[Source: EuroFlu, full page: (LINK). Extract.]
EuroFlu - Weekly Electronic Bulletin - Week 1 : 30/12/2013-05/01/2014 - 10 January 2014, Issue No. 512
Influenza activity increasing in western Europe and Turkey
Summary, week 1/2014
- The reporting of influenza surveillance data for week 1/2014 is incomplete due to the holidays, and the data should be interpreted with caution.
- While the consultation rates for influenza-like illness (ILI) and acute respiratory infection (ARI) in outpatient clinics increased in Spain, Portugal and Turkey, low levels were generally reported throughout the WHO European Region.
- The numbers of influenza A(H3N2), A(H1N1)pdm09 and influenza B detections have increased, with the majority being influenza A.
- The number of reported hospitalizations due to severe acute respiratory infection (SARI) remained low, but 2 cases associated with influenza A infection were reported for week 1/2014.
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 1/2014 the number of influenza detections in the WHO European Region increased from those in previous weeks.
In total, 5899 specimens from sentinel and non-sentinel sources were tested for influenza during week 1/2014, 615 (10.4%) of which were positive: 574 (93%) influenza A and 41 (7%) influenza B (Fig. 1 and 2). Detections are probably low due to underreporting by several countries during the holidays.
Of the 352 influenza A viruses that were subtyped during week 1/2014, 165 (47%) were A(H1N1)pdm09 and 187 (53%) A(H3N2) (Fig. 2a).
Since the beginning of weekly monitoring (week 40/2013), sentinel and non-sentinel sources have yielded 2580 influenza detections: 2290 (89%) were influenza A viruses and 290 (11%) influenza B (Fig. 2b).
Of the 1546 influenza A viruses that have been subtyped, 724 (47%) were A(H1N1)pdm09 and 822 (53%) were A(H3N2) (Fig. 2b).
9 countries (Bulgaria, France, Italy, Norway, Portugal, Spain, Sweden, Turkey and the United Kingdom) reported influenza A to be the dominant virus, as shown in Map 1 and the tabulated country-specific data.
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, 6 countries (Denmark, Germany, Latvia, Portugal, the Russian Federation and the United Kingdom (England)) have characterized 26 influenza viruses antigenically:
- 16 were A(H1N1)pdm09 viruses (A/California/7/2009 (H1N1)-like);
- 6 were A(H3N2) viruses (A/Texas/50/2012 (H3N2)-like);
- 2 B/Yamagata/16/88 lineage viruses (1 B/Massachusetts/2/2012-like and 1 B/Wisconsin/1/2010-like) and
- 2 B/Victoria/2/87 lineage viruses (B/Brisbane/60/2008-like).
10 countries (Belgium, Denmark, Finland, Germany, the Netherlands, Norway, Portugal, Spain, Sweden and the United Kingdom (Scotland)) have characterized 70 influenza viruses genetically: 28 A(H3N2), 33 A(H1N1)pdm09, and 9 influenza B viruses.
- The 28 A(H3N2) viruses belonged to genetic subgroup 3C, represented by A/Texas/50/2012 in the A/Perth/16/2009 clade;
- the 33 A(H1N1)pdm09 viruses belonged to genetic group 6, represented by A/St Petersburg/27/2011;
- 1 influenza virus belonged to clade 1A of the B/Victoria lineage, represented by B/Brisbane/60/2008;
- of 8 B/Yamagata lineage viruses, 5 belonged to clade 2, represented by B/Massachusetts/02/2012 and 3 to clade 3, represented by B/Wisconsin/1/2010.
Since week 40/2013, 6 countries (the Netherlands, Norway, Portugal, Spain, Sweden and the United Kingdom (England)) have screened 44 influenza A(H1N1)pdm09, 27 influenza A(H3N2) and 6 influenza B viruses for susceptibility to oseltamivir and zanamivir.
All showed susceptibility to both drugs.
The 24 influenza A(H1N1)pdm09 and 18 influenza A(H3N2) viruses screened for susceptibility to adamantanes were found to be resistant.
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)
During week 1/2014, 2 countries (Spain and Turkey) reported medium intensity of influenza (Map 2). Portugal reported widespread activity; Turkey reported regional activity, and several countries in western Europe reported local influenza activity (Map 3) with associated increasing trends (Map 4).
During week 1/2014, consultation rates for ILI and/or ARI remained below the national baselines, and the rate appeared to be decreasing in some countries, but this might be due to decreased reporting during the holiday period.
The number of ILI and ARI cases testing positive for influenza in the Region has slowly increased since week 48/2013 (Fig. 5). During week 1/2014, 545 sentinel specimens tested positive for influenza; they were derived mainly from specimens collected in western European countries.
During week 1/2014, 158 (29%) of the 545 specimens collected from sentinel sources tested positive for influenza, the majority being influenza A(H3) (Fig. 6a). Click here for a detailed overview in a table format.
Hospital surveillance for SARI
The number of SARI hospitalizations has slowly increased since week 40/2013, but it remains at low levels in reporting countries participating in hospital surveillance for SARI in the WHO European Region (Fig. 7).
During week 1/2014, 2 of the 28 SARI samples collected in Kazakhstan, the Republic of Moldova and Serbia tested positive for influenza A (1 H3N2 and 1 H1N1pdm09) (Fig. 8a), which is in line with the results of outpatient surveillance. Click here for a detailed overview in table format.
Since week 40/2013, Ireland, France, Spain, Sweden and the United Kingdom have reported 173 hospitalized laboratory-confirmed influenza cases in total: 13 influenza B, 75 A(H1N1)pdm09, 15 A(H3) and 70 type A not subtyped. 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 presented by countries reporting on RSV, the positivity rate has been gradually increasing since week 40/2013 and picked up in week 50/2013 giving a slightly later start compared to 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. For week 1, all-cause mortality has been within the normal range for all reporting countries.
For the latest news on EUROMOMO please click here.
Country comments (where available)
- Republic of Moldova: 1 sample was tested for Influenza A and B - none of them were positive.
- Scotland: Please note that the GP consultation rates for ILI and ARI were adjusted to account for the reduced number of working days in week 01. The data for this week must be interpreted with caution.
- Sweden: The epidemic in Sweden is thus far concentrated in Northern Sweden.