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Expert group defines 5 risk levels to aid control of STEC in food


At the 10th International Symposium on Shiga toxin producing Escherichia coli infections (VTEC2018) held in Florence Italy 6-9 May 2018, experts from The Joint FAO/WHO Expert Meetings on Microbiological Risk Assessment (JEMRA) presented innovative work carried out in response to a request from the Codex Committee on Food Hygiene for information on STEC in food.

What are STEC?

Escherichia coli (E. coli) are bacteria commonly found in the intestines of humans and animals. Though most of these bacteria are harmless, others can cause serious illness. Some kinds of E. coli cause illness by making a toxin called Shiga toxin. These bacteria are called Shiga toxin-producing E. coli or STEC for short. There are many kinds (called serogroups) of STEC that can cause disease.

STEC infections are a substantial health issue worldwide. The World Health Organization estimates that in 2010, foodborne STEC caused over 1 million human illnesses and 128 deaths. Targeting interventions relies on determining the types of foods that cause STEC infections. While ruminants and other land animals are considered the main reservoirs for STEC, various large-scale outbreaks have been linked to other foods, in particular fresh produce and more recently flour. 

Codex Committee on food hygiene (CCFH)

CCFH works on matters relating to food hygiene for all foods and prioritizes areas where there is a need for microbiological risk assessment at the international level. In its request to JEMRA, CCFH wished to identify the global burden of disease due to STEC in order to determine which commodities to focus on in developing guidance.

At the core of why CODEX is a long-term success is the solid foundation on science and the use of the risk analysis principles.

The Chair of CCFH Dr Emilio Esteban, of the United States of America Department of Agriculture said: “JEMRA provides CCFH with the support needed to get the latest and most comprehensive worldwide status on the science surrounding a particular interest.  JEMRA’s impartial and all-inclusive expert elicitation and discussion process, is a transparent mechanism to get a full unbiased scientific perspective on STEC.”  

Extensive scientific review

JEMRA set up an expert group and carried out an extensive scientific review to underpin the development of a set of criteria for categorizing STEC on a risk basis. Although there are hundreds of STEC serotypes, based on the evidence gathered during the review, the expert group concluded that the serotype of the STEC strain should not be considered a virulence criterion.  JEMRA therefore recommended a set of criteria for categorizing the potential risk of severity of illness associated with STEC in food based on evidence of virulence gene profiles and associations with clinical severity.

The set of criteria includes 5 risk levels (highest to lowest) based on virulence gene combinations, which can be used to identify risk management goals for STEC and the testing regimes that would be needed to monitor achievement of those goals.

Codex Senior Food Standards Officer Sarah Cahill, attending VTEC 2018, said: "This approach represents a change in paradigm in relation to management of STEC.  It is well recognized that STEC is a complex group of organisms so these efforts to try and simplify the identification of the strains of greatest risk was well appreciated. Application of this approach will support harmonization of risk management of STEC and with experience in application and the data and information that generates, the categorization can be further refined and improved.

Did you know?

Emilio Esteban

From the operational aspect, JEMRA is the microbial risk assessment body for CCFH.  It is critical for sustaining the scientific integrity of the Codex Alimentarius process, that we clearly separate the risk assessment process (JEMRA) from the risk management process (CCFH) thus minimizing the likelihood of introducing bias into the final guidelines. 

In essence, the risk managers from CCFH formulate the questions and the risk assessors from JEMRA provide the answers.  This system provides Codex with transparency and scientific integrity.

Emilio Esteban – Chair CCFH


Learn more

JEMRA and microbiological risks:

WHO factsheet on E-coli: