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Sixteen people in Germany have died so far after consuming a toxic strain of Escherichia coli, traced to . More deaths are expected: of the 1200 people infected so far, most of whom are women, 373 have developed a syndrome of symptoms that includes kidney failure, which can be lethal.

E. coli are normal gut bacteria, but strains called STEC carry genes for a toxin that damages capillaries in the gut, causing bloody diarrhoea. It also activates the clotting system, blocking capillaries and damaging organs.

STEC is carried by cattle, which are immune to the toxin. Victims of the most common STEC strain are usually children who get it from beef or water contaminated by cattle faeces. The strain is rare, and it is not clear if it travels in the same way. But the European Centre for Disease Prevention and Control in Stockholm that eight human infections with the German strain of E. coli have been reported in the European Union since 2008, while Germany and Austria have found it in monitoring samples from food and livestock.

If it does travel in cattle faeces, its presence on organic vegetables is not surprising: more manure is used to fertilise organic than other crops. Whether this poses a threat to health is highly controversial, but have found higher levels of E. coli on organic vegetables. In 2006 an outbreak of STEC on an farm in California killed three people.

“If cattle manure is used as a fertiliser, it is probable that vegetables such as cucumbers will be contaminated with

E. coli,” says Jonathan Fletcher, a microbiologist at the University of Bradford, UK. “If not washed properly it would be present in sufficient numbers to cause infection,” Fletcher adds.