List of
Lectures Return to
Title Page
|
INDEX
THE CONTEXT FOR SURVEILLANCE DEVELOPMENT
About 5 years ago, the Maastricht Treaty was signed which stated "the community shall contribute towards ensuring a high level of human health protection by encouraging co-operation between Member States and, if necessary, lending support to their action." This gave the European Commission "competence" in public health. In signing this treaty, Prime Ministers and Presidents agreed that public health was a matter to be taken forward on a European-wide basis. Therefore the political will and consequently funding become available to take things forward.
The most recent biomedical research and development budget (BIOMED I) of the Commission was 336 million Ecus. An Ecu is roughly equivalent to a dollar. About 10% of that could fund public health research and development.
Effective surveillance for infectious diseases is characterized by:
- Practicability
- Uniformity rather than complete accuracy
- Timeliness
The most effective surveillance systems are developed as a partnership of those who:
- Provide the data
- Collate, analyze, and interpret the data
- Disseminate the resulting information
- Have responsibility for public health action
Equal Partnerships
If surveillance systems are going to work well, partnerships of all those involved in the process must exist. Those who actually provide the data must play a part in designing the operational protocol and defining the output of the system. Those at the centre who collate, analyze and interpret the data must also work closely with those who use the data and the information for public health purposes.
Define Objective
Effective surveillance systems should always have defined objectives and there should be an entirely explicit operational protocol. It is essential at the European level that standard clinical and laboratory case definitions are used but this is not easy to achieve internationally. It is also important to be able to get back to individual cases for follow up, to adequately cover the population, and to distribute information in a timely way so that public health action takes place.
The Main Objectives of Surveillance at the European Level
- · The first objective is rapid detection of untoward events, unusual clusters, unusual syndromes or outbreaks, which will result in rapid investigations and appropriate public health action.
- · The second, to monitor trends over time to assess the need for interventions and to inform those who are responsible for developing policy at the European level.
THE PROCESS
A. Establishing a Starting Point
Eurosurveillance
1. The Start
As Ministers prepared to sign the Maastricht Treaty, I put a proposal to the European Commission in collaboration with Professor Elzinga from Rijksinstituut voor Volksgezondheid en Milieuhygiene (RIVM), the Netherlands national surveillance center, for a grant to draw up an inventory of all the international surveillance and training collaborations that were currently taking place in the European Union. We wanted to undertake a critical appraisal of the strengths and weaknesses of the various systems and determine whether there was a clear advantage in joint action at the international level on top of national surveillance. Some diseases are best dealt with at the national level, for example cryptosporidiosis whereas for others, such as legionnaires' disease, there is a clear 'added value' in also operating surveillance at the international level.
2. The Inventory
Two colleagues went to each of the then 12 European Union countries to visit the national centres to draw up a list of collaborations already in place to complete a standardized questionnaire on each. Then we invited experts from each of the European Community countries, the heads of institutions with responsibility for national surveillance, or their nominees, to evaluate each scheme according to a series of parameters. This critical appraisal was undertaken at a meeting convened at CDSC London in December 1993. The World Health Organization was represented at the meeting.
3. Results of the Inventory Appraisal
All agreed that there was a need to take forward collaborations at the European level. We felt we had to make that recommendation to the Commission. The reasons that were particularly important for Europe but also apply on a global basis, include:
- increased population mobility, the massive numbers of people moving for economic and political reasons, for tourism and for business;
- the open market in foods and other goods;
- the resurgence of 'old' infectious diseases, such as diptheria, TB, polio, cholera, and sexually transmitted diseases, particularly in Eastern European countries; and
- the emergence internationally of newly recognised infections such as those due to verocytotoxin-producing strains of E.coli.
Gaps and Overlaps
When we looked at the inventory, we found some surprising gaps. Diseases which you would consider to be of high priority, such as food-borne diseases, were not being kept under active surveillance at the European level. And there were some overlaps; for one disease there were three separate systems in place. It was quite clear that strategic development of surveillance was needed with an action plan that addressed priorities.
Quality of Surveillance
We found that there was variability in the quality of surveillance systems particularly in terms of standardisation of methods, timeliness, and the extent to which they were used to inform public health action. Several had become ends in themselves. In other words, information was exchanged, but just amongst the particular participants. This may be a good basis for collaborative research, but it is not surveillance as we mean it, with information leading to public health action.
Expert Advice
The European Commission, whilst it had acquired competence in public health, had few trained public health doctors, microbiologists or infectious disease physicians in its bureaucracy. We felt they needed a source of expert advice as well as the advice they received from national governments. We recommended that people with responsibility for national surveillance, in other words the heads of the national surveillance centres, meet twice a year to develop proposals for the strategic development of surveillance, including prioritisation, at the European Union level and facilitate implementation. The Commission agreed to fund such meetings and the "Charter Group" was established.
B. Activities of the Charter Group
The 15 heads of the national centers in the now enlarged European Union have met at regular intervals. A Working Group consisting of a representative from the Netherlands, Denmark, Portugal, France and the UK was established together with a small technical co-ordination unit with a medical epidemiologist based at CDSC. This group did much of the work in preparing high quality papers for the 15 heads of surveillance to take decisions and make recommendations. A report from the Charter Group was presented at a Forum to a broad international audience of people closely involved in surveillance (medical microbiologists, general public health doctors, clinicians) to gain support for what we were proposing and to inform them about the developments.
C. Benefits to International Surveillance
Operating surveillance at the international level allows early detection and the opportunity to provide early warning of threats to health. Untoward events can be recognized early through pooling and rapid analysis of data. Problems may be detected which might not be apparent in any one country. When international co-ordinated action is required, all EU countries now collaborate in investigating epidemics where disease specific networks have been established. International surveillance enables a country to evaluate national programs and improve its evidence based guidance. The whole process has helped to raise standards. In Europe there is considerable variation in cultures, type of health system and degree of investment in public health. In working together, we have identified priorities at the international level which may differ from priorities at the national level.
D. The Vision Exercise
To determine where we wanted to see surveillance at the European level in 5 years time and how the Charter Group foresaw getting there we used the Delphi technique to identify areas of consensus. The plan was to start work in the first few years where there was a clear consensus and tackle the more problematic areas later.
Eurocenter or Network of Networks
One key question considered in the vision exercise was whether Charter Group members wanted to see a "CDC for Europe" or a "network of networks". Everyone favored developing a network of networks, drawing on the strengths of each country. Modern information technology allows information sharing so easily that pulling resources together at one single point, was likely to be unnecessarily expensive and inefficient. Although the Charter Group has proceeded with this strategy in mind, in the end, it is the highest political level which will take the decision. [Since this presentation was prepared the European Parliament, Council and Commission have agreed that an epidemiological network will be created legally, rather than a Eurocenter for Disease Surveillance and Prevention.]
The Charter Group is developing jointly agreed standards for disease surveillance and has completed prioritization exercises. Infrastructure developments are being piloted and a series of disease-specific networks have been established.
Surveillance Infrastructure
The European Commission is investing large sums of money in an electronic communication system - the Interchange of Data between Administration (IDA). An electronic network will link many agencies in the 15 countries not just to the health organizations.. A rapid user survey was organised by the Charter Group of those exchanging information on communicable diseases, their priorities, and the types of information they wished to exchange. The survey found that relatively small volumes of data required to be exchanged on a day to day basis. The commercial contractor had been planning on a need to transmit large volumes of data. The Commission took note of the survey and required the company to modify its planned design. A highly flexible internet-based system with encryption with a central node is being built. Two EU surveillance networks, EWGLI and SalmNet, are being used to pilot the communicable disease module.
Surveillance Bulletins
For many years we have exchanged national surveillance bulletins. The Charter Group felt that the key way forward was to get the editors of each of the EU publications together, and 'EuroSurveillance', a new monthly European Bulletin is the product of 15 editors. Each editor provides the necessary clearance for information to be published at the European level. The most recent development is a weekly electronic bulletin to provide more timely information on events. Readers may access this bulletin on http://www.eurosurv.org. We hope that once the evaluation takes place in about six months time, this will be funded on a long-term basis. The monthly and weekly bulletins are co-ordinated by the Réseau National de Santé Publique (RNSP) in Paris and CDSC in London.
Training
The European Program for Intervention and Epidemiology Training (EPIET) has been in place for three years, co-ordinated initially by the Institute of Hygiene and Epidemiology in Brussels and from 1998 the RNSP in Paris. This has some similarities with the Epidemic Intelligence Service (EIS) in the USA and the global program operated by CDC. The purpose of EPIET is to train a group of public health doctors and epidemiologists to the same methods, standards and ethos, who all know one another and know the national centers well. These trained individuals will operate naturally at the European level in surveillance activities and response.
Some joint training initiatives and joint field investigations with American counterparts have occurred. In 1997 EPIET Fellows and EIS officers took part in an investigation of monkey pox in Zaire in a team led by WHO.
SPECIFIC SURVEILLANCE SYSTEMS
Several disease specific networks have been established in Europe in recent years. The responsibility for co-ordinating networks is shared amongst the national surveillance centers. I will describe two such networks which are currently co-ordinated by CDSC from London.
1) Legionnaire’s Disease Surveillance
This infection is contracted from an environmental source, such as a cooling water system or a hot water system, through the inhalation of contaminated water droplets. If the infection occurs in a hotel or cruise line in country A, the disease may not evolve until the infected person returns home. If information is pulled together on any travel-associated cases in European countries, outbreaks may be recognized at the earliest possible stage. In 1987 the European Working Group on Legionella Infection (EWGLI) established an active surveillance scheme, initially co-ordinated by the National Bacteriology Laboratory, Stockholm, and since 1993 by CDSC. 30 European countries now participate in the network. The main purpose of this scheme is to detect outbreaks rapidly and undertake a collaborative investigation to ensure that timely control measures are applied.
Case Definitions
Strict clinical and microbiological case definitions are necessary for this scheme to work effectively. The internationally agreed definitions published in the World Health Organization's Memorandum1 are used for this purpose.
Results
In 1996, there were 14 clusters of 2 or more cases. Clusters refer to people who within a six month period have stayed in the same premises, in the same hotel. Whenever there is a cluster, an investigation takes place and the hotel owners are advised about appropriate maintenance of the water systems. Those cases that appear year after year in association with the same hotel but outside the 6 month limit are called linked cases. 1,077 cases have been reported since 1987, including 111 clusters of 2 or more cases. One third of those clusters would not have been recognized through national surveillance alone.
One of the critical components of this scheme is timely reporting of information to the EWGLI co-ordinating center at CDSC. As soon as a cluster is detected, all collaborators, and the ministry of health in the source country are informed. This has often led to the identification of the source of the infection and the application of control measures.
Laboratory Developments
A good quality assurance scheme for the clinical diagnosis and for culturing legionella from the environment are in place. Different genotyping methods are being evaluated to develop two standard genotyping systems for Europe. One is likely to be relatively low-resource intensive, and applicable in most countries, and one more resource-intensive to provide the definitive genotyping that will be used for final identification.
Annual Workshop
EWGLI members have met annually to review methods and results and to plan further collaborative work. A strong 'esprit de corps' has been created amongst the membership by this means.
SalmNet
Another active laboratory-based surveillance system in Europe is SalmNet. In this network there are two collaborators in each country, the head of the national Salmonella reference laboratory, and the person responsible for national surveillance of salmonellosis. Similarly, we have two project leaders, an epidemiologist and a microbiologist.
These are the main characteristics of SalmNet:
- An international laboratory-based surveillance scheme for human Salmonella infections
- A timely on-line database of individual Salmonella isolates
- Standardized microbiological typing
- A BIOMED I concerted action-through DG XII funding
An annual meeting of collaborators has been important in determining the success of this network. This has provided the opportunity to review successes, discuss development of the operational protocol, and build up trust amongst participants.
SALM-NET Objectives include
- standardization of laboratory methods
- introduction of an international quality assurance scheme
- establishment of an international database
- creation of a core set of data items for each isolate
- application of an electronic communications system to update the database
- development of an automated mechanism for detecting clusters
- bringing such clusters rapidly to the attention of collaborators
Three areas were identified on which to make progress in the first three years: 1) microbiology; 2) epidemiology, and 3) a rapid response early warning system.
1) Microbiology
Three main Salmonella serotypes in Europe are a) Salmonella enteritidis (75%) b) Salmonella typhimurium and c) Salmonella virchow.
Agreement was reached on a single European phagetyping scheme for S.typhimurium and S. virchow in 1994 and the methodology for developing a common typing scheme for S. enteritidis in 1995..
2) Epidemiology
We wanted data that would enable us to detect untoward events and trends. Currently, the protocol requires monthly reporting and updates. The following are the agreed fields in the database specification:
- Country
- Serotype
- Phage type
- Specimen
- Sex
- Date of report
- Region
- Age
- Travel
- Food implicated
These data are now on the central database for EU countries plus Switzerland and Norway. An algorithm has been developed to automatically detect untoward events, taking into account the overall time trends and seasonal patterns. Observed and expected reporting levels are presented, together with the upper and lower confidence levels. We can print out the different types of Salmonella by rank order of excedance score to identify the ones that we need to investigate as a priority.
3) Early Warning System
In addition to the automatic system, collaborators are encouraged to inform the SalmNet co-ordinating centre whenever an unusual salmonella event is recognised in their country. This information is relayed on to all collaborators who are asked to report back if they are seeing a similar event in their own country. This mechanism has been effective in detecting international outbreaks at an early stage.
International Outbreaks Recognised and Investigated by SALM-NET
| Outbreak |
No of cases |
Countries with cases |
| E. coli / HUS |
12 |
Denmark, England & Wales, Finland, Sweden |
| S. anatum |
24 |
Eire, England & Wales, France, Scotland |
| S. agona |
2000+ |
Canada, England & Wales, Israel, USA |
| S. dublin |
30+ |
France, Switzerland |
| S. stanley |
100+ |
Finland, USA |
| S. tosamanga |
28 |
Eire, England & Wales, France, Germany, Sweden, Switzerland |
| Shigella sonnei |
100+ |
England & Wales, Germany, Norway, Scotland, Sweden |
S. tosamanga isolations in Europe 1995
| Country |
1995 isolates |
Previous history |
| Switzerland |
9 |
Never isolated |
| Sweden |
9 |
No known isolation |
| Ireland |
3 |
Not known |
| England & Wales |
3(+1)* |
No isolates in previous 33 yrs |
| Germany |
2 |
Not known |
| France |
1 |
Not known |
| *England & Wales - human isolate +1 non-human isolate |
Collaborative investigation of outbreaks
SalmNet has been used to investigate a number of outbreaks including salmonellosis associated with baby milk. In addition, the network was used to investigate an outbreak of shigellosis in adults, particularly young adults. Analytical epidemiology using phenotyping and genotyping results led to the identification of a common source, iceberg lettuce. The contaminated lettuce was traced back to the source country where there had been a water shortage, so had been using contaminated river water for irrigation. Intervention was implemented and the problem resolved with no further outbreaks to date.
A Major International Outbreak Detected and Investigated through SalmNet (2,3)
An outbreak due to Salmonella agona was identified in England in January 1995. The normal incidence of infections from this serotype is 40 cases per year, but in the first few weeks of 1995 there were 27 cases.
The common thread for the majority of the early cases was eating kosher foods. Descriptive epidemiology suggested a suspect food item and a case-control study was done to determine whether the food item in question was responsible for the outbreak. This study showed an odds ratio of 87.8 for that particular food item, a ready-to-eat peanut flavored savoury snack. On this basis the Department of Health took public health action. The organism, S.agona, was isolated from packets of the snack; forty four (83%) of the packets examined from one batch were contaminated with this type of Salmonella.
Notification of the outbreak went out worldwide, and associated cases found in the USA, Canada and Israel. There had been a large outbreak in Israel which had started the previous September and was affecting young children. It was initially thought to be a poultry strain in Israel, so the food vehicle was not identified there until the report from SalmNet. Laboratory testing showed that the poultry strains were quite distinct from the epidemic strain cultured from cases of infection in humans and from the savoury snack.
The most likely explanation is that the peanut flavoring used to flavor the snack was contaminated, but this is only speculation. The manufacturer has since modified the process and improved its microbiological quality assurance scheme.
The Future of SalmNet: Development of EnterNet
In 1998 SalmNet is being extended into a surveillance network called EnterNet which will incorporate the surveillance of E. coli 0157:H7 infections as well as the surveillance of salmonella infections and their antimicrobial resistance patterns.
EnterNet Objectives
- Continue the existing SalmNet surveillance system
- Collect data on the antimicrobial resistance of human salmonella isolates
- Facilitate the study of Salmonella resistance mechanisms
- Extend the typing of VTEC 0157 isolates
- Create an international database which is regularly updated and readily available to each participating team.
- Detect clusters of human isolates and inform participants rapidly
- Pilot an international quality assessment scheme for the identification/typing of VTEC 0157
This year several other countries may join the network, including the United States, Canada, Japan, Australia, South Africa, Israel and others. Several Eastern/Central European countries, including Latvia, Hungary, Poland and Czech Republic also wish to join.
EU-USA Task Force
The EU-USA Task Force on communicable disease was established through an accord signed between President Clinton and President Santer of the EU in May 1996. The USA has signed a number of bilateral agreements, including one with Canada, another with Japan, as well as the one with the European Union.
Task Force purposes:
- To establish concrete mechanisms for co-operation and coordination between the USA and EU and its member states.
- To strengthen collaboration with other countries, WHO and other international organizations.
- To take account of the concerns of developing countries and to assist in strengthening their technical capacity.
The Task Force has formed three working groups, one for surveillance and response, another for research and research training and the third for capability building. The Surveillance Response Working Group has begun work on three pilot areas - foodborne disease surveillance, antimicrobial resistance surveillance and joint training/field investigations. The Working Group hopes to strengthen links and involve them in several of the networks in 1999.
CONCLUSIONS
The experience in the EU has shown that several factors help to secure success in developing international surveillance and response systems.
- Political support, and consequently directed funding.
- A dedicated project co-ordinator to drive the system.
- Clearly specified objectives and an operational protocol which are agreed by everyone. These should be reviewed on an annual basis.
- Collaboration rather than competition amongst participants.
- High quality laboratory support using standard methods.
- An annual workshop for network participants to review successes and failures, develop methods and build trust.
- Most importantly, the information from the network has to be used to direct public health action
Readings: 1. Bulletin of the World Health Organization:1990: 68(2): 155-164
2. D Killalea, LR Ward, D Roberts, J deLouvois, F Sufi, JM Stuart, PG Wall, M Susman, M Schweiger, PJ Sanderson, IST Fisher, PS Mead, ON Gill, CLR Bartlett, B Rowe. International epidemiological and microbiological study of outbreak of Salmonella agona infection from a ready to eat savoury snack - I: England and Wales and the United States. British Medical Journal; 1996:313:1105-7
(BACK)
3. Shohat T, Green MS, Merom D, Gill ON, Reisfeld A, Matas A, Blau D, Gal N, Slater PE. An international outbreak of Salmonella agona infection caused by contamination of a ready-to-eat savoury snack: II - Israel. British Medical Journal; 1996:313:1107-9
(BACK)
Hastings L., Vurnens A, De Johg, B, Ward L, Fisher I, Stuart J, Bartlett C, Rowe B. "Salm-Net facilitates collaborative investigation of an outbreak of Salmonella tosamanga infection in Europe". Communicable Disease Report, Vol. 6, 1996.
Return to Title PageHOME | List of Lectures |
