EHEC Outbreak 2011
From May to July 2011 there were many occurrences of illness in Germany with hemolytic-uremic syndrome (HUS) and bloody diarrhoea linked to an infection with enterohemorrhagic Escherichia coli (EHEC) of the serotype O104:H4. The outbreak affected all federal laender, but mainly those in northern Germany.
According to information provided by the Robert Koch Institute, almost 4,000 people were infected with EHEC during the outbreak in 2011 and 53 of them died as a result. This makes it the largest outbreak of disease through EHEC infections in Germany to date and, as far as the number of HUS cases is concerned, the largest outbreak of this kind ever described anywhere in the world. Even though it was not possible to produce microbiological evidence, fenugreek seed imported from Egypt and used to producing sprouts and shoots in a horticultural farm in Lower Saxony as well as by private persons are regarded as the cause of the EHEC outbreak in 2011. Where and how the seeds came into contact with the pathogen that caused the outbreak could not be determined, however.
Investigation into the EHEC Outbreak 2011
The BfR has given its comprehensive support to the epidemiological and microbiological outbreak investigations conducted by the federal and laender authorities.
By evaluating and comparing the delivery lists and distribution channels of consumed foods from 41 well-characterized outbreak clusters, it was possible to establish a connection to sprouts and shoots delivered from a horticultural farm in Lower Saxony. After infections with EHEC O104:H4 also occurred in France in June 2011, it was possible to further restrict the suspect food “sprouts”. The persons who were taken ill near Bordeaux had eaten sprouts that were produced in a French children’s hostel from three different seed varieties. Only fenugreek sprouts were contained in the sprout mixture consumed in France as well as the sprout mixtures in the horticultural farm in Lower Saxony associated with the outbreak clusters examined in Germany. In addition to this, cases of illness also occurred in Germany within the scope of the 2011 EHEC outbreak after the consumption of sprouts self-cultivated from fenugreek seeds of the same batch.
Further investigations on EU level have shown that a fenugreek seed batch produced in Egypt as far back as the winter of 2008/2009 is the only connection between the outbreaks of illness in Germany and France. Partial quantities of this fenugreek seed batch were used for sprout production in the horticultural farm in Lower Saxony, as well as the hostel in France. For the protection of consumers, the European Commission then ordered the recall and safe disposal of certain fenugreek seed batches from Egypt and imposed an import ban on fenugreek seeds and other plant-based foods from Egypt for a limited time period.
The risk of consumers contracting an EHEC infection after consuming raw sprouts produced from fenugreek seeds was considerably reduced through the recall and import ban, thus helping to contain the EHEC outbreak in 2011.
Recommendations for the consumption of sprouts and shoots
Fenugreek seeds purchased before October 2011 which are still in storage in private households should not be allowed to sprout under any circumstances. They should be disposed of precautionary along with the household refuse. Anyone who still wishes to eat them should only do so once they have been prepared as hot foods.
It is known from the investigation into previous outbreaks that the consumption of raw sprouts can lead to diseases such as salmonellosis. The reason for this is that the seeds used can already be contaminated with pathogens and that the cultivation conditions for sprouts and shoots (warmth and moisture) then favour the propagation of these pathogens.
Thorough washing of the sprouts is not sufficient to safely eliminate the pathogens, but they can be killed off by boiling or frying the sprouts. For this reason, it is recommended by way of precaution that people whose immune system is weakened or not fully developed (young children, pregnant women, old and sick people) only eat sprouts and shoots after they have been sufficiently heated.
BfR Risk Assessment of the EHEC Outbreak 2011
The BfR has evaluated the results of the outbreak investigation in three risk assessments and published them in the internet in the form of statements and press releases on the EHEC Outbreak 2011.