EISS - Introduction

	Contents: EISS Project: Introduction EISS (in French) EISS (in Spanish) EISS (in Portuguese) EISS (in Italian)

The European Influenza Surveillance Scheme

Introduction

Influenza is an important public health problem in the industrialised world. It is associated with higher general practice consultation rates [1], increased hospital admissions [2] and excess deaths [3]. It must also be considered in terms of health care planning, increased days lost due to absence from work and influenza pandemic planning [4]. Major worldwide influenza pandemics in the twentieth century occurred in 1918-20 (+20 million deaths), 1957-58 and 1968-70.

National networks for the clinical and virological surveillance of influenza have existed in Europe since the 1950s. In the late 1980s, efforts were made to improve the clinical reports from sentinel physicians by integrating virological surveillance systems [5] and by collecting data on a European level.

The first European influenza surveillance project was the Eurosentinel scheme (1987-1991), this was followed by the ENS-CARE Influenza Early Warning Scheme (1992-1995) [6, 7] and the European Influenza Surveillance Scheme (1996-) [8, 9]. The European Influenza Surveillance Scheme (EISS) has received funding from the Home & Consumer Protection Directorate-General of the European Commission since November 1999 and from industry since September 2000 (click here ).

Aim and objectives

The aim of EISS is:

To contribute to a reduction in morbidity and mortality due to influenza in Europe

The objectives of EISS are:

To collect and exchange timely information on influenza activity in Europe;
To aggregate, interpret and make publicly available clinical and virological data concerning influenza activity in Europe
To strengthen, and harmonise where appropriate, epidemiological and virological methods, primarily based on the integrated sentinel surveillance model, for assessing influenza activity in Europe;
To contribute to the annual determination of the influenza vaccine content;
To monitor influenza prevention and control policies in Europe, including influenza vaccine uptake;
To contribute to European planning and response to pandemic influenza through surveillance, investigation and provision of information;
To promote research in support of the objectives above;
And to establish and operate a Community Network of National Reference Laboratories for Human Influenza in Europe [click here].

Membership

EISS is funded by the European Commission and therefore aims to include all Member States of the European Union (EU). Full members must meet the following criteria:

The network is nationally or regionally representative;
The authority of the network is recognised by the national or regional health authority in the country or region;
Clinical surveillance and virological surveillance are integrated in the same population (community);
The network has functioned successfully for two years;
The network can deliver data on a weekly basis.

All 25 European Union Member States, Norway, Romania and Switzerland participate in EISS. The United Kingdom is represented by four surveillance networks: England, Northern Ireland, Scotland and Wales.

"Associate" members
Networks that do not fulfil all of the membership criteria are "associate" members of EISS. Ten networks are currently "associate" members: Austria, Cyprus, Estonia, Finland, Greece, Hungary, Latvia, Lithuania, Malta and Sweden. These networks either do not yet combine clinical and virological data in the same population or are in the process of adapting their surveillance system to meet the EISS membership criteria.

"Corresponding" members
The definition of a corresponding member is a country within the WHO European Region that is an associate member but has no official relation / status (Member State, candidate country / pre-accession country, etc) with the European Union.
Two countries are currently "corresponding members": Serbia and Ukraine.

Methods

The clinical surveillance of influenza in EISS is generally based on reports made by sentinel general practitioners (see Table 1). Some of the sentinel surveillance systems also include paediatricians (e.g. the Czech Republic, France and Germany) and physicians with other specialisations (e.g. Slovenia, Lithuania and Switzerland). The physicians usually represent 1-5% of physicians working in the country or region.

The case definitions and denominator populations used for the clinical surveillance of influenza vary by network [10; click here ]. Most sentinel surveillance systems report data on the number of new cases of influenza-like illness ( ILI ) and a few report the number of new cases of acute respiratory infection (ARI). Some networks report both ILI and ARI (Table 1).

The sentinel physicians are asked to take nose and/or throat swabs from patients with ILI or ARI. Some sentinel surveillance systems also collect blood samples (e.g. the Czech Republic, Romania and the Slovak Republic). The specimens are sent to the national reference laboratory and are tested for influenza viruses (if positive, subtypes are determined) and other respiratory viruses (e.g. respiratory syncytial virus) [11] - see Table 2. These results are used to validate the clinical reports of ILI and ARI [5].

The national reference laboratories also report influenza test results from non-sentinel surveillance physicians to EISS. Specimens (nose swabs, throat swabs and blood samples) can come from a wide range of sources: hospitals, non-sentinel physicians, homes for the elderly, clinics, etc. This data is collected to validate the data provided by the sentinel surveillance systems and to better describe the epidemiology and virology of influenza in each network.

Table 1: Characteristics of the sentinel surveillance systems participating in EISS

Country	Year network was started	Physicians (May 2004)	Numerator	Case definition
EU networks:
Austria	1950	42 GPs and 14 paediatricians (AGES network)	ILI	No
Belgium	1985	98 GPs	ILI+ARI	Yes
Cyprus		90 GPs	ILI	Yes
Czech Rep.	1968	2230 GPs and 1240 paediatricians	ARI	Yes
Denmark	1995	150 GPs	ILI	Yes
England	1964	360 GPs	ILI+ARI	No
Estonia		840 GPs	ILI	Yes
France	1984	378 GPs and 74 paediatricians	ARI	Yes
Germany	1992	604 GPs, 146 paediatricians and 33 internists	ARI	Yes
Greece	1999		ILI	Yes
Hungary	1937		ILI
Ireland	2000	68 GPs	ILI	Yes
Italy	1996	750 GPs and 100 paediatricians	ILI	Yes
Latvia		124 GPs	ILI	Yes
Lithuania	1997	321 GPs, 327 paediatricians and 396 therapeuts	ILI +ARI	No
Luxembourg	2003	15 GPs and 4 paediatricians	ILI +ARI	Yes
Malta	2002	11 GPs	ILI	Yes
The Netherlands	1970	67 GPs	ILI+ARI	Yes
Northern Ireland	2000	93 GPs	ILI	Yes
Poland	1946	192 GPs	ILI	Yes
Portugal	1989	170 GPs	ILI	Yes
Scotland	1971	90 GPs	ILI	Yes
Slovak Rep	1960	2121 GPs and 1202 paediatricians	ILI	Yes
Slovenia	1999	11 GPs, 14 paediatricians, 19 'community practitioners' for 7- to 18-year-olds	ILI +ARI	Yes
Spain	1994	391 GPs and 102 paediatricians	ILI	Yes
Sweden	1999	96 practices	ILI	No
Wales	1986	30 GPs	ILI	Yes
Other networks:
Norway	1975	201 practices	ILI	Yes
Romania	1992	240 GPs and 102 paediatricians	ILI+ARI	Yes
Switzerland	1986	154 GPs, 43 paediatricians and 68 internists	ILI	Yes
GPs = general practitioners ILI = influenza-like illness ARI = acute respiratory infection

Table 2: Characteristics of the virological surveillance systems participating in EISS

Country	Virus detection		(Sub)Typing	Variant analysis ^a
	Culture	Additional tests
EU networks:
Austria	MDCK	ELISA / RT-PCR	ELISA / HI / RT-PCR	HI / sequencing
Belgium	MDCK	NP / RT-PCR	ELISA / RT-PCR	sequencing
Cyprus
Czech Republic	CE / MDCK	ELISA / IP / NP / RT-PCR	ELISA / HI / IF / IP / RT-PCR	HI
Denmark	MDCK	ELISA / RT-PCR	HI / RT-PCR	WHO-CC London
England	MDCK / RMK	RT-PCR	HI / RT-PCR	HI / sequencing
Estonia
Finland	MDCK	RT-PCR / trFI	HI / trFI	HI / sequencing
France	CE / MDCK	ELISA / RT-PCR	ELISA / HI / NI / RT-PCR	HI / sequencing
Germany	CE / MDCK	ELISA / IF / NP / RT-PCR	HI / RT-PCR	HI / sequencing
Greece	MDCK	RT-PCR	RT-PCR	HI
Hungary	CE / MDCK		PCR
Ireland	MDCK	IF / RT-PCR	IF / RT-PCR	WHO-CC London
Italy	CE / MDCK	NP / RT-PCR	HI / NP / RT-PCR	HI / sequencing
Latvia	MDCK	ELISA / IF / RT-PCR	ELISA / HI / IF	WHO-CC London
Lithuania	CE / MDCK	IF	HI / IF	-
Luxembourg	MDCK	CFT / NP / RT-PCR	HI / NI / NP	-
Malta ^b	-	-	-	-
The Netherlands	CE / MDCK / TMK	IF / RT-PCR	HI / IF / RT-PCR	HI / sequencing
Northern Ireland	CE / MDCK	IF / RT-PCR	-	-
Poland	CE / MDCK	IF / NP / RT-PCR	HI / IF / RT-PCR	HI
Portugal	CE / MDCK	RT-PCR	HI / RT-PCR	HI / sequencing
Scotland	MDCK / LLC-MK2 / R-Mix	RT-PCR	RT-PCR	Sequencing
Slovak Republic	CE / MDCK	ELISA / IF / NP / RT-PCR	ELISA / HI / IF/ RT-PCR	HI
Slovenia	MDCK / MK	IF / RT-PCR	HI / IF / NI / RT-PCR	WHO-CC London
Spain	CE / LLC-MK2 / MDCK	ELISA / IF / RT-PCR	HI / IF / RT-PCR	HI / sequencing
Sweden	MDCK	RT-PCR	HI / IF / RT-PCR	HI / sequencing
Wales	RMK	IF / NASBA / RT-PCR	IF (typing only)	HPA London
Other networks:
Norway	CE / MDCK	NP / RT-PCR	HI / IF / RT-PCR	HI / sequencing
Romania	CE / MDCK	ELISA	HI / NI	HI
Switzerland	LLC-MK2 / MDCK	IF / RT-PCR	HI / IF / RT-PCR	HI
CE = embryonated Chicken Eggs CFT = complement fixation test EIA = enzyme immuno assay ELISA = enzyme-linked immunosorbent assay HPA = Health Protection Agency Laboratory HI = hemagglutination inhibition assay IF = immunofluorescence IP = immunoperoxidase staining MDCK = Madin Darby Canine Kidney MK = Monkey Kidney NASBA = nucleic acid sequence based amplification NI = neuraminidase inhibition assay NP = near patient test R-Mix = a mixed monolayer of mink lung cells (Mv1Lu) and human adenocarcinoma cells (A549) RMK = Rhesus Monkey Kidney RT-PCR = reverse transcriptase polymerase chain reaction TMK = Tertiary Monkey Kidney trFI = time-resolved fluoroimmunoassay WHO-CC = WHO Collaborating Centre for Reference and Research on Influenza ^a All laboratories send a subset of virus isolates to the WHO-CC, London, for confirmation and comparison with isolates from all over the world. ^b Malta is developing the laboratory and has currently only antibody testing available.

During the influenza season (week 40 to week 20 of the following year), clinical and virological data are collected on a weekly basis by each participating network. The data are processed, analysed and assessed before being entered into the EISS database using an Internet application [8]. The Internet application allows EISS members to view influenza activity in the other networks and to make detailed clinical and virological queries. Maps, figures, tables and data from the previous years can also be downloaded from the EISS database. This part of the Internet application is only accessible to authorised persons.

The EISS web site (www.eiss.org) has a number of public pages, which provide information on the surveillance scheme, useful links and the Weekly Electronic Bulletin. The Bulletin provides a weekly overview of influenza activity in Europe in the form of a map, a table, graphs and a commentary written by experts from the EISS group (click here). It is based on data entered into the EISS database by Thursday 12:00 (CET), it appears every Friday at 12:00 (CET) and it concerns data collected during the previous week.

Results

The 2005-2006 influenza season:

See the following sources of information:

EISS Weekly Electronic Bulletins (click here);
EISS maps for the previous three weeks (click here);
Historic graphs and maps (click here).

The 2004-2005 influenza season (taken from reference [12]):

Clinical influenza activity varied across Europe during the 2004-2005 season. In some countries clinical influenza activity was low (e.g. in the United Kingdom) and in a number of countries (Italy, the Netherlands, Slovenia, Spain and Switzerland) the peak of clinical activity was higher than in the previous seasons (e.g. the highest in five seasons in the Netherlands and in eight seasons in Spain). There was a general west-east spread of influenza activity across Europe at the beginning of the season changing into more of a south-north spread later on in the season. The highest clinical incidences were usually observed in the 0-4 age group, while in Belgium, Portugal, Slovakia, Spain and Wales, the highest clinical incidences were observed in the 5-14 age group. Influenza A(H3N2) viruses were dominant in most countries and a minority of detections were influenza A(H1N1) viruses. Influenza B viruses were particularly detected in the east of Europe, especially in Slovenia where 67% of the sentinel specimens were influenza B virus. By antigenic characterisation, many of the A(H3N2) viruses deviated slightly from the 2004-2005 vaccine strain A/Wyoming/3/2003: 40% of total characterised viruses were A/Wellington/1/2004-like and 19% were A/California/7/2004-like. In addition, of the characterised B viruses, 43% were B/Hong Kong/330/2001-like, a non-vaccine strain of the Victoria lineage of B viruses. The B viruses in Slovenia matched the vaccine strain B/Jiangsu/10/2003, a Yamagata lineage B virus. Although most of the influenza A(H3N2) viruses deviated slightly from the vaccine strain and Victoria lineage B viruses re-emerged this season, this had no particular impact on the levels of clinical influenza activity (total and age specific) in Europe.

The 2003/2004 influenza season: click here [13]
The 2002/2003 influenza season: click here [14]
The 2001/2002 influenza season: click here [15]
The 2000/2001 influenza season: click here [16]
The 1999/2000 influenza season: click here [17]
The 1997/1998 influenza season: click here [18]

Conclusions

EISS is a modern and efficient European surveillance system that collects high quality data, combining both clinical and virological information. By using an Internet-based platform, it is easily accessible and provides timely information. These two characteristics are very important as the scheme needs to be in a position to react to the emergence of a new influenza virus strain and a possible influenza pandemic in Europe .

EISS allows national experts to better assess influenza activity in Europe and provide more accurate epidemiological and virological information to their governments, health care professionals and the general public. Important future projects include: the further standardisation of the main indicators collected, virological [19] and clinical reporting [20] quality control studies, the further development of the Community Network of Reference Laboratories for Human Influenza (click here) and an active participation in the ViRgil project (a European Network of Excellence aimed at combating viral resistance to treatments) and a closer collaboration with the European Centre for Disease Prevention and Control.

References

Mc Cormick A, Fleming D, Charlton M. Morbidity statistics from general practice: fourth national study 1991-1992. London : HMSO 1995. (Series MB5 no 3).
Glezen WP. Serious morbidity and mortality associated with influenza epidemics. Epidemiological Review 1982; 4: 25-44.
Fleming DM. The contribution of influenza to combined acute respiratory infections, hospital admissions, and deaths in winter. Communicable Disease and Public Health 2000; 3: 32-38.
Paget WJ, Aguilera J-F on behalf of EISS (European Influenza Surveillance Scheme). Influenza pandemic planning in Europe . Eurosurveillance 2001; 6:136-140 [click here].
Fleming DM, Chakraverty P, Sadler C, Litton P. Combined clinical and virological surveillance of influenza in winters of 1992 and 1993-4. British Medical Journal 1995; 311: 290-291 [click here].
Snacken R, Bensadon M, Strauss A. The CARE Telematics Network for the surveillance of influenza in Europe . Methods of Information in Medicine 1995, 34, 518-522.
Fleming DM and Cohen JM. Experience of European Collaboration in Influenza surveillance in the winter 1993-1994. J. Public Health Medicine 1996; 18: 133-142.
Snacken R, Manuguerra JC, Taylor P. European Influenza Surveillance Scheme on the Internet. Methods of Information in Medicine 1998; 37, 266-270.
Aymard M, Valette M, Lina B, Thouvenot D, the members of Groupe Régional d'Observation de la Grippe and European Influenza Surveillance Scheme. Surveillance and impact of influenza in Europe . Vaccine 1999: 17: S30-S41.
Aguilera JF, Paget WJ, Mosnier A, Heijnen ML, Uphoff H, van der Velden J, Vega T, Watson JM. Heterogeneous case definitions used for the surveillance of influenza in Europe . European Journal of Epidemiology 2003: 18(8): 733-736.
Meerhoff TJ, Meijer A, Paget WJ on behalf of EISS. Methods for sentinel virological surveillance of influenza in Europe - an 18-country survey. Eurosurveillance 2004: 9(1): 1-4 [click here].
Paget J, Meijer A, Brown C, Meerhoff T, van der Velden K. Epidemiological and virological analysis of the 2004-2005 influenza season in Europe. Poster. The 13 th European Conference on Public Health, Graz (10-12 November 2005) [click here].
WJ Paget, TJ Meerhoff, A Meijer on behalf of EISS. Epidemiological and virological assessment of influenza activity in Europe during the 2003-2004 season. Eurosurveillance 2005;10(4):107-111 [click here].
Paget WJ, Meerhoff TJ, Rebelo de Andrade H on behalf of EISS. Heterogeneous influenza activity across Europe during the winter of 2002-2003. Eurosurveillance 2003: 8(12): 230-239 [click here].
Paget W, Meerhoff TJ, Goddard N on behalf of EISS (European Influenza Surveillance Scheme). Mild to moderate influenza activity in Europe and the detection of novel A(H1N2) and B viruses during the winter of 2001-02. Eurosurveillance 2002; 7: 147-1575 [click here].
Manuguerra J-C, Mosnier A, Paget W on behalf of EISS (European Influenza Surveillance Scheme). Monitoring of influenza in the EISS European network member countries from October 2000 to April 2001. Eurosurveillance 2001; 6: 127-135 [click here].
Manuguerra J-C, Mosnier A on behalf of EISS (European Influenza Surveillance Scheme). Surveillance of influenza in Europe from October 1999 to February 2000. Eurosurveillance 2000; 5:63-68 [click here].
Zambon M. Sentinel surveillance of influenza in Europe , 1997/1998. Eurosurveillance 1998; 3: 29-31 [click here].
Valette M, Aymard M. Quality control assessment of influenza and RSV testing in Europe : 2000-01 season. Eurosurveillance 2002; 7: 161-165 [click here].
Aguilera J-F, Paget WJ, van der Velden J. Development of a protocol to evaluate the quality of clinical influenza data collected by sentinel practitioners in Europe . Eurosurveillance 2002; 7: 158-160 [click here].

Written by the EISS co-ordination centre on behalf of the EISS Working Group.

Acknowledgements

EISS is funded by the DG Health & Consumer Protection of the European Commission. EISS also receives funding from Roche and Sanofi Pasteur.

EISS would not exist without the regular participation of the sentinel physicians across Europe. We would like to thank them for making this surveillance scheme possible.

Last updated: 18 December 2006