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EuroFlu - Weekly Electronic Bulletin - Week 43 : 22/10/2012-28/10/2012 - 02 November 2012, Issue N? 460 (edited): Since week 40, 55% of typed A virus were H1pdm09

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  • EuroFlu - Weekly Electronic Bulletin - Week 43 : 22/10/2012-28/10/2012 - 02 November 2012, Issue N? 460 (edited): Since week 40, 55% of typed A virus were H1pdm09

    [Source: EuroFlu, full page: (LINK). Edited.]
    EuroFlu - Weekly Electronic Bulletin - Week 43 : 22/10/2012-28/10/2012 - 02 November 2012, Issue N? 460

    Continuing low levels of influenza activity in Europe



    Summary, week 43/2012

    Influenza activity is at low levels in all countries in the WHO European Region, with only few reporting sporadic influenza detections. All of the 18 countries that have established epidemic thresholds reported consultation rates for influenza-like illness (ILI) and/or acute respiratory infection (ARI) that were below their thresholds.

    The number of severe acute respiratory infection (SARI) cases detected through hospital surveillance was similar to that in the previous week, and none of the specimens tested was positive for influenza.

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



    Virological surveillance for influenza

    Overall, a total of 27 specimens tested positive for influenza in week 43/2012: 17 were influenza A and 10 were influenza B.

    Of the influenza A viruses, 10 were subtyped: 4 as A(H3) and 6 as A(H1)pdm09 (Fig. 1).

    Since week 40/2012, 128 specimens of influenza viruses from sentinel and non-sentinel sources have been typed and subtyped: 89 (70%) were influenza A and 39 (30%) were influenza B.

    Of the influenza A viruses 51 were subtyped: 23 (45%) as A(H3) and 28 (55%) as A(H1)pdm09.



    The map below presents the weekly reported dominant virus type. No country reported a dominant virus type in week 43/2012.


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    Outpatient surveillance for ILI/ARI

    ILI and ARI consultation rates are at usual levels for this time of year.

    Of the 38 countries reporting on influenza intensity and geographic spread, all reported low levels of intensity; 30 reported no activity and 8 reported sporadic activity. 32 countries reported stable trends; 2 reported a decrease and 4 reported increases in influenza activity.
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    The proportion of ILI and ARI cases from sentinel surveillance testing positive for influenza in the Region is low; of the 465 specimens tested, only 1 (0.2%) was positive.

    See Fig. 2 for historical percentage positivity rates. The numbers of specimens in weeks 40?43/2012 have not been sufficient to warrant presentation; at least 20 specimens per week need to test positive for influenza.


    Of 465 specimens, 1 (0.2%) tested positive for influenza A(H3). Click here for a detailed overview of cumulative influenza virus detections by type and subtype since week 40/2012.

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    26 specimens were reported positive for influenza: 16 were influenza A and 10 were influenza B. Of the influenza A viruses, 9 were subtyped: 3 as A(H3) and 6 as A(H1)pdm09.



    Hospital surveillance for SARI

    Of 11 countries with SARI surveillance, 8 (Armenia, Belarus, Georgia, Kazakhstan, Republic of Moldova, Russian Federation, Serbia and Ukraine) reported hospitalizations due to SARI, with most cases occurring in the youngest age group (Fig. 3).



    Of the 85 specimens collected from hospitalized SARI cases, none tested positive for influenza. The specimens were collected in 7 countries (Armenia, Belarus, Georgia, Kazakhstan, Kyrgyzstan, Russian Federation and Ukraine). Click here for a detailed overview of cumulative influenza virus detections by type and subtype since week 40/2012.

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    Monitoring of susceptibility to antiviral drugs

    Since week 40/2012, 1 country (Sweden) has screened 3 influenza A(H3N2) viruses for susceptibility to oseltamivir and zanamivir, and to adamantanes. All showed susceptibility to oseltamivir and zanamivir, but resistance to adamantanes.


    Virus characterizations

    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 40/2012, 1 country (Sweden) has characterized 2 influenza viruses genetically: 1 belonged to the subgroup represented by A/Perth/10/2010 in the A/Victoria/208/2009, A(H3) group 5; 1 belonged to the subgroup represented by A/Victoria/361/2011 in the A/Victoria/208/2009, A(H3) group 3C.

    In the 2012/2013 northern hemisphere influenza season, WHO recommends inclusion of A/California/7/2009 (H1N1)pdm09-like, A/Victoria/361/2011 (H3N2)-like and B/Wisconsin/1/2010-like (from the B/Yamagata lineage) viruses in trivalent vaccines.



    Description of influenza surveillance

    The EuroFlu bulletin describes and comments on influenza activity in the 53 countries in the WHO European Region. Influenza activity is monitored through surveillance of ILI, ARI and/or hospital-based surveillance for severe disease. Primary care clinics conduct surveillance for ILI and/or ARI in most countries in the Region, although some countries routinely perform hospital-based surveillance. Surveillance data in the Region are collected from sentinel and non-sentinel systems.

    Sentinel data come from a network of designated clinicians who routinely and systematically collect respiratory specimens from ILI, ARI or SARI cases according to standard case definitions. Non-sentinel data come from a variety of other sources, including community outbreaks, general practitioners and hospitals that are not part of the sentinel surveillance system for influenza and may not use a standard case definition for ILI, ARI or SARI.

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    Country comments (where available)

    Republic of Moldova: In the 43rd week 10 sentinel samples were tested: 3 specimens were positive for both DNA Adenovirus and Parainfluenza virus type 3; 1 sample was positive for both DNA Adenovirus and Parainfluenza virus type 2; and 1 sample was positive for DNA Adenovirus. Influenza viruses were not detected in any of the tested specimens.

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