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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A closeup view of the bacterium behind the foodborne disease outbreak centered in Germany. Manfred Rohde/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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Lettuce at an organic vegetable farm in Teltow, Germany. Organic farmers in Germany are reporting a surge in demand for lettuce and cucumbers in the wake of an outbreak of E. coli after health officials warned people not to eat cucumbers, lettuce and tomatoes, though organic produce may not necessarily be safer. Sean Gallup/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

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