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EuroFlu - Weekly Bulletin, Wk 44 : 28/10-03/11/2013, 8 Nov '13, No. 503: Low activity

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  • EuroFlu - Weekly Bulletin, Wk 44 : 28/10-03/11/2013, 8 Nov '13, No. 503: Low activity

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

    EuroFlu - Weekly Electronic Bulletin, Week 44 : 28/10/2013-03/11/2013, 08 November 2013, Issue No. 503

    Influenza activity still low in Europe
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    Summary, week 44/2013
    • Similarly to previous seasons, influenza activity remained low in the WHO European Region during week 44/2013, with only a few countries reporting sporadic influenza detections among sentinel samples.
    • Since the start of the season, A(H1N1)pdm09, A(H3N2) and type B viruses have co-circulated.
    • The number of hospitalizations due to severe acute respiratory infection (SARI) is stable.
    • None of the SARI cases has tested positive for influenza so far this season.

    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

    Similarly to the previous week, a total of 5158 specimens was tested for influenza during week 44/2013, 72 (1.4%) of which were positive: 54 (75%) were positive for influenza A and 18 (25%) for influenza B (Fig. 1 and 2).
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    Of the 24 influenza A viruses that were subtyped during week 44/2013, 14 were A(H1N1)pdm09 and 10 A(H3N2) (Fig. 2a).

    Since the beginning of the season (week 40/2012), 216 influenza viruses from sentinel and non-sentinel sources have been detected and typed.

    Cumulatively, 62 (29%) viruses were influenza B and 154 (71%) influenza A. Of the 91 influenza A viruses that have been subtyped, 40 (44%) were A(H1N1)pdm09 and 51 (56%) were A(H3N2) (Fig. 2b).
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    Since very few influenza viruses were detected during week 44/2013, 38 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, 1 country (United Kingdom (England)) has characterized 2 influenza viruses antigenically: both were A(H1N1)pdm09 viruses (A/California/7/2009 (H1N1)-like).

    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).

    The 4 A(H3N2) viruses belonged to the subgroup 3C represented by A/Texas/50/2012 in the A/Perth/16/2009, A(H3) clade; the A(H1N1)pdm09 virus belonged to group 6 represented by A/St Petersburg/27/2011 in the A(H1N1)pdm09 clade; the influenza B virus belonged to clade 2 represented by B/Massachusetts/02/2012 in the B(Yamagata) lineage.

    Since week 40/2013, 1 country (Sweden) has screened 2 influenza A(H1N1)pdm09 viruses for susceptibility to oseltamivir and zanamivir, and to adamantanes. Both showed susceptibility to oseltamivir and zanamivir, but resistance to adamantanes.

    For the 2013/2014 northern hemisphere influenza season, WHO recommended inclusion of A/California/7/2009 (H1N1)pdm09-like, A/Texas/50/2012 (H3N2)-like (an egg-adapted virus antigenically like the cell-propagated prototype virus A/Victoria/361/2011) and B/Massachusetts/2/2012-like (Yamagata lineage) 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 44/2013, with most reporting a stable trend (Map 4) with mainly no or sporadic influenza activity (Map 3), which resembles the situation in previous seasons at this time of year.

    Consultation rates for ILI and/or ARI remained below the national baselines or at preseason levels in all countries reporting clinical data during week 44/2013.

    (?)

    The number of ILI and ARI cases testing positive for influenza in the Region remained low, with only 5 sentinel samples testing positive during week 44 (Fig. 5).

    Fig. 5 presents historical data on the weekly percentage of influenza positive sentinel ILI/ARI specimens from the previous 4 seasons; the percentage of sentinel ILI/ARI influenza positive samples was not calculated in weeks 40?44 2013, because there were fewer than 20 influenza positive specimens per week.
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    5 (0.8%) of the 629 specimens collected from sentinel sources tested positive during week 44/2013, with the majority being influenza A. Click here for a detailed overview in a table format.
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    Hospital surveillance for SARI

    The number of SARI hospitalizations in week 44/2013 was similar to those in previous weeks, and 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 88 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.

    (?)

    Since week 40/2013, Ireland and the United Kingdom reported 9 hospitalized laboratory-confirmed influenza cases, with 4 of them being influenza B, 2 A(H1N1)pdm09 and 3 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 44/2013 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 sentinel samples were tested for Influenza A and B - none of them were positive. 1 sample - positive for RNA hParainfluenza virus type 3, 1 sample - positive for RNA RSV, and 2 - positive for RNA Rhinovirus; in 1 sample were detected RNA Human Parainfluenza virus type 1 and RNA Rhinovirus.


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