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Eurosurveillance, Volume 7, Issue 45, 06 November 2003
Articles

Citation style for this article: Paget WJ, Fleming DM, Meijer A, Samuelsson S, Schweiger B. Low but increasing levels of influenza activity in Europe: an update from EISS, week 43. Euro Surveill. 2003;7(45):pii=2319. Available online: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=2319

Low but increasing levels of influenza activity in Europe: an update from EISS, week 43

John Paget (j.paget@nivel.nl), NIVEL, the Netherlands; Douglas Fleming, Royal College of General Practitioners, United Kingdom; Adam Meijer, NIVEL, the Netherlands; Susanne Samuelsson, Statens Serum Institut, Denmark; and Brunhilde Schweiger, Robert Koch-Institut, Germany, on behalf of EISS

In the week ending 26 October 2003, Scotland reported local influenza activity* to the European Influenza Surveillance Scheme (EISS, www.eiss.org) (1). Sporadic but increasing influenza activity was reported in England, the Republic of Ireland and Spain, although usual winter baseline incidence levels were not exceeded. Sporadic activity and stable or decreasing clinical incidence rates were reported in France and Portugal, and 11 networks reported no influenza activity (that is, the overall level of clinical activity was at baseline levels). The Czech Republic, England, Republic of Ireland, Scotland and Spain all reported that clinical incidence rates were increasing compared with week 42/2003, and eight networks reported that they were stable.

Influenza A(H3N2) was the predominant virus circulating in France, Portugal and Spain, and influenza A (unspecified) was predominant in England and Ireland. Nine networks reported that there was no predominant virus circulating in the population.

The total number of respiratory specimens collected by sentinel physicians in Europe during week 42/2003 was 287. The percentage of specimens that tested positive for influenza was 13%, ranging from 0% (in 10 networks) to 40% (Republic of Ireland). Of the 37 positive specimens, 26 were cases of influenza A(H3N2) and 11 were cases of influenza A (unsubtyped).

So far this season (weeks 40-43/2003), sentinel physicians participating in EISS have collected 834 respiratory specimens and 98 have tested positive for influenza (12%). All of the positive cases have been cases of influenza A (55 cases of influenza A(H3N2) and 43 cases of influenza A (unsubtyped)). The influenza B virus has not been detected in sentinel (or non-sentinel) respiratory specimens so far this season.

EISS collects data on the cumulated number of sentinel and non-sentinel virus isolates that have been characterised during the 2003-2004 season. In week 43/2003, seven strain characterisations were reported to EISS and all seven were the new drift variant A(H3N2)/Fujian/411/2002 (four in England and three in the Republic of Ireland). Northern Ireland reported one case with this strain variant in week 42/2003, and so eight cases of this new drift variant have been reported to EISS so far this season, all from Great Britain and Ireland.

The new drift variant A(H3N2)/Fujian/411/2002 was the predominant virus circulating in Australia and New Zealand during the recent (southern hemisphere) influenza season, and activity during this season was relatively high in both countries (2). The A/Fujian-like viruses are related to the A/Panama-like (H3N2) strain included in the current 2003-2004 vaccine (3,4) and antibodies induced against this vaccine strain cross react with A/Fujian-like strains, but generally to a reduced level (2). On the evidence available so far, it is to be expected that the vaccine will also offer some cross protective immunity to the drift variant A/Fujian-like viruses. Influenza vaccination remains the most important intervention to limit influenza infection. Since the vaccine is composed of A(H1), A(H3) and B strains (3,4), it also offers protection against A(H1) and B viruses that might co-circulate with the A(H3) viruses or become dominant. The spread of influenza virus strains and their epidemiological impact in Europe will be carefully monitored by EISS in collaboration with the World Health Organization Collaborating Centre in London.

The EISS Weekly Electronic Bulletin presents and comments on influenza activity in the 19 European countries (22 networks) that are members of EISS. In week 43/2003, 17 networks reported clinical data and 14 networks reported virological data to EISS. The bulletin with epidemiological and virological data for week 44/2003 will be available on the EISS website (http://www.eiss.org/cgi-files/bulletin_v2.cgi) on 7 November.

*This indicates that increased influenza-like illness activity was reported in local areas (for example, a city) within a region of Scotland, or that outbreaks were reported in two or more institutions within a region, with laboratory confirmed cases of influenza activity. The levels of activity in remainder of the region, and other regions of Scotland, remained at or below baseline levels during week 43.

Map. geographical spread of influenza and the intensity of activity as assessed by each of the networks in EISS. Week 43 : 20/10/2003-26/10/2003. Source: EISS. For an interactive version of this map, see reference 1

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.

 

References:
  1. European Influenza Surveillance Scheme. Low but increasing influenza activity. EISS Weekly Electronic Bulletin 2003; Week 43: issue 95: 20/10/2003-26/10/2003. (http://www.eiss.org/cgi-files/bulletin_v2.cgi?display=1&code=95&bulletin=95) [accessed 6 November 2003]
  2. WHO Collaborating Centre for Reference & Research on Influenza, Melbourne, Australia. Outbreak of influenza reported throughout Australia. News item, September 2003. (http://www.influenzacentre.org/index.htm) [accessed 6 November 2003]
  3. WHO. Recommended composition of influenza virus vaccines for use in the 2003-2004 influenza season. Wkly Epidemiol Rec 2003; 78: 58-62. (http://www.who.int/wer/2003/en/wer7809.pdf)
  4. WHO. Addendum to the recommended composition of influenza virus vaccines for use in the 2003-2004 influenza season. Wkly Epidemiol Rec 2003; 78: 77. (http://www.who.int/wer/2003/en/wer7811.pdf)

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