Germans have been warned not to eat cucumbers until tests identify the source of a deadly E.coli outbreak that has killed 10 and spread across Europe.It is thought contaminated organic cucumbers were imported from Spain, but further tests are being carried out.The vegetables have left hundreds ill with Hemolytic-uremic Syndrome (HUS), which causes kidney problems.Cases have also been recorded in Sweden, Denmark, the Netherlands and the UK.One woman was taken to hospital in Poland on Monday and said to be in a serious condition after returning from a trip to the northern German city of Hamburg, where more than 450 cases have been reported.On Sunday, authorities in the Czech Republic and Austria took some Spanish-grown cucumbers off shop shelves amid contamination fears.Czech officials said affected cucumbers may also have been exported to Hungary and Luxembourg.Suspicion has fallen on organic cucumbers from Spain imported by Germany but then re-exported to other European countries, or exported directly by Spain.Two Spanish greenhouses identified as sources for the outbreak have been closed and are currently under investigation to see whether the outbreak originated there or elsewhere, said an EU spokesman.HUS often occurs after a gastrointestinal infection with E.coli.Contagious cucumbers?The Sweden-based European Centre for Disease Prevention and Control has called the outbreak "one of the largest described of HUS worldwide and the largest ever reported in Germany".It has baffled scientists because whereas HUS normally affects children under the age of five, in this outbreaks nearly 90% are adults and two-thirds are women, says the BBC's Stephen Evans in Berlin.One possibility is that they became infected after eating food for what they thought were health reasons, adds our correspondent.The DNA of the bacterium is to be analysed later to try to find ways of catching it early in people infected by it.The sickness is not directly contagious but it can be transferred between people if an infected person prepares food for others.The German authorities warn that the source may still be active and that means there is a possibility of the outbreak getting worse.Source: BBC