Germany’s health minister Ilse Aigner has said she is “really concerned” about a poisoning outbreak that is suspected of having killed three people.
Health officials say 138 people have been infected with a dangerous strain of the E.coli bacterium known as EHEC.
There are other suspected cases, mostly in northern Germany, particularly affecting young women.
One official at a public health institute investigating the outbreak, called the statistics “scarily high”.
A leading international caterer, Sodexo, has confirmed that some of its clients have been affected.
“What happened was, employees of a Sodexo client in Frankfurt got ill. It was discovered that the reason for their illness was the EHEC-virus. We reacted by informing the health authorities. We have closed canteens as a precautionary measure,” said Sodexo spokesman Stephan Dürholt.
Reports say two canteens in Frankfurt have been shut down.
The bacterium is transmitted to humans mainly via contaminated food, such as raw or badly cooked meat, milk, and also salads and vegetables.
The German government is advising consumers to peel or wash vegetables before eating them.