Imported fenugreek seeds from Egypt may be the source of highly toxic E.coli outbreaks in Germany and France that have killed at least 48 people, according to initial investigations by European scientists.
More than 4,000 people across Europe and in North America have been infected in the deadliest outbreak of E.coli so far recorded, which started in early May. Almost all of those sickened lived in Germany or had recently travelled there.
The German outbreak and a smaller cluster of E.coli centred around the French city of Bordeaux have both been linked to sprouted seeds.
Experts from the European Centre for Disease Prevention and Control (ECDC) and the European Food Safety Authority said initial investigations suggested that "the consumption of sprouts is the suspected vehicle of infection in both the French cluster and the German outbreak.
"The tracing back is progressing and has thus far shown that fenugreek seeds imported from Egypt either in 2009 and/or 2010 are implicated in both outbreaks," they said in a joint statement posted on the ECDC's website late on Wednesday.
The European investigators said that since contamination of the seeds could have occurred at any stage in the long and complex supply chain between seed production, transport, packaging and distribution, "this would also mean that other batches of potentially contaminated seeds are still available within the EU (European Union), and perhaps outside".
The strain of E.coli infections in the current outbreaks - known as STEC O104:H4 - can cause serious diarrhoea and, in severe cases, kidney failure and death.
The ECDC and EFSA said a batch of fenugreek seeds imported from Egypt in 2009 appeared to be implicated in the outbreak in France, and a 2010 batch was "considered to be implicated in the German outbreak".
But they said there was still "much uncertainty" about whether these seeds from Egypt were "truly the common cause of all the infections" as there are currently no positive bacteriological results.
"Until the investigation has been finalised, ECDC and EFSA strongly recommend advising consumers not to grow sprouts for their own consumption and not to eat sprouts or sprouted seeds unless they have been cooked thoroughly," they said.
E.coli bacteria thrive in nutrient-rich environments like the guts of humans or cows. The STEC O104:H4 strain has been found to be particularly sticky, making it likely to be able to cling on to leaves, seeds and other foodstuffs.
Fenugreek is used as a herb, a spice in many types of curry, and for spouting seeds used in salads, and as a garnish.