Select Committee on Health Appendices to the Minutes of Evidence

Attachment 5


  Food-borne disease is a major public health problem. Modern food distribution and manufacturing practice is that foodstuffs are now produced or harvested in one country and distributed internationally. This presents the opportunity for infections to emerge far from the source of contamination. A responsive surveillance system that can recognise and react to international outbreak of food-borne disease is essential. Enter-net—the international surveillance system for salmonella and Escherichia coli is such a system, and has been co-ordinated by the PHLS at the Communicable Disease Surveillance Centre in Colindale since its inception (as Salm-Net) in 1992.

  The threat of food poisoning from contaminated products is ever present, and successful surveillance depends on a partnership between microbiological and epidemiological experts. Surveillance is even more critical when vulnerable groups are affected. An example of this partnership is a recent outbreak of Salmonella anatum associated with consumption of infant milk formula. In late January 1997, 12 cases of S.anatum in babies under the age of one year were identified, eight in England and four in Scotland. The Communicable Disease Surveillance Centre and the Scottish Centre for Infection and Environmental Health under took a joint case-control study, which was completed within 48 hours. Results of the study implicated a particular brand of infant milk formula. International investigations through Enter-net revealed other associated cases in France and Ireland. Strains of S.anatum were subjected to an in-depth microbiological analysis. The analysis of strains from England, France and Scotland by pulsed-field gel electrophoresis (PFGE) showed that all the cases were the outbreak strain. A sample from an unopened packet of the implicated product was positive for S.anatum that had the same PFGE pattern.

  As a result of the epidemiological investigation, confirmed by the microbiological testing, the product was withdrawn from sale in both France and the UK. If these investigations had not been done so rapidly and efficiently the contaminated product would have been available for consumption for a considerable while longer. This would have exposed many more babies to the possibility of infection.


  The public health benefits of international surveillance networks such as Enter-net have been demonstrated many times. One of the strengths of these networks is that of the hub being based within the PHLS. This brings the benefit of epidemiological experience in outbreak investigation, microbiological expertise and contact with colleagues in sister institutes in other countries all working in harmony.


  The development of Enter-net needs to be ensured, and improved, by increasing the capacity of all participating countries to be able to sub-type food-borne pathogens using phenotypic and genotypic methods. This can be resolved by ensuring that appropriate submissions to the European Commission are made at the correct time. Development of new, rapid typing techniques is a key area of the future.


  The PHLS has identified that international surveillance for the benefit of public health is important and it has successfully fulfilled its role as a key player in this field. Public health requires a multi-disciplinary approach. By combining epidemiological and microbiological expertise, and fostering international collaboration, the PHLS is ideally placed to develop the surveillance of food-borne disease internationally.


  Ian Fisher on behalf of the Enter-net participants. The Enter-net international surveillance network—how it works. Eurosurveillance 1999; 4: 52-5.

  Prepared by Dr Ian Fisher (PHLS) on behalf of the Enter-net participants.

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Prepared 28 March 2001