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19 Oct 2012

EuroFlu - Weekly Electronic Bulletin - Week 41 : 08/10/2012-14/10/2012 - 19 October 2012, Issue N° 458 (edited)

[Source: EuroFlu, full page: (LINK). Edited.]

EuroFlu - Weekly Electronic Bulletin - Week 41 : 08/10/2012-14/10/2012 - 19 October 2012, Issue N° 458

No evidence of increasing influenza activity in Europe


Summary week 41/2012

Influenza activity is at low levels in all countries in the WHO European Region.

All of the 14 countries that have established an epidemic threshold presented consultation rates for influenza-like illness (ILI) and/or acute respiratory infection (ARI) that were below their thresholds.

The number of severe acute respiratory infection (SARI) cases detected through hospital surveillance was similar to that in the previous week, but none of the 74 specimens tested was positive for influenza.

Nevertheless, the first sporadic detections from sentinel and non-sentinel sources were reported in weeks 40 and 41.

Most countries report no influenza activity and the percentage of samples testing positive is very low (<1%), indicating no significant influenza activity in the WHO European Region.

For a description of influenza surveillance in the WHO European Region. See below.


Virological surveillance for influenza

From sentinel sources, 3 out of 386 samples (0.8%) tested positive for influenza: 2 were influenza A (not subtyped) and 1 was influenza A(H3).

From non-sentinel sources, 3631 samples were collected and 18 (0.5%) influenza detections were reported: 6 influenza A not subtyped, 4 A(H3) and 8 B viruses.

Overall, a total of 21 samples tested positive for influenza in week 41/2012: 8 were influenza B and 13 were influenza A. Of the 13, 8 were not subtyped and 5 were A(H3) (Fig. 1).



Outpatient surveillance for ILI/ARI

ILI and ARI consultation rates are at usual levels for this time of year.

Of the 35 countries reporting on influenza intensity and spread, all reported low levels intensity; 31 reported no spread and 4 reported sporadic activity.

26 countries reported stable trends; 1 reported a decrease and 7 reported increases in influenza activity.

The proportion of ILI and ARI cases testing positive for influenza in the Region is low; of the 386 samples tested, 3 (0.8%) tested positive. See Fig. 2 for historical percentage positivity rates; no data are yet available for weeks 40 and 41, as for presentation at least 20 samples need to test positive for influenza.

Of 386 samples, 3 (0.8%) tested positive for influenza. 2 viruses were influenza A not subtyped and 1 was A(H3N2). Click here for a detailed overview of influenza virus detections by type and subtype since week 40/2012.


Hospital surveillance for SARI

Of 11 countries with SARI surveillance, 7 (Albania, Georgia, Kazakhstan, Republic of Moldova, Russian Federation, Serbia and Ukraine) reported hospitalizations due to SARI, with most cases occurring in the youngest age group (Fig. 3).

Of the 74 samples collected from hospitalized SARI cases, none tested positive for influenza. The samples were collected in 5 countries (Belarus, Georgia, Kyrgyzstan, Russian Federation and Ukraine).

Click here for a detailed overview of influenza virus detections by type and subtype since week 40/2012.


Monitoring of resistance to antiviral drugs

No viruses have been screened for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir this season.


Characterizations of virus strains

Influenza viruses are assessed each season for their antigenic and genetic characteristics, to determine the extent of their 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.

In the 2012/2013 northern hemisphere influenza season, WHO recommends the inclusion in the vaccine 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.


Description of influenza surveillance

The EuroFlu bulletin describes and comments on influenza activity in the 53 countries in the WHO European Region. Influenza activity is monitored through surveillance of ILI, ARI and/or hospital-based surveillance for severe disease. Primary care clinics conduct surveillance for ILI and/or ARI in most countries in the Region, although some countries routinely perform hospital-based surveillance. 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 and may not use a standard case definition for ILI, ARI or SARI.


Country comments (where available)

Republic of Moldova: This week were tested 8 samples from sentinel surveillance system: in one sample was detected RNA of hRSV and in one RNA of Parainfluenza virus type 2.