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EuroFlu - Weekly Electronic Bulletin - Week 46 : 12/11/2012-18/11/2012 - 23 November 2012, Issue N? 463: H1pdm09, H3 & B Co-Circulation
[Source: EuroFlu, full page: (LINK). Edited.]
EuroFlu - Weekly Electronic Bulletin - Week 46 : 12/11/2012-18/11/2012 - 23 November 2012, Issue N? 463
Summary, week 46/2012
Description of influenza surveillance
The EuroFlu bulletin describes and comments on influenza activity in the 53 countries in the WHO European Region. Most of these countries monitor influenza activity through surveillance of influenza-like illness (ILI) and/or acute respiratory infection (ARI) in primary care clinics, with some countries also conducting hospital-based surveillance for severe disease.
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, which may not use a standard case definition for ILI, ARI or SARI.
This report collates and interprets the epidemiological and virological data provided from the different surveillance systems in the Region, to provide information to clinicians, public health specialists and the public on the timing of the influenza season, the spread of influenza in the Region, the prevalence and characteristics of circulating influenza viruses (type, subtype/lineage, antigenic and genetic properties), and severity in terms of numbers of confirmed cases, geographic spread, disease caused and impact on health systems.
Virological surveillance for influenza
This section describes which influenza viruses are circulating according to influenza type (A and B) and subtype (A(H3N2) and A(H1N1)pdm09) or lineage (B/Victoria or B/Yamagata).
Overall, a total of 108 specimens tested positive for influenza in week 46/2012: 60 were type A and 48 were type B.
Of the influenza A viruses, 30 were subtyped: 16 as A(H3N2) and 14 as A(H1N1)pdm09 (Fig. 1).
Since week 40/2012, 440 influenza viruses from sentinel and non-sentinel sources have been typed: 278 (63%) were influenza A and 162 (37%) influenza B.
Of the influenza A viruses 165 were subtyped: 90 (55%) as A(H3N2) and 75 (45%) as A(H1N1)pdm09.
Similar to previous weeks, owing to the low number of viruses detected in week 46/2012, no country reported a dominant virus, as shown in the map below.
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Virus strain characterizations
Influenza viruses are assessed each season for their antigenic and genetic characteristics, to determine the extent of their antigenic and genetic similarity to the viruses included in the seasonal influenza vaccine and the prevalence of mutations that affect pathogenicity or are associated with susceptibility to antiviral drugs.
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 (see more at WHO web site).
Since week 40/2012, 1 country (Germany) has characterized 7 influenza viruses antigenically (Fig. 3). 5 countries (Finland, Germany, Norway, Portugal, Sweden) have characterized 18 influenza viruses genetically (Fig. 4).
# Included in the WHO-recommended composition of influenza virus vaccines for use in the 2012/2013 northern hemisphere influenza season. * Included in the WHO-recommended composition of influenza virus vaccines for use in the 2013 southern hemisphere influenza season.
Monitoring of susceptibility to antiviral drugs
Since week 40/2012, 2 countries (the Netherlands and Sweden) have screened 4 viruses for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir.
All 3 A(H3N2) viruses and the single A(H1N1)pdm09 virus showed susceptibility to oseltamivir and zanamivir.
The 3 influenza A(H3N2) viruses were screened for susceptibility to adamantanes and found to be resistant.
Outpatient surveillance for influenza-like illness (ILI) and/or acute respiratory infection (ARI)
Consultation rates for ILI and ARI remain at low levels throughout the WHO European Region. 29 out of 42 countries reported no influenza activity, and only 8 of 41 reported increasing trends.
The Republic of Moldova is still the only country, among 18 with established epidemic thresholds, that reported ILI/ARI consultation rates above its national threshold. The map below presents the weekly intensity, geographic spread and trend for Europe.
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The influenza-positivity rate among ILI and ARI cases, as well as the number of specimens tested from sentinel sources, is relatively stable and similar to the previous week: 15 (2.4%) of 628 specimens tested were influenza positive. The number of specimens testing positive for influenza in weeks 40?46/2012 remains below the set cut-off for presentation, which requires at least 20 positive specimens per week (see Fig. 2).
Of 628 specimens from sentinel sources, 8 tested positive for influenza A and 7 for influenza B.
Click here for a detailed overview of cumulative influenza virus detections by type and subtype since week 40/2012.
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93 specimens were reported positive for influenza: 52 were influenza A and 41 were influenza B. Of the influenza A viruses, 23 were subtyped: 10 as A(H3N2) and 13 as A(H1)pdm09.
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Hospital surveillance for SARI
This week, 10 countries (Armenia, Belarus, Georgia, Kazakhstan, Kyrgyzstan, Republic of Moldova, Romania, Russian Federation, Serbia and Ukraine) reported on hospitalizations due to SARI.
Sentinel SARI hospitalizations remain low and at pre-season levels, with a slight increase in the number of samples tested.
Most of the cases have occurred in the group aged 0?4 years (Fig. 3). 1 SARI case reported by Serbia was positive for influenza B, yielding an influenza-positivity rate of 0.8% this week.
In week 46, 127 specimens were collected from hospitalized SARI cases in 9 countries (Armenia, Belarus, Georgia, Kazakhstan, Kyrgyzstan, Romania, Russian Federation, Serbia 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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For the surveillance of confirmed hospitalized influenza see the Weekly Influenza Surveillance Overview (WISO) at European Centre for Disease Prevention and Control web site.
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Country comments (where available)
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EuroFlu - Weekly Electronic Bulletin - Week 46 : 12/11/2012-18/11/2012 - 23 November 2012, Issue N? 463
Summary, week 46/2012
- Levels of influenza activity in the Region remain low, with co-circulation of influenza A(H1N1)pdm09, A(H3N2) and type B viruses reported by countries this week.
- The number of specimens testing positive for influenza is typical for this time of the year and comparable with previous seasons.
- The number of hospitalizations due to severe acute respiratory infection (SARI) was similar to that in the previous week, with only 1 case testing positive for influenza B.
Description of influenza surveillance
The EuroFlu bulletin describes and comments on influenza activity in the 53 countries in the WHO European Region. Most of these countries monitor influenza activity through surveillance of influenza-like illness (ILI) and/or acute respiratory infection (ARI) in primary care clinics, with some countries also conducting hospital-based surveillance for severe disease.
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, which may not use a standard case definition for ILI, ARI or SARI.
This report collates and interprets the epidemiological and virological data provided from the different surveillance systems in the Region, to provide information to clinicians, public health specialists and the public on the timing of the influenza season, the spread of influenza in the Region, the prevalence and characteristics of circulating influenza viruses (type, subtype/lineage, antigenic and genetic properties), and severity in terms of numbers of confirmed cases, geographic spread, disease caused and impact on health systems.
Virological surveillance for influenza
This section describes which influenza viruses are circulating according to influenza type (A and B) and subtype (A(H3N2) and A(H1N1)pdm09) or lineage (B/Victoria or B/Yamagata).
Overall, a total of 108 specimens tested positive for influenza in week 46/2012: 60 were type A and 48 were type B.
Of the influenza A viruses, 30 were subtyped: 16 as A(H3N2) and 14 as A(H1N1)pdm09 (Fig. 1).
Since week 40/2012, 440 influenza viruses from sentinel and non-sentinel sources have been typed: 278 (63%) were influenza A and 162 (37%) influenza B.
Of the influenza A viruses 165 were subtyped: 90 (55%) as A(H3N2) and 75 (45%) as A(H1N1)pdm09.
(?)
Virus strain characterizations
Influenza viruses are assessed each season for their antigenic and genetic characteristics, to determine the extent of their antigenic and genetic similarity to the viruses included in the seasonal influenza vaccine and the prevalence of mutations that affect pathogenicity or are associated with susceptibility to antiviral drugs.
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 (see more at WHO web site).
Since week 40/2012, 1 country (Germany) has characterized 7 influenza viruses antigenically (Fig. 3). 5 countries (Finland, Germany, Norway, Portugal, Sweden) have characterized 18 influenza viruses genetically (Fig. 4).
Monitoring of susceptibility to antiviral drugs
Since week 40/2012, 2 countries (the Netherlands and Sweden) have screened 4 viruses for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir.
All 3 A(H3N2) viruses and the single A(H1N1)pdm09 virus showed susceptibility to oseltamivir and zanamivir.
The 3 influenza A(H3N2) viruses were screened for susceptibility to adamantanes and found to be resistant.
Outpatient surveillance for influenza-like illness (ILI) and/or acute respiratory infection (ARI)
Consultation rates for ILI and ARI remain at low levels throughout the WHO European Region. 29 out of 42 countries reported no influenza activity, and only 8 of 41 reported increasing trends.
The Republic of Moldova is still the only country, among 18 with established epidemic thresholds, that reported ILI/ARI consultation rates above its national threshold. The map below presents the weekly intensity, geographic spread and trend for Europe.
(?)
The influenza-positivity rate among ILI and ARI cases, as well as the number of specimens tested from sentinel sources, is relatively stable and similar to the previous week: 15 (2.4%) of 628 specimens tested were influenza positive. The number of specimens testing positive for influenza in weeks 40?46/2012 remains below the set cut-off for presentation, which requires at least 20 positive specimens per week (see Fig. 2).
Click here for a detailed overview of cumulative influenza virus detections by type and subtype since week 40/2012.
(?)
93 specimens were reported positive for influenza: 52 were influenza A and 41 were influenza B. Of the influenza A viruses, 23 were subtyped: 10 as A(H3N2) and 13 as A(H1)pdm09.
(?)
Hospital surveillance for SARI
This week, 10 countries (Armenia, Belarus, Georgia, Kazakhstan, Kyrgyzstan, Republic of Moldova, Romania, Russian Federation, Serbia and Ukraine) reported on hospitalizations due to SARI.
Sentinel SARI hospitalizations remain low and at pre-season levels, with a slight increase in the number of samples tested.
Most of the cases have occurred in the group aged 0?4 years (Fig. 3). 1 SARI case reported by Serbia was positive for influenza B, yielding an influenza-positivity rate of 0.8% this week.
(?)
For the surveillance of confirmed hospitalized influenza see the Weekly Influenza Surveillance Overview (WISO) at European Centre for Disease Prevention and Control web site.
(?)
Country comments (where available)
- Norway: Moderate and increasing number of influenza virus detections. A(H1)pdm09, A(H3) and B Yamagata lineage viruses appear to be circulating sporadically, in approximately equal numbers. However, influenza B (Yamagata lineage) seems to be emerging as the most numerous although not yet fulfilling the criteria for predominance.
- Republic of Moldova: In the 46th week from 15 sentinel specimens, 2 samples were positive for RNA RSV and 4 sample - positive for DNA Adenovirus.
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