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EuroFlu - Weekly Electronic Bulletin - Week 13 : 26/03/2012-01/04/2012 - 06 April 2012, Issue N? 440 (edited)
[Source: EuroFlu, full page: (LINK). Extracts, edited.]
Outpatient surveillance for ILI and ARI
39 countries reported on trends in clinical activity: 2 increasing, 8 stable, and 29 decreasing.
Of the 39 countries reporting on the geographical spread of influenza: 13 reported no or sporadic activity; 10, local activity; 7, regional activity; and 8, widespread activity.
No country reported high or very high intensity while low and medium intensity were reported by 25 and 14 countries respectively.
Of the 19 countries that reported a threshold for the 2011/2012 season, the consultation rates were above the threshold in 5 countries (Estonia, Latvia, the Russian Federation, Sweden and Switzerland). While influenza activity in Latvia passed its influenza peak two weeks ago, the clinical rates were near the threshold in Estonia, the Russian Federation, Sweden and Switzerland.
During week 13/2012 sentinel outpatient clinics collected 900 respiratory specimens, of which 319 (35%) tested positive for influenza viruses, a percentage that is lower than the previous week (41%).
Of these positive specimens, 229 (72%) were influenza type A and 90 (28%) were influenza B Table 1, Fig. 1).
In the 17 countries testing 20 or more sentinel specimens, influenza positivity ranged from 7% to 65%, with a median of 38% (mean: 36%).
Hospital surveillance for SARI
10 countries reported data for hospital-based sentinel surveillance of SARI: Armenia, Belarus, Georgia, Kazakhstan, Kyrgyzstan, the Republic of Moldova, Romania, the Russian Federation, Serbia and Ukraine.
125 respiratory specimens were collected from SARI patients, of which 36 (29%) were positive for influenza: 34 were type A and 2 were type B.
33 influenza A viruses were subtyped: 28 as A(H3) and 5 as A(H1)pdm09. (Fig. 2).
Further information on the sentinel SARI surveillance systems represented in the EuroFlu bulletin can be found in ?Overview of sentinel SARI systems in EuroFlu?.
Virological overview
During week 13/2012, 42 countries reported a dominant virus based on both sentinel and non-sentinel detections.
23 countries reported influenza A and/or A(H3N2) as the dominant virus and 4 reported co-dominance of influenza B with influenza A(H3N2). 15 countries reported that no virus was dominant.
Influenza virus type and subtype detections
Table 1 provides an overview of the influenza virus detections by type and subtype in sentinel ILI/ARI and SARI surveillance for both the current week and the period since week 40/2011.
Table 1. Influenza virus detections in sentinel specimens
[Specimens tested and viruses - Current week (number and %): ILI/ARI ? SARI - Cumulative since week 40 (number and %): ILI/ARI ? SARI]
During week 13/2012, 2201 specimens from non-sentinel sources were reported positive for influenza: 1859 (84%) type A and 342 (16%) type B.
Of the influenza A viruses, 885 were subtyped: 846 (96%) as A(H3N2) and 39 (4%) as A(H1N1)pdm09.
Since week 40/2011, 33 689 influenza viruses from sentinel and non-sentinel sources have been typed: 31 029 (92%) were influenza A and 2660 (8%) were influenza B.
Of the influenza A viruses, 4279 were subtyped: 3911 (91%) as A(H3N2) and 368 (9%) as A(H1N1)pdm09.
Virus strain characterizations
Influenza viruses are monitored each season for antigenic and genetic characteristics, to determine the extent to which they correspond with the viruses included in the seasonal influenza vaccine as well as the occurrence of mutations that affect pathogenicity or that are associated with susceptibility to antiviral drugs.
Since week 40/2011, 17 countries (Austria, the Czech Republic, Denmark, the United Kingdom (England), France, Germany, Greece, Hungary, Italy, Latvia, Portugal, Romania, the Russian Federation, Slovakia, Slovenia, Sweden, Switzerland) have characterized 1157 influenza viruses antigenically (Fig. 3).
17 countries (Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Latvia, Norway, Portugal, Romania, the Russian Federation, Spain, Sweden, Switzerland) have characterized 1020 influenza viruses genetically (Fig. 4).
# Included in the WHO-recommended composition of influenza virus vaccines for use in the 2011/2012 northern hemisphere influenza season.
* Included in the WHO-recommended composition of influenza virus vaccines for use in the 2012 southern hemisphere influenza season.
Further information
The EuroFlu bulletin describes and comments on influenza activity in the 53 countries in the WHO European Region. Further information can be obtained from the WHO/Europe, WHO headquarters and European Centre for Disease Prevention and Control web sites.
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EuroFlu - Weekly Electronic Bulletin - Week 13 : 26/03/2012-01/04/2012 - 06 April 2012, Issue N? 440
Influenza activity is decreasing in most countries of the WHO European Region
Current situation: week 13/2012
Influenza activity is decreasing in most countries of the WHO European Region
Current situation: week 13/2012
- This issue is based on data for week 13/2012 reported by 46 Member States in the WHO European Region.
- Consultation rates continue to decrease with only 5 countries reporting consultation rates above their thresholds, and percentages of influenza-positive cases decreased compared to the previous week.
- The number of hospitalizations due to severe acute respiratory infection (SARI) and the SARI influenza-positivity rate are slowly decreasing.
- Influenza A(H3N2) viruses continue to dominate, despite a slight increase in influenza B detections and a few A(H1N1)pdm09 detections.
Outpatient surveillance for ILI and ARI
39 countries reported on trends in clinical activity: 2 increasing, 8 stable, and 29 decreasing.
Of the 39 countries reporting on the geographical spread of influenza: 13 reported no or sporadic activity; 10, local activity; 7, regional activity; and 8, widespread activity.
No country reported high or very high intensity while low and medium intensity were reported by 25 and 14 countries respectively.
Of the 19 countries that reported a threshold for the 2011/2012 season, the consultation rates were above the threshold in 5 countries (Estonia, Latvia, the Russian Federation, Sweden and Switzerland). While influenza activity in Latvia passed its influenza peak two weeks ago, the clinical rates were near the threshold in Estonia, the Russian Federation, Sweden and Switzerland.
During week 13/2012 sentinel outpatient clinics collected 900 respiratory specimens, of which 319 (35%) tested positive for influenza viruses, a percentage that is lower than the previous week (41%).
Of these positive specimens, 229 (72%) were influenza type A and 90 (28%) were influenza B Table 1, Fig. 1).
In the 17 countries testing 20 or more sentinel specimens, influenza positivity ranged from 7% to 65%, with a median of 38% (mean: 36%).
Hospital surveillance for SARI
10 countries reported data for hospital-based sentinel surveillance of SARI: Armenia, Belarus, Georgia, Kazakhstan, Kyrgyzstan, the Republic of Moldova, Romania, the Russian Federation, Serbia and Ukraine.
125 respiratory specimens were collected from SARI patients, of which 36 (29%) were positive for influenza: 34 were type A and 2 were type B.
33 influenza A viruses were subtyped: 28 as A(H3) and 5 as A(H1)pdm09. (Fig. 2).
Further information on the sentinel SARI surveillance systems represented in the EuroFlu bulletin can be found in ?Overview of sentinel SARI systems in EuroFlu?.
Virological overview
During week 13/2012, 42 countries reported a dominant virus based on both sentinel and non-sentinel detections.
23 countries reported influenza A and/or A(H3N2) as the dominant virus and 4 reported co-dominance of influenza B with influenza A(H3N2). 15 countries reported that no virus was dominant.
Influenza virus type and subtype detections
Table 1 provides an overview of the influenza virus detections by type and subtype in sentinel ILI/ARI and SARI surveillance for both the current week and the period since week 40/2011.
Table 1. Influenza virus detections in sentinel specimens
[Specimens tested and viruses - Current week (number and %): ILI/ARI ? SARI - Cumulative since week 40 (number and %): ILI/ARI ? SARI]
- Specimens tested ? 900 - 125 - 32023 - 3679
- Influenza A + B ? 319 (35.4%) - 36 (28.8%) - 10004 (31.2%) - 549 (14.9%)
- Influenza A - 229 (71.8%) - 34 (94.4%) - 8935 (89.3%) - 525 (95.6%)
- Influenza B - 90 (28.2%) - 2 (5.6%) - 1069 (10.7%) - 24 (4.4%)
- Influenza A subtyped - 164 - 33 - 8069 - 494
- A (H1N1)pdm09 - 3 (1.8%) - 5 (15.2%) - 143 (1.8%) - 61 (12.4%)
- A (H3N2) - 161 (98.2%) - 28 (84.9%) - 7926 (98.2%) - 432 (87.5%)
- A (H1N1) - 0 (0.0%) - 0 (0.0%) - 0 (0.0%) - 1 (0.2%)
During week 13/2012, 2201 specimens from non-sentinel sources were reported positive for influenza: 1859 (84%) type A and 342 (16%) type B. Of the influenza A viruses, 885 were subtyped: 846 (96%) as A(H3N2) and 39 (4%) as A(H1N1)pdm09.
Since week 40/2011, 33 689 influenza viruses from sentinel and non-sentinel sources have been typed: 31 029 (92%) were influenza A and 2660 (8%) were influenza B.
Of the influenza A viruses, 4279 were subtyped: 3911 (91%) as A(H3N2) and 368 (9%) as A(H1N1)pdm09.
Virus strain characterizations
Influenza viruses are monitored each season for antigenic and genetic characteristics, to determine the extent to which they correspond with the viruses included in the seasonal influenza vaccine as well as the occurrence of mutations that affect pathogenicity or that are associated with susceptibility to antiviral drugs.
Since week 40/2011, 17 countries (Austria, the Czech Republic, Denmark, the United Kingdom (England), France, Germany, Greece, Hungary, Italy, Latvia, Portugal, Romania, the Russian Federation, Slovakia, Slovenia, Sweden, Switzerland) have characterized 1157 influenza viruses antigenically (Fig. 3).
17 countries (Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Latvia, Norway, Portugal, Romania, the Russian Federation, Spain, Sweden, Switzerland) have characterized 1020 influenza viruses genetically (Fig. 4).
# Included in the WHO-recommended composition of influenza virus vaccines for use in the 2011/2012 northern hemisphere influenza season.
* Included in the WHO-recommended composition of influenza virus vaccines for use in the 2012 southern hemisphere influenza season.
Further information
The EuroFlu bulletin describes and comments on influenza activity in the 53 countries in the WHO European Region. Further information can be obtained from the WHO/Europe, WHO headquarters and European Centre for Disease Prevention and Control web sites.
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