Experts working to find out what has caused serious food poisoning, which has killed 22 people, think they have found the source of the bug.
They think the illness has come from a farm in north Germany which produces bean sprouts.
The farm has been closed and people in Germany told to stop eating bean sprouts while tests are carried out.
More than 2,150 people in Germany have become ill. Scientists say the illness looks like a new disease.
People in 12 other countries, including the UK, have also become ill after travelling to Germany.
Doctor explains E. coli
The bean sprouts that are thought to be the cause include adzuki, alfalfa, broccoli, peas, lentils and mung beans, all grown in the farm's nursery.
Twenty-one of the victims have died in Germany, and one person in Sweden.
Experts say E. coli is not that common and most kids come through it all right, although some may need special treatment.