Scientific Report
Shiga toxin-producing E. coli outbreak(s)
Between the beginning of May and the end of July 2011, there was an outbreak of Shiga-toxin producing Escherichia coli (STEC) in Germany. On 24 June 2011, French authorities also reported an E. coli outbreak in the region of Bordeaux. Since the start of these outbreaks, there were a large number of patients with bloody diarrhoea caused by STEC and an unusually high proportion of these developed haemolytic uremic syndrome (HUS).
A rapid risk assessment A specialised field of applied science that involves reviewing scientific data and studies in order to evaluate risks associated with certain hazards. It involves four steps: hazard identification, hazard characterisation, exposure assessment and risk characterisation. by EFSA and ECDC, published 29 June 2011, highlighted the links between the French and German outbreaks, both associated with sprouts. In both outbreaks the rare strain A subtype of a microbe defined by its genetic make-up; for example, in the case of Escherichia coli O157, the 'O157' part of the name refers to the strain. of E. coli O104:H4 was confirmed. Based on the assessment, fenugreek sprouts were identified as the most likely connection between the French cases and the German outbreak.
What is STEC? How can it be avoided?
All humans and animals carry the bacteria called Escherichia coli (E.coli) in their intestines – they are part of our normal flora and usually harmless. However, there are certain types of E. coli strains that are a risk to human health including those that are capable of producing toxins. These strains are called STEC/VTEC (shiga toxin or verotoxin-producing E. coli) or EHEC (enterohaemorrhagic E. coli), and their toxins have the potential to cause bloody diarrhoea and Haemolytic Uremic Syndrome (HUS), a serious complication that can be fatal. In the EU and as reflected in EFSA’s work on zoonoses, Shiga-toxin producing Escherichia coli is referred to as VTEC (verotoxin-producing E. coli) but the term STEC was used for this outbreak as it is in line with terminology used by WHO and other organisations.
Transmission of STEC infection mainly occurs through eating or handling contaminated food and contact with infected animals. Food can also be contaminated from infected humans handling it. Further person-to-person transmission is possible among close contacts (families, childcare centres, nursing homes, etc).
Together with the ECDC, EFSA published public health advice related to general food hygiene practices and related to the most likely source of the outbreaks. Based on their assessments carried out at the time of the outbreaks in Germany and France, EFSA and ECDC strongly recommended advising consumers not to grow sprouts for their own consumption and also not to eat sprouts or sprouted seeds unless they had been cooked thoroughly (i.e. cooked until steaming hot throughout, not just warm).
On 3 October 2011, EFSA updated its advice to consumers and withdrew its initial recommendations following the removal from the market in all Member States of the most likely source of the contaminated food – a specific lot of fenugreek seeds from Egypt – coupled with on-going import restrictions. EFSA recommends that consumers refer to national food safety agencies for any specific advice regarding sprout consumption.
Milestones
EFSA’s scientific work regarding the STEC outbreak has to date included:
2011
October
A scientific report from EFSA containing a comprehensive overview of what happened from a food safety perspective during the outbreaks of Shiga toxin-producing E.coli (STEC) 0104:H4 2011 in Germany and France.
July
The final report from the EFSA Task Force on Tracing seeds, in particular fenugreek (Trigonella foenum-graecum) seeds, in relation to the Shiga toxin-producing E. coli (STEC) O104:H4 2011 outbreaks in Germany and France.
June
- A joint rapid risk assessment of the HUS outbreak in France focusing on four key areas: food source identification, collaborative trace-back investigations (coordinated by the EFSA Task Force), awareness-raising amongst clinical practitioners and public health advice.
- Joint EFSA/ECDC public health advice on prevention of diarrhoeal illness with special focus on STEC, also called VTEC or EHEC.
- A fast track risk assessment on consumer exposure Concentration or amount of a particular substance that is taken in by an individual, population or ecosystem in a specific frequency over a certain amount of time. to STEC/VTEC through the consumption of raw vegetables and advice on options to mitigate the risks of possible food contamination and human infection.
- A joint technical report with ECDC on the prevalence The proportion of a population found to have a condition. and incidence The number of new events occurring within a specified time period within a defined geographical area; for example, the number of flu cases per year in Europe. of STEC in humans, food and animals based on data supplied by EU Member States annually and data from this outbreak investigation.
EFSA's role
As part of its remit and at the request of the European Commission (EC), EFSA was closely involved in the scientific work related to the outbreaks in Germany and France. The work was carried out in close cooperation with officials and experts from the European Commission, ECDC, relevant EU Member States, the World Health Organization (WHO) and the Food and Agriculture Organization (FAO).
On 27 June, EFSA set up a task force to coordinate investigations to track down the source of any contaminated sprouted seeds in the EU. The task force sought to understand how the production and distribution chain of seeds, bean sprouts and other sprouted seeds are organised throughout the EU. Such scientific cooperation proved useful in investigating the German outbreak.