[Emerging Infectious Diseases]                                                         
[Volume 4 No. 3 / July - September 1998]

Special Issue

The U.S.EU Conference on Extension of the Salm/Enter-net Surveillance
System for Human Salmonella and Escherichia coli O157Infections(sup 1)

Alexandra Levitt
Centers for Disease Control and Prevention, Atlanta, Georgia, USA

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To help extend the European Union's (EU) Enter-net system for the
surveillance of Salmonella and Shiga toxin-producing Escherichia coli
(STEC)(sup 2) to other countries, a conference was held on March 12, 1998, 
under the auspices of the U.S.EU Task Force on Communicable Diseases. The
conference was cochaired by James LeDuc (Centers for Disease Control and
Prevention [CDC], United States) and Christopher Bartlett (Public Health
Laboratory Service [PHLS] Communicable Disease Surveillance Center [CDSC],
United Kingdom), who head the Task Force Working Group on Surveillance and
Response. Attendees from countries outside EU (South Africa, Hungary,
Canada, Japan, Poland, Australia, the Czech Republic, Latvia, and the
United States) were invited to describe their countries' procedures for
monitoring Salmonella and E. coli O157:H7.

Enter-net, which has superseded the EU's Salmonella surveillance system
(Salm-net), is an example of "globalization in action." The network
consists of the microbiologist in charge of the member nation's national
reference laboratory and the epidemiologist responsible for national
surveillance of foodborne diseases. A collaboration of epidemiologists and
microbiologists working at the technical level, the network is not a
regulatory organization. It includes participants from all 15 EU countries
plus Norway and Switzerland, with a combined population of 380 million.
Since 1994, Enter/Salm-net has detected 10 international outbreaks
resulting from contaminated food or water, including one that involved an
Israeli snack food contaminated with S. Agona and one due to S. Livingstone
infection in visitors to Tunisia. Enter-net's objectives are to extend
Salm-net monitoring to STEC, including E. coli O157:H7, as well as
drug-resistant strains of Salmonella.

Enter-net participants are working toward a common set of laboratory
protocols, including procedures for serotyping, phage typing, and toxin
typing. They report disease cases to the international Enter-net database
on a regular basis, through the Internet, by using standardized data
fields. Every year, the participants from each member country attend a
workshop to discuss technical issues and principles of collaboration.
Potential conflicts addressed at workshops include ownership of data;
confidentiality; outbreak control measures; and liability concerns (e.g.,
what happens when a food product is implicated by Enter-net as a vehicle of
disease transmission). At the next workshop, which will take place in
November 1998 in Denmark, Enter-net members will review protocols for
collaborative field investigations.

U.S. representatives described U.S. procedures for surveillance of
Salmonella and STEC, including procedures for antimicrobial resistance
monitoring. While Enter-net relies largely on phage typing to define E.
coli O157:H7 subtypes, pulsed-field gel electrophoresis (PFGE) is the
primary E. coli O157:H7 subtyping method in the United States. In 1996, CDC
initiated PulseNet, a national molecular subtyping network for tracking E.
coli O157:H7. PulseNet is being expanded to include Salmonella and other
foodborne pathogens. PulseNet currently includes 26 state and large city
health departments and laboratories from the U.S. Department of Agriculture
and the Food and Drug Administration. An electronic database at CDC will be
accessible to all participating PulseNet laboratories and will include DNA
patterns of foodborne pathogenic bacteria and epidemiologic information
associated with these isolates. Like Enter-net, PulseNet requires that all
reporting sites use harmonized laboratory methods and standardized
reporting specifications.

Each month, Enter-net's coordinator, based at the Communicable Disease
Surveillance Center, applies an automatic cluster-detection algorithm to
detect international outbreaks. To make the best use of the algorithm, each
country must supply Enter-net with retrospective data from at least 3
years. The United States has an analogous system, the Salmonella Outbreak
Detection Algorithm (SODA), which analyzes data reported through CDC's
Public Health Laboratory Information System (PHLIS). Some U.S. state health
departments are beginning to use SODA to perform their own analyses for
incident detection.

Over the past few months, Enter-net has begun to define the data that will
be collected on isolates of E. coli O157:H7; the data will be incorporated
in an international database similar to the one used for Salmonella. The
network has also begun a survey of methods in use for antimicrobial
resistance monitoring in its member countries.

Enter-net's goals for 1998 are to conduct an inventory of national
laboratory practices related to the diagnosis of STEC and to antimicrobial
resistance testing for STEC and Salmonella, perform a multicenter study in
participating reference laboratories on the detection of drug resistance,
upgrade the Enter-net database to include STEC and antimicrobial resistance
testing, agree on an outbreak investigation protocol, pilot weekly on-line
reporting, and hold a scientific workshop in Denmark in November 1998.

Formal invitations will be sent to non-EU countries that have expressed
interest in joining Enter-net. Pilot data exchanges will be initiated in
September 1998. If possible, new members will begin routine data exchange
by early October and will attend the November workshop in Denmark.

For additional information on Enter-net, contact Ian Fisher (e-mail:
ifisher@phls.co.uk), PHLS Communicable Disease Surveillance Centre, 61
Colindale Avenue, London NW9 5EQ, United Kingdom. For PulseNet, contact
Bala Swaminathan, National Center for Infectious Diseases, CDC, Mailstop
C07, 1600 Clifton Road, N.E., Atlanta, GA 30333, USA.

(sup 1)Summary presented at a satellite meeting, March 12, 1998.
(sup 2)Previously known as verotoxin-producing Escherichia coli (VTEC).

Emerging Infectious Diseases
National Center for Infectious Diseases
Centers for Disease Control and Prevention
Atlanta, GA

URL: ftp://ftp.cdc.gov/pub/EID/vol4no3/ascii/levi.txt

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