Reinhard Burger, president of the Robert Koch Institute, tells reporters in Berlin Friday that sprouts from a German farm are the cause of the country's massive foodborne illness outbreak. Michele Tantussi/AP hide caption

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President Obama and Chancellor Angela Merkel during the official arrival ceremony for the German leader at the White House this morning (June 7, 2011). Jewel Samad /AFP/Getty Images hide caption

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Greenhouses of the shuttered Gaertnerhof Bienenbuettel organic farm in Bienenbuettel, Germany. Health authorities in the German state of Lower Saxony closed the farm over worries that the vegetable sprouts grown there could be a source of E. coli outbreak that has infected more than 2,300 people. But preliminary tests came back negative. Joern Pollex/Getty Images hide caption

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A farmer holds cucumbers in a field in Malaga, Spain. Cucumbers from Spain have been eyed as the source of a disease outbreak in Germany. Jorge Guerrero/AFP/Getty Images hide caption

itoggle caption Jorge Guerrero/AFP/Getty Images