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EuroFlu - Weekly Electronic Bulletin - Week 43 : 21/10/2013-27/10/2013, 01 November 2013, Issue No. 502: Low Flu Activity so far

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  • EuroFlu - Weekly Electronic Bulletin - Week 43 : 21/10/2013-27/10/2013, 01 November 2013, Issue No. 502: Low Flu Activity so far

    [Source: EuroFlu, full page: (LINK). Extracts.]


    EuroFlu - Weekly Electronic Bulletin - Week 43 : 21/10/2013-27/10/2013, 01 November 2013, Issue No. 502

    Influenza activity still low in Europe


    Summary, week 43/2013
    • Low levels of influenza activity in the WHO European Region continue, with only a few countries reporting sporadic influenza detections among samples from sentinel and non-sentinel sources.
    • The number of hospitalizations due to severe acute respiratory infection (SARI) remained at a preseason level.
    • None of the SARI cases tested so far was found positive for influenza.

    The EuroFlu bulletin describes and comments on influenza activity in the 53 Member States in the WHO European Region to provide information to public health specialists, clinicians and the public on the timing of the influenza season, the spread of influenza, the prevalence and characteristics of circulating viruses (type, subtype and lineage) and severity.

    For a description of influenza surveillance in the WHO European Region see below.


    Virological surveillance for influenza

    During week 43/2013, a total of 5004 specimens was tested for influenza, 58 (1.2%) of which were positive: 44 (76%) were positive for influenza A and 14 (24%) for influenza B (Fig. 1 and 2).
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    Of the 26 influenza A viruses that were subtyped during week 43/2013; 12 were A(H1N1)pdm09 and 14 A(H3N2) (Fig. 2a).

    Since the beginning of the season (week 40/2012), 137 influenza viruses from sentinel and non-sentinel sources have been detected and typed.
    Cumulatively, 42 (31%) viruses were influenza B and 95 (69%)influenza A.

    Of the 62 influenza A viruses that have been subtyped, 25 (40%) were A(H1N1)pdm09 and 37 (60%) were A(H3N2) (Fig. 2b).
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    Since very few influenza viruses were detected during week 43/2013, 37 countries reported ?none? in the dominant virus type category (Map 1).


    Virus strain characterizations

    Circulating influenza viruses are assessed each season for their antigenic and genetic characteristics, to determine the extent of their antigenic similarity to the viruses included in the seasonal influenza vaccine, and determine the prevalence of mutations that affect pathogenicity or are associated with susceptibility to antiviral drugs.

    Since week 40/2013, 3 countries (Denmark, Finland and Norway) have characterized 6 influenza viruses genetically: 4 A(H3N2), 1 A(H1N1)pdm09 and 1 influenza B virus (Yamagata lineage).
    • 4 A(H3N2) viruses belonged to the subgroup (3C) represented by A/Texas/50/2012 in the A/Perth/16/2009, A(H3) clade;
    • 1 A(H1N1)pdm09 belonged to the group (6) represented by A/St Petersburg/27/2011 in the A(H1N1)pdm09 clade;
    • 1 influenza B virus belonged to the clade 2 represented by B/Massachusetts/02/2012 in the B(Yamagata) lineage.

    No viruses have been screened for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir this season.

    For the 2013/2014 northern hemisphere influenza season, WHO recommended inclusion of A/California/7/2009 (H1N1)pdm09-like, A(H3N2) virus antigenically like the cell-propagated prototype virus A/Victoria/361/2011 and B/Massachusetts/2/2012-like viruses in vaccines (see the WHO headquarters web site).


    Outpatient surveillance for influenza-like illness (ILI) and/or acute respiratory infection (ARI)

    Similarly to previous weeks, all reporting countries in the Region reported low influenza activity (Map 2) during week 43/2013, with most reporting a stable trend (Map 4) with mainly no or sporadic influenza activity (Map 3), which is usual for this time of year

    ILI and ARI consultation rates were below the national baselines or at preseason levels in all countries reporting clinical data during week 43/2013.

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    The number of ILI and ARI cases testing positive for influenza in the Region remained low, with only 15 of the sentinel samples testing positive for influenza during week 43 (Fig. 5). Fig. 5 presents historical positivity rates (%); the number of specimens in weeks 40?43 2013 was not sufficient for calculation of positivity, which requires at least 20 influenza positive specimens per week.
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    15 (2.4%) of the 637 specimens collected from sentinel sources tested positive during week 43/2013, with more than half being influenza B Click here for a detailed overview in a table format.
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    Hospital surveillance for SARI

    In week 43/2013 the number of SARI hospitalizations remained at interseason levels in reporting countries participating in hospital surveillance for SARI in the WHO European Region (Fig. 7).
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    None of the 114 SARI samples collected in Belarus, Georgia, Kazakhstan, Kyrgyzstan, Republic of Moldova, Russian Federation and Ukraine tested positive for influenza during week 43/2013. Click here for a detailed overview in table format.

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    Since week 40/2013, Ireland and the United Kingdom reported 8 hospitalized laboratory-confirmed influenza cases, with 4 of them being influenza B, 2 A(H1N1)pdm09 and 2 A unsubtyped. For more information on surveillance of confirmed hospitalized influenza, please see ECDC?s Weekly Influenza Surveillance Overview (WISO) at European Centre for Disease Prevention and Control web site.


    EuroMOMO (European Mortality Monitoring Project)

    EuroMOMO is a project set up to develop and operate a routine public health mortality monitoring system to detect and measure, on a real-time basis, excess deaths related to influenza and other possible public health threats across 20 European Union (EU) countries.

    Pooled analysis of week data for 43/2013 showed that all-cause mortality was within the normal range for all reporting countries. Results of pooled analysis may vary, depending on which countries are included in the weekly analysis. For more information about the EUROMOMO mortality monitoring system please click here).

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    Country comments (where available)
    • Republic of Moldova
      • This week 19 samples (17 were sentinel) were tested for Influenza A and B - none of them were positive.
      • 2 specimens were positive for RNA Human Parainfluenza virus type 1 and 3, respectively, and 3 - positive for RNA Rhinovirus; in 1 sample were detected RNA Human Parainfluenza virus and RNA hRSV.

    (?)


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