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EuroFlu - Weekly Electronic Bulletin - Week 14 : 02/04/2012-08/04/2012 - 13 April 2012, Issue N? 441 (edited)
[Source: EuroFlu, full page: (LINK). Extracts, edited.]
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.
126 respiratory specimens were collected from SARI patients, of which 22 (17%) were positive for influenza: 20 were type A and 2 were type B. All influenza A viruses were subtyped: 17 as A(H3) and 3 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 14/2012, 37 countries reported a dominant virus based on both sentinel and non-sentinel detections.
16 countries reported influenza A or A(H3N2) as the dominant virus, 1 country reported co-dominance of influenza A(H3) and A(H1), 2 reported co-dominance of influenza B with influenza A(H3N2), and 1 country reported influenza B as the dominant virus.
17 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 14/2012, 1332 specimens from non-sentinel sources were reported positive for influenza: 1097 (82%) type A and 235 (18%) type B.
Of the influenza A viruses, 623 were subtyped: 606 (97%) as A(H3N2) and 17 (3%) as A(H1N1)pdm09.
Since week 40/2011, 36 341 influenza viruses from sentinel and non-sentinel sources have been typed: 33 385 (92%) were influenza A and 2956 (8%) were influenza B.
Of the influenza A viruses, 4335 were subtyped: 3956 (91%) as A(H3N2) and 379 (9%) as A(H1N1)pdm09.
Since week 40/2011, 9 countries (Germany, Italy, the Netherlands, Norway, Portugal, Romania, the Russian Federation, Sweden and the United Kingdom) have screened 566 influenza A(H3N2), A(H1N1)pdm09 and B viruses for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir.
No resistance was reported.
All of the 110 A(H3N2) viruses and 10 influenza A(H1N1)pdm09 viruses that were screened for susceptibility to adamantanes were found to be resistant.
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 1499 influenza viruses antigenically (Fig. 3).
16 countries (Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Latvia, Norway, Portugal, the Russian Federation, Spain, Sweden, Switzerland) have characterized 1066 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 14 : 02/04/2012-08/04/2012 - 13 April 2012, Issue N? 441
Low levels of influenza activity in most countries of the WHO European Region
Current situation: week 14/2012
Outpatient surveillance for ILI and ARI
37 countries reported on trends in clinical activity: 2 increasing, 7 stable and 28 decreasing.
Of the 37 countries reporting on the geographical spread of influenza: 15 reported no or sporadic activity; 13, local activity; 5, regional activity; and 4, widespread activity.
No country reported high or very high intensity while low and medium intensity were reported by 30 and 7 countries respectively.
Of the 19 countries that reported a threshold for the 2011/2012 season, the consultation rates were above the threshold in Latvia and Sweden only.
In Croatia, where no epidemic threshold is available, the clinical rates of influenza activity are elevated.
During week 14/2012 sentinel outpatient clinics collected 657 respiratory specimens, of which 199 (30%) tested positive for influenza viruses, a percentage that is lower than the previous week (35%).
Of these positive specimens, 123 (62%) were influenza type A and 76 (38%) were influenza B (Table 1, Fig. 1).
In the 10 countries testing 20 or more sentinel specimens, influenza positivity ranged from 5% to 41%, with a median of 26% (mean: 23%).
Low levels of influenza activity in most countries of the WHO European Region
Current situation: week 14/2012
- This issue is based on data for week 14/2012 reported by 45 Member States in the WHO European Region.
- Consultation rates continue to decrease with only 2 countries reporting consultation rates above their thresholds.
- The percentage of influenza-positive cases has decreased from 35% to 30% compared to the previous week.
- The number of hospitalizations due to severe acute respiratory infection (SARI) is stable but the SARI influenza-positivity rate is decreasing.
- The proportion of influenza B in sentinel specimens increased slightly but the overall number of influenza B detections was stable. Influenza A(H3N2) viruses continue to dominate.
- No resistance to neuraminidase inhibitors has been reported so far this season.
Outpatient surveillance for ILI and ARI
37 countries reported on trends in clinical activity: 2 increasing, 7 stable and 28 decreasing.
Of the 37 countries reporting on the geographical spread of influenza: 15 reported no or sporadic activity; 13, local activity; 5, regional activity; and 4, widespread activity.
No country reported high or very high intensity while low and medium intensity were reported by 30 and 7 countries respectively.
Of the 19 countries that reported a threshold for the 2011/2012 season, the consultation rates were above the threshold in Latvia and Sweden only.
In Croatia, where no epidemic threshold is available, the clinical rates of influenza activity are elevated.
During week 14/2012 sentinel outpatient clinics collected 657 respiratory specimens, of which 199 (30%) tested positive for influenza viruses, a percentage that is lower than the previous week (35%).
Of these positive specimens, 123 (62%) were influenza type A and 76 (38%) were influenza B (Table 1, Fig. 1).
In the 10 countries testing 20 or more sentinel specimens, influenza positivity ranged from 5% to 41%, with a median of 26% (mean: 23%).
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.
126 respiratory specimens were collected from SARI patients, of which 22 (17%) were positive for influenza: 20 were type A and 2 were type B. All influenza A viruses were subtyped: 17 as A(H3) and 3 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 14/2012, 37 countries reported a dominant virus based on both sentinel and non-sentinel detections.
16 countries reported influenza A or A(H3N2) as the dominant virus, 1 country reported co-dominance of influenza A(H3) and A(H1), 2 reported co-dominance of influenza B with influenza A(H3N2), and 1 country reported influenza B as the dominant virus.
17 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 ? 657 - 126 - 33651 - 3850
- Influenza A + B - 199 (30.3%) - 22 (17.5%) - 10366 (30.8%) - 587 (15.3%)
- Influenza A - 123 (61.8%) - 20 (90.9%) - 9207 (88.8%) - 560 (95.4%)
- Influenza B - 76 (38.2%) - 2 (9.1%) - 1159 (11.2%) - 27 (4.6%)
- Influenza A subtyped - 92 - 20 - 8312 - 525
- A (H1N1)pdm09 - 4 (4.4%) - 3 (15.0%) - 153 (1.8%) - 62 (11.8%)
- A (H3N2) - 88 (95.7%) - 17 (85.0%) - 8159 (98.2%) - 462 (88.0%)
- A (H1N1) - 0 (0.0%) - 0 (0.0%) - 0 (0.0%) - 1 (0.2%)
During week 14/2012, 1332 specimens from non-sentinel sources were reported positive for influenza: 1097 (82%) type A and 235 (18%) type B. Of the influenza A viruses, 623 were subtyped: 606 (97%) as A(H3N2) and 17 (3%) as A(H1N1)pdm09.
Since week 40/2011, 36 341 influenza viruses from sentinel and non-sentinel sources have been typed: 33 385 (92%) were influenza A and 2956 (8%) were influenza B.
Of the influenza A viruses, 4335 were subtyped: 3956 (91%) as A(H3N2) and 379 (9%) as A(H1N1)pdm09.
Since week 40/2011, 9 countries (Germany, Italy, the Netherlands, Norway, Portugal, Romania, the Russian Federation, Sweden and the United Kingdom) have screened 566 influenza A(H3N2), A(H1N1)pdm09 and B viruses for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir.
No resistance was reported.
All of the 110 A(H3N2) viruses and 10 influenza A(H1N1)pdm09 viruses that were screened for susceptibility to adamantanes were found to be resistant.
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 1499 influenza viruses antigenically (Fig. 3).
16 countries (Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Latvia, Norway, Portugal, the Russian Federation, Spain, Sweden, Switzerland) have characterized 1066 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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