Staff of Berlin's Robert-Koch-institute wear protective gear as they investigate an organic farm that had been identified as a possible source of the deadly outbreak of E.Coli in the village of Bienenbuettel some 300 km north west of Berlin on June 6, 2011. The source of the killer bacteria remained elusive on June 6 after Germany announced that initial tests on suspected organic sprouts had proved negative and the outbreak's death toll grew to 23. Some 2,000 people have become ill across Europe from the enterohaemorrhagic E. coli (EHEC) outbreak which has affected 12 countries. AFP PHOTO / ODD ANDERSEN