On the 21st of May 2011, Germany reported an ongoing outbreak of Shiga-toxin producing Escherichia coli- bacteria (STEC), serotype O104:H4 (Frank et al., 2011). In Germany, between the 1st of May and the 28th of June 2011, 838 Haemolytic Uremic Syndrome (HUS) cases and 3 091 STEC cases with diarrhea have been reported, of which 47 persons have died (RKI, 2011).
On Friday the 24th of June, France reported a cluster of patients with bloody diarrhoea, after having participated in an event in the Commune of Bègles near Bordeaux on the 8th of June. As of 28 June, eight cases of bloody diarrhoea and a further eight cases with HUS have been identified. Eleven of these patients, seven women and four men, between 31 and 64 years of age, had attended the same event in Bègles. Infection with E. coli O104:H4 has been confirmed for four patients with HUS.
Six of the cases reported having eaten sprouts at the event on the 8th of June, and leftovers are being analysed. Outbreak investigation revealed that the suspected sprouts of fenugreek, rocket and mustard had been privately produced in small quantities by the organiser of the event from seeds bought at an approved garden centre, and were not imported from the sprout producer implicated in the outbreak in Germany (INVS, 2011). An analytical epidemiological study is ongoing with the persons that attended the event on 8th of June. Local trace back investigations in France suggested that the seeds for sprouting were distributed to the approved garden centre by a UK based company.
EFSA was urgently requested by the Commission to initiate a comprehensive tracing back exercise (followed by tracing forward) to identify the source of the two outbreaks and contribute to identifying appropriate risk mitigating measures regarding potential further outbreaks. These further investigations particularly aimed at determining whether the origin of the suspected sprout-seeds from the French cluster were linked to the large outbreak in northern Germany. This report documents the steps taken in the trace back process. Any activities already undertaken by the Task Force with regard to tracing forward are also described.
A trace back investigation is the method used to determine and document the distribution and production chain, and the source(s) of a product that has been implicated in a food-borne illness investigation. A trace forward investigation aims to find the distribution of the suspected food products along the food chain from the origin in the direction of the consumer.
Using this approach for this investigation, at each step of the delivery/production chain identified in the trace back, further investigation was initiated to try and account for all seeds in any suspect lots. The objective was to identify critical lots and their current location. To this end, detailed information on each lot of seeds was established for each step of the delivery/production chain back to the importation into the EU.
The comparison of the back tracing information from the French and German outbreaks leads to the conclusion that lot # 48088 of fenugreek seeds imported by the Importer, from Egypt, is the most likely common link, although it cannot be excluded that other lots may be implicated.
Given the possible severe health impact of exposure to a small quantity of contaminated material, and, in the absence of information regarding the source and means of contamination and possible cross-contamination, it seems appropriate to consider all lots of fenugreek from the identified exporter as suspect. In this regard, the thus far negative test results from the microbiological tests carried out on seeds cannot be interpreted as proof that a batch is not contaminated with STEC O104:H4 since these results depend on and may be limited by both the analytical and diagnostic performance characteristics as well as by the nature of the sampling plan.
The number of Member States that have received parts of the suspected lots is much larger than previously known and it cannot be excluded that other Member States and third countries were supplied. The trace forward operation is becoming complex and widespread and may take weeks.
This report is one of many elements contributing to the investigation of the cause of this outbreak, and should not be considered in isolation. The findings of this study are consistent with other investigations conducted thus far. Specifically, it supports the hypothesis that the outbreaks in Germany and France are linked, and are due to the import of fenugreek seeds, which became contaminated with STEC O104:H4 at some point prior to leaving the Importer. The contamination of seeds with the STEC O104:H4 strain reflects a production or distribution process which allowed contamination with faecal material of human and/or animal origin. Where exactly this took place is still an open question. Typically such contamination could occur during production at the farm level. While contamination at subsequent steps in, up to, and including at the Importer can not be excluded, it is highly unlikely that contamination could have taken place during transport of the sealed container.
The following several recommendations are made. In the short term, all efforts have to be made to prevent any further exposure of the consumer to seeds from the lots of concern. As a consequence, it seems important that a trace back investigation be initiated on the incriminated lots of fenugreek seeds in the third country from which they were exported to the EU. In addition, it appears essential that Member States and third countries initiate or complete forward tracing of companies receiving the suspect lots. In the medium term, and using the experience of the back tracing of sprout seeds in Europe, appropriate tools for the generic methodology of trace back should be developed and validated at the EU level.
 European Food Safety Authority; Urgent advice on the public health risk of Shiga-toxin producing Escherichia coli in fresh vegetables. EFSA Journal 2011; 9(6):2274. [50 pp.]
 In the EU and as reflected in EFSA’s work on zoonoses, Shiga-toxin producing Escherichia coli-bacteria is referred to as VTEC (verotoxin-producing E. coli) but the term STEC is used for this outbreak as it is in line with terminology used by WHO and other organisations.
 RASFF Alert Notification 2011.0842