Influenza activity on the increase in a number of countries in Europe, in particular Belgium, France 2003-12-13

Influenza activity on the increase in a number of countries in Europe, in particular Belgium, France and Norway

Adapted from the EISS Weekly Electronic Bulletin, 48/2003 (reference 2) by the editorial team (eurowkly@phls.org.uk), Eurosurveillance editorial office

Clinical and virological data collected by the European Influenza Surveillance Scheme (EISS) for week 48/2003 suggests that the early influenza activity in Spain, Portugal, the United Kingdom (UK) and Ireland, predominantly caused by A/Fujian/411/2002 (H3N2)-like viruses (1), is slowing down and even declining in some of these countries (2). Influenza activity is currently increasing in a number of countries, in particular in Belgium, France and Norway. In many countries, the seasonal activity has not yet taken off, as networks report sporadic or no influenza activity.

Widespread influenza activity was reported in Belgium, England, France, Ireland, Norway, Portugal, Scotland, and Spain in week 48/2003, indicating that influenza activity was above the baseline level in all regions. Regional activity was reported in Switzerland and local outbreaks were reported in Northern Ireland. In the rest of Europe sporadic or no influenza activity was reported.

Map. Geographical spread of influenza as assessed by each of the networks in EISS. Week 48 : 224/11/2003-30/11/2003. Source: EISS. For an interactive version of this map, and other maps and figures, see reference 2.

 

Key:

A = Dominant virus A
H1N1 = Dominant virus (H1N1)
H3N2 = Dominant virus (H3N2)
H1N2 = Dominant virus (H1N2)
B = Dominant virus B
A & B = Dominant virus A & B

= : stable clinical activity
+ : increasing clinical activity
- : decreasing clinical activity

No activity = no evidence of influenza virus activity (clinical activity remains at baseline levels)
Sporadic = isolated cases of laboratory confirmed influenza infection
Local outbreak = increased influenza activity in local areas (e.g. a city) within a region,
or outbreaks in two or more institutions (e.g. schools) within a region. Laboratory confirmed.
Regional activity = influenza activity above baseline levels in one or more regions with
a population comprising less than 50% of the country´s total population. Laboratory confirmed.
Widespread = influenza activity above baseline levels in one or more regions with a population
comprising 50% or more of the country´s population. Laboratory confirmed.


The intensity of clinical incidence was high in Portugal, medium in eight networks and low in eleven networks. Increasing incidences were reported in Belgium, France, Switzerland, Italy, the Czech Republic and Sweden. Particularly strong increases were observed in Belgium and France, with both countries reporting widespread activity for the first time this season in week 48/2003.

Among the networks that have reported widespread activity earlier this season, Ireland, Scotland and Spain reported declining incidences, stable incidences were reported in England and increasing incidences were reported in Norway and Portugal. Influenza-like-illness or acute respiratory infection was most common in the youngest age groups (0-14), even in networks reporting few or no influenza virus detections.

The total number of respiratory specimens collected by sentinel physicians in week 48/2003 was 916. The percentage of sentinel specimens that tested positive for influenza virus was 31%, a similar percentage to week 47/2003 (31%). Of the sentinel and non-sentinel influenza virus isolates tested in week 48/2003, 935 were typed influenza A (754 unsubtyped and 181 H3N2) and five were typed influenza B (two in Ireland, one in England, one in Scotland and one in France). The H3N2 virus was predominant in ten countries and influenza A unsubtyped in four countries.

Based on the strain characterisation data available up to week 48/2003, 106 isolates were A/Fujian/411/2002 (H3N2)-like, six were A/Moscow/10/99 (H3N2)-like, and the hemagglutinin of five A/(H1N2) isolates (all in Norway) was A/New Caledonia/20/99 (H1N1)-like (click here http://www.eiss.org/cgi-files/figures2002.cgi?year=2003&week=48&region=Europe&type=v).[u2] The Fujian-like strain has been isolated in England (35), Norway (21), Spain (16), Denmark (9), Portugal (9), Ireland (8), the Netherlands (4), Switzerland (3) and Northern Ireland (1).

Seasonal influenza activity is gradually moving across Europe: it started in Ireland, the UK, Spain and Portugal, then moved to Norway, and is now in France and Belgium. In all of these countries, the predominant virus is the new drift variant A/Fujian/411/2002 (H3N2) and the highest clinical incidences are observed in the youngest age groups (0-14 years). There are signs that seasonal influenza activity is currently moving to other countries in Europe, for example, to Switzerland.

Influenza vaccination remains the most important intervention to limit the impact of influenza infection on high risk groups with either influenza A(H1), A(H3) or B strains currently circulating in the northern hemisphere. The A/Fujian/411/2002 (H3N2)-like viruses are related to the A/Panama/2007/99 (H3N2) strain included in the 2003-2004 vaccine. Based on the evidence available so far, antibodies induced against this vaccine strain are expected to provide valuable protection against infection with A/Fujian/411/2002 (H3N2)-like viruses.

References:
  1. Paget J, Fleming D, Meijer A, Samuelsson S, Schweiger B. Low but increasing levels of influenza activity in Europe: an update from EISS, week 43. Eurosurveillance Weekly 2003; 7(45): 6 November 2003. (http://www.eurosurveillance.org/ew/2003/031106.asp)
  2. European Influenza Surveillance Scheme. Low but increasing influenza activity. EISS Weekly Electronic Bulletin 2003; Week 48: issue 100: 24/11/2003-30/11/2003. (http://www.eiss.org/cgi-files/bulletin_v2.cgi?display=1&code=100&bulletin=100) [accessed 10 December 2003]