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EuroFlu - Weekly Electronic Bulletin - Week 10 : 03/04/2014-09/03/2014 - 14 March 2014, Issue No. 521 (edited)

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  • EuroFlu - Weekly Electronic Bulletin - Week 10 : 03/04/2014-09/03/2014 - 14 March 2014, Issue No. 521 (edited)

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


    EuroFlu - Weekly Electronic Bulletin - Week 10 : 03/04/2014-09/03/2014 - 14 March 2014, Issue No. 521

    Stable or decreasing Influenza activity in most countries of the WHO European Region


    Summary, week 10/2014
    • Consultation rates for influenza-like illness (ILI) and acute respiratory infection (ARI) continue to decrease throughout most parts of the WHO European Region with the majority of countries reporting low intensity during week 10/2014.
    • For the last four consecutive weeks, the percentage of positive sentinel ILI/ARI specimens has been decreasing indicating that the influenza season in the European Region has passed its peak.
    • Based on the results of outpatient and hospital surveillance, influenza A(H1N1)pdm09 and A(H3N2) viruses continue to co-circulate in the Region, with A(H1N1)pdm09 remaining predominant in most northern European countries while A(H3N2) predominated in eastern European countries and in Germany, Ireland and Italy.
    • In contrast to the previous season, very few influenza B detections have been reported 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

    During week 10/2014, the total number of specimens tested for influenza as well as the positivity rate decreased in comparison with previous weeks: 13 443 specimens from sentinel and non-sentinel sources were tested for influenza, 2693 (20%) of which were positive – 2555 (95%) influenza A and 138 (5%) influenza B (Fig. 1 and 2).
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    Influenza A has remained the dominant virus type across the Region since week 40/2013. Of the 1579 influenza A viruses that were subtyped during week 10/2014, 843 (53%) were A(H1N1)pdm09 and 736 (47%) A(H3N2) (Fig. 2a).

    Since the beginning of weekly monitoring (week 40/2013), sentinel and non-sentinel sources have yielded 30 968 influenza detections: 29 675 (96%) were influenza A and 1293 (4%) influenza B viruses (Fig. 2b). Of the 21 087 influenza A viruses that have been subtyped, 12 836 (61%) were A(H1N1)pdm09 and 8251 (39%) were A(H3N2).

    In addition, since week 40/2013, the lineage of 129 influenza B viruses has been determined: 118 (91%) belonged to the B/Yamagata lineage (the lineage of the B virus recommended by WHO for inclusion in trivalent seasonal influenza vaccines) and 11 (9%) to the B/Victoria lineage.
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    Similar to the previous week, 29 countries reported influenza A as the dominant type in week 10/2014. Turkey was the only country reporting influenza B as dominant, but the number of detections was low (Map 1 and country table).

    Of the 26 countries providing data on dominant subtypes, influenza A(H3N2) was reported as dominant in eight countries (Georgia, Germany, Ireland, Italy, the Republic of Moldova, Romania, Slovenia and Ukraine), while nine countries (Denmark, Hungary, Iceland, Kazakhstan, Norway, Spain, Sweden, the former Yugoslav Republic of Macedonia and the United Kingdom (Scotland and Wales)) reported A(H1N1)pdm09 as dominant.

    Nine countries (Albania, Belgium, Bulgaria, France, Greece, Latvia, Luxembourg, the Netherlands and the Russian Federation) reported A(H1N1)pdm09 and A(H3N2) as co-dominant.


    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.

    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 and B/Massachusetts/2/2012-like (Yamagata lineage) viruses in vaccines (see the WHO headquarters web site).

    The WHO Consultation on the Composition of Influenza Virus Vaccines for the Northern Hemisphere 2014–2015 took place in week 7/2014, and the WHO expert group recommended no change from the vaccine composition for the 2013–2014 season. (see the WHO headquarters web site).

    Since week 40/2013, 1005 influenza viruses characterized antigenically by 13 countries (the Czech Republic, Denmark, Finland, Germany, Latvia, the Netherlands, Norway, Portugal, Romania, the Russian Federation, Slovakia, Switzerland and the United Kingdom (England, Scotland)) corresponded with the viruses recommended by WHO for inclusion in the current northern hemisphere seasonal influenza vaccine (Fig. 3).

    15 countries (Belgium, the Czech Republic, Denmark, Finland, Germany, Greece, Ireland, the Netherlands, Norway, Portugal, the Russian Federation, Spain, Sweden, Switzerland and the United Kingdom (Scotland)) have characterized 659 influenza viruses genetically (Fig. 4).
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    # Included in the WHO-recommended composition of influenza virus vaccines for use in the 2013/2014 northern hemisphere influenza season.

    * Included in the WHO-recommended composition of influenza virus vaccines for use in the 2014 southern hemisphere influenza season.


    Monitoring of susceptibility to antiviral drugs

    Since week 40/2013, eight countries (Greece, the Netherlands, Norway, Portugal, Spain, Sweden, the Russian Federation and the United Kingdom (England)) have screened 800 viruses for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir.

    Of the 629 A(H1N1)pdm09 viruses tested, 621 showed susceptibility to both drugs. Eight viruses carrying the neuraminidase H275Y amino acid substitution, causing resistance to oseltamivir, were detected in the United Kingdom in hospitalized patients, most of whom were treated with neuraminidase inhibitors.

    Of the 136 influenza A(H3N2) viruses tested, 135 showed susceptibility to both drugs. The remaining virus, detected in the United Kingdom in a hospitalized immunocompromised patient treated with oseltamivir, carried the neuraminidase E119V amino acid substitution, and showed reduced inhibition by oseltamivir but normal inhibition by zanamivir.

    All 35 influenza B viruses tested showed susceptibility to both oseltamivir and zanamivir.

    So far, there is no indication of increased resistance to the neuraminidase inhibitors during the winter of 2013–2014. All 102 influenza A(H1N1)pdm09 and 75 influenza A(H3N2) viruses screened for susceptibility to adamantanes were found to be resistant.


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

    During week 10/2014, most European countries continued to report low-intensity influenza activity (Map 2), with only a few countries reporting increasing trends (Map 4). Regarding geographic spread, influenza activity was predominantly regional or sporadic in most countries (Map 3).

    During week 10/2014, ILI/ARI consultation rates either stabilized or decreased in most countries in the Region. Of the 22 countries with established national thresholds, consultation rates still remained above or at threshold levels in most. In a number of northern and western countries (the Czech Republic, Denmark, Germany, Latvia, Lithuania, Luxembourg, the Netherlands, Norway, Slovakia, Switzerland and the United Kingdom (England)) consultation rates have been very low since the beginning of the season (mostly below threshold) and much lower than last season.

    For the last four consecutive weeks, the percentage of influenza-positive sentinel ILI/ARI specimens has been decreasing, indicating that the influenza season has passed its peak and is potentially coming to an end in Bulgaria and Spain, where the influenza season started earlier than elsewhere in the Region.

    (…)

    The percentage of positive sentinel ILI/ARI specimens remained lower than in the same week of the four preceding seasons (Fig. 5).
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    During week 10/2014, 429 (29%) of the 1475 specimens collected from sentinel sources tested positive for influenza, the majority being influenza A(H3N2) similar to previous weeks (Fig. 6a). The number of influenza B detections has remained low since the beginning of the season in contrast to the same period last year, when more than half of sentinel influenza detections were influenza B. Click here for a detailed overview in a table format.
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    Hospital surveillance for SARI

    Among countries performing surveillance of severe disease due to influenza, the number of SARI hospitalizations as well as the positivity rate decreased slightly in comparison with the previous weeks (Fig. 7). Most SARI cases were reported in those aged 0–4 years.

    Albania, Belarus, Georgia, Romania and Serbia reported increases in SARI cases in the age groups 15–64 years as well as ≥65 years. Only in Serbia did this coincide with an increase in the influenza positivity rate.
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    During week 10/2014, 70 (26%) of the 266 SARI samples collected in Albania, Armenia, Belarus, Georgia, Kazakhstan, the Republic of Moldova, Romania, the Russian Federation, Serbia, Slovakia and Ukraine tested positive for influenza A, the majority being A(H3N2), similar to the situation in outpatient surveillance (Fig. 8a). Click here for a detailed overview in table format.
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    For week 10/2014, 6 countries (France, Ireland, Romania, Spain, Sweden and the United Kingdom) reported 206 hospitalized, laboratory-confirmed influenza cases ; 204 cases tested positive for influenza A virus and 2 for influenza B virus.

    Since week 40/2013, 7 countries have reported 3707 hospitalized, laboratory-confirmed influenza cases: 3684 (99%) were related to influenza virus type A infection and 23 (1%) to type B virus infection. Of 2496 subtyped influenza A viruses, 1887 (76%) were A(H1N1)pdm09 and 609 (24%) were A(H3N2).

    5 countries reported a total of 306 fatal cases, and 303 (99%) cases were associated with influenza virus type A infection and 3 (1%) with type B virus. Of 237 influenza A viruses subtyped for fatal cases, 194 (82%) were A(H1N1)pdm09 and 43 (18%) were A(H3N2).

    SARI and hospitalized laboratory-confirmed influenza cases reported to the European Centre for Disease Prevention and Control (ECDC) differ in that the former include a higher proportion of influenza A(H3N2) and a lower proportion of influenza A(H1N1)pdm09 than the latter. These findings are similar to the results of outpatient surveillance in individual countries.

    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.


    Respiratory syncytial virus (RSV)

    Based on the data reported by countries on RSV, detections peaked in week 50/2013 and have decreased in all the reporting countries since. This represents a slightly later start than in the previous season (see Country data and graphs for individual country data).


    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 10/2014 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.

    (…)

    Country comments (where available)
    • Republic of Moldova:
      • In week 10 were tested 28 samples for influenza viruses: 13 were positive for RNA A(H3N2); 1 sample - RNA hRSV;

    • Romania:
      • We report in TESSy only data from sentinel SARI Surveillance, but we also monitor the confirmed SARI cases detected by routine surveillance.
      • Including Week 10, we have a total number of 44 confirmed SARI cases, 22 with A(H1)pdm09, 21 with A(H3) and 1 with coinfection A(H1)pdm09&A(H3).
      • The total number of death is 11, all confirmed with influenza virus A(H1)pdm09.
      • Nine out of 11 cases who died are females, the median age is 53 years and the average is 49.
      • Nine out of 11 cases who died had underlying risk conditions, but none of them had been previously vaccinated against influenza.
      • In the same period of the previous season, the same number of death (11) confirmed with influenza had been registered, but 9 with influenza A(H1)pdm09 and 2 with influenza B.

    (…)


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