The cucumber that didn't do it: inside Europe's deadliest E. coli outbreak

In May 2011, northern Germany became the epicenter of the deadliest E. coli outbreak ever recorded. A rare strain — O104:H4 — sickened nearly 4,000 people and killed 53, most of them in Germany. More than 800 victims developed hemolytic uremic syndrome, the kidney-shutting complication that made this outbreak uniquely terrifying. Germany normally sees a dozen or so HUS cases a year.

In the first frantic weeks, nobody knew the source, and the vacuum filled with a false accusation. German authorities pointed at cucumbers imported from Spain after early tests in Hamburg. European shoppers swore off Spanish produce overnight, costing Spanish exporters an estimated $200 million a week. Spain threatened legal action. Further testing showed the Spanish cucumbers carried E. coli, but not the outbreak strain — they were exonerated, and officials were left warning Germans off all raw cucumbers, tomatoes, and lettuce while admitting they might never find the real source.

The trail eventually led somewhere nobody had looked: sprouts. An organic farm in Bienenbüttel, Lower Saxony, was identified as the distribution point, and on June 30 Germany's Federal Institute for Risk Assessment announced the likely origin — organic fenugreek seeds imported from Egypt, used by the farm and by home sprouters alike. The seeds had carried the pathogen; sprouting them in warm, wet conditions had multiplied it. Where and how the seeds were contaminated was never determined.

The episode left a trail of collateral damage beyond the victims. Russia banned all fresh vegetable imports from the EU for most of June. German farmers lost tens of millions of euros to the raw-vegetable warning. And Spain's produce industry learned how quickly a preliminary lab result, announced before the science is done, can devastate an innocent party.

The Robert Koch Institute declared the outbreak over on July 26, 2011. It remains the largest HUS outbreak ever described — and a case study in why, during a food scare, the first suspect named is not always the one that did it.