 6: Number of SARI cases by influenza type and subtype, week 51/2010

    [Virus type/subtype - Number of cases during current week - Cumulative number of cases since the start of the season]
    • Influenza A - ... - 26
      • A (H1) 2009 - ... - 19
      • A(subtyping not performed) - ... - 6
      • A(H3) - ... - 1
      • A(H1) - ... - ...
      • A(H5) - ... - ...
    • Influenza B - ... - 3
    • Unknown - 50 - 450
    • Total - 52 - 507


    Table 7: Number of SARI cases by antiviral treatment, week 51/2010

    [Antiviral treatment - Number of patients who received prophylaxis - Number of patients who received anti-viral treatment]
    • Oseltamivir - ... - 1
    • Unknown - 44 - 44
    • None - 8 - 7
    • Total 52 - 52


    Table 8: Number of SARI cases by level of care and respiratory support, week 51/2010

    [Respiratory support - ICU - Inpatient ward - Other - Unknown]
    • No respiratory support necessary - ... - ... - 26 - ...
    • Oxygen therapy - 1 - 5 - 15 - ...
    • Ventilator - 5 - ... - ... - ...


    Table 9: Number of SARI cases by vaccination status, week 51/2010

    [Vaccination Status - Number Of Cases - Percentage of cases]
    • Not vaccinated - 8 - 15
    • Seasonal vaccination - 2 - 3.8
    • Unknown - 42 - 80.8
    • TOTAL - 52

    (...)


    Table 10: Number of underlying conditions in SARI cases by age group, week 51/2010

    [Underlying condition/risk factor - Infant below 2 years - 2-17 years - 18-44 years - 45-59 years - >=60 years]
    • Chronic heart disease - 1 - ... - ... - ... - 1
    • HIV/other immune deficiency - ... - ... - ... - ... - 1
    • Liver-related condition - ... - ... - ... - 1 - ...
    • No underlying condition - 20 - 20 - 2 - ... - 1
    • Other (please specify separately) - 1 - 3 - ... - ... - ...
    • Obesity (BMI between 30 and 40) - ... - ... - 1 - ... - ...


    Table 11: Additional clinical complications in SARI cases by age group, week 51/2010

    [Additional clinical complications - Infant below 2 years - 2-17 years - 18-44 years - 45-59 years - >=60 years]
    • Acute respiratory distress syndrome - 3 - 2 - 1 - 1 - 1
    • Unknown - 19 - 21 - 2 - ... - 2


    The report text was written by an editorial team at the European Centre for Disease Prevention and Control (ECDC): Eeva Broberg, Flaviu Plata, Phillip Zucs and Ren? Snacken. The bulletin text was reviewed by the Community Network of Reference Laboratories for Human Influenza in Europe (CNRL) coordination team: Adam Meijer, Rod Daniels, John McCauley and Maria Zambon. On behalf of the EISN members the bulletin text was reviewed by Bianca Snijders (RIVM Bilthoven, The Netherlands) and Thedi Ziegler (National Institute for Health and Welfare, Finland).

    Maps and commentary used in this Weekly Influenza Surveillance Overview (WISO) do not imply any opinions whatsoever of ECDC or its partners on the legal status of the countries and territories shown or concerning their borders.

    All data published in the WISO are up-to-date on the day of publication. Past this date, however, published data should not be used for longitudinal comparisons as countries tend to retrospectively update their numbers in the database.

    ? European Centre for Disease Prevention and Control, Stockholm, 2010

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