EuroFlu - Weekly Electronic Bulletin - Week 51 : 19/12/2011-25/12/2011 - 30 December 2011, Issue N° 425
Sporadic influenza detections in the WHO European Region
- This issue is based on data for week 51/2011 reported by 44 Member States in the WHO European Region.
- The levels of influenza activity in the Region were low.
- Sixty-six sentinel specimens (8%) from patients with influenza-like illness (ILI) or acute respiratory infection (ARI) tested positive for influenza.
- The percentage of sentinel samples that were positive has increased during the past two weeks and indicates the possible start of the influenza season.
- Sporadic detections of influenza A(H3N2), influenza B and influenza A(H1N1)pdm09 have been reported since week 40/2011.
- All 101 influenza A viruses subtyped in week 51/2011 were A(H3).
Current situation: week 51/2011
Consultation rates for ILI and ARI are at pre-season levels in most countries in the WHO European Region.
Of 35 countries reporting on trends in respiratory disease activity, 20 reported stable trends, 6 reported increasing trends and 9 reported decreasing trends.
Of the 35 countries reporting on the geographical distribution of influenza activity, 21 reported no activity, 1 reported local activity and 13 reported sporadic activity.
In week 51, data from sentinel hospital-based surveillance for severe acute respiratory infection (SARI) were reported by 10 countries: Albania, Armenia, Georgia, Kazakhstan, Kyrgyzstan, the Republic of Moldova, Romania, the Russian Federation, Serbia and Ukraine.
Although some countries have been reporting slight increases in SARI cases in recent weeks, none of the cases reported this week were associated with laboratory-confirmed influenza.
Further information on the sentinel SARI surveillance systems represented in the EuroFlu bulletin can be found in the overview of sentinel SARI systems in EuroFlu.
Virological situation: week 51/2011
Sentinel outpatient clinics collected 801 respiratory specimens, of which 66 (8%) tested positive for influenza viruses: 62 were type A and 4 were type B.
All 61 type A viruses subtyped were identified as influenza A(H3).
In the 11 countries testing 20 or more sentinel specimens, influenza positivity ranged from 0% to 24% (Turkey).
Among these countries, France, Germany, Italy, Spain and Turkey have observed slight increases in influenza activity in recent weeks.
Only in France has the rate for ARI exceeded the baseline level.
In addition, 97 non-sentinel specimens were reported positive for influenza: 86 as type A and 11 as type B.
Of the influenza A viruses, 40 were subtyped: all were A(H3).
Sentinel hospitals collected 81 respiratory specimens from patients with SARI, none of which tested positive for influenza virus.
Cumulative virological data: weeks 40-51/2011
During this period, 733 influenza virus detections were reported: 631 (86%) were influenza A and 102 (14%) were influenza B.
Of the influenza A viruses, 428 were subtyped: 389 (91%) as A(H3) and 39 (9%) as A(H1)pdm09.
Since week 40/2011, 19 influenza viruses have been characterized antigenically:
Of 27 influenza viruses characterized genetically,
- 2 were A(H1)pdm09 A/California/7/2009 (H1N1)–like,
- 13 were A(H3) A/Perth/16/2009 (H3N2)–like,
- 2 were B/Florida/4/2006-like (B/Yamagata/16/88 lineage),
- 1 was B/Bangladesh/3333/2007-like (B/Yamagata/16/88 lineage) and
- 1 was B/Brisbane/60/2008-like (B/Victoria/2/87 lineage).
- 3 belonged to the B/Bangladesh/3333/2007 clade (Yamagata lineage),
- 1 belonged to the A(H1)pdm09 group represented by A/Astrakhan/1/2011,
- 1 belonged to the B/Brisbane/60/2008 clade (Victoria lineage) and
- 22 belonged to the A/Victoria/208/2009 A(H3) clade - 18 in the group represented by A/Stockholm/18/2011 and 4 in the group represented by A/Iowa/19/2010.
Influenza activity remains low throughout the WHO European Region.
For most countries, consultation rates for ILI and ARI in outpatient clinics and SARI admissions to hospitals are at pre-season levels.
Two countries (Spain and Turkey) reported increases in confirmed influenza cases among sentinel samples, with percentages of positive samples of 17% and 23% respectively, which could indicate that influenza activity is about to start in these countries.
Influenza has been detected sporadically during recent weeks, with 8% of sentinel samples collected across the WHO European Region testing positive for influenza in week 51/2011 – an increase from 5% in the previous week.
Sporadic detections of influenza A(H3N2), influenza B and influenza A(H1N1)pdm09 have been reported since week 40/2011.
Type A influenza has been dominant over type B, and in week 51/2011 all 101 type A viruses subtyped were A(H3).
The EuroFlu bulletin describes and comments on influenza activity in the 53 countries of the WHO European Region.
Further information can be obtained from the web sites of WHO/Europe, WHO headquarters and the European Centre for Disease Prevention and Control.
Country comments (where available)
Kazakhstan: In week 51/2011, 155 respiratory specimens were collected of which: 0 tested positive for influenza virus, 2 were adenoviruses, 3 respiratory syncytial viruses (RSV) and 3 parainfluenza-1.
Norway: Whereas the number of influenza virus detections in Norway remains comparably low, there has an increased number of influenza A detections in weeks 48 through 51. All except one out of 49 influenza A viruses subtyped in Norway so far this season have been of H3 subtype.
Romania: Laboratory investigations have been performed for 87% of SARI cases.
Detected pathogens were:
To date, the total positivity rate for SARI cases has been 52.2% and the positivity rate for influenza in SARI cases 0%.
- eleven parainfluenza virus type 1;
- two parainfluenza virus type 2;
- four parainfluenza virus type 4;
- three RSV type B;
- one untyped RSV;
- two adenovirus;
- two rhinovirus;
- two bocavirus;
- one Coronavirus 229E/NL63;
- one H.influenzae;
- seven Str.pneumoniae;
- one Ps.aeruginosa + Klebsiella spp.
In one of the two deaths registered in SARI cases, an adenovirus was detected.
For the second one, no samples have been prelevated (refusal of parents).
In the third death Pseudomonas aeruginosa and Klebsiella spp. have been isolated from tracheo-bronchial aspirate.