Today, researchers at the Robert Koch Institute (RKI), the German center for disease prevention and control, confirmed the suspicion in what they call a “recipe-based restaurant cohort study.” “The problem is that many people do not remember exactly what was in the food they had for lunch or dinner days ago,” says Gérard Krause, head of infectious epidemiology at RKI. To address that problem, the researchers identified five travel groups that had eaten at a restaurant in Northern Germany. There were EHEC victims in all five groups; altogether, 19 of the 112 diners had become infected. (The name of the eatery has been kept secret.) On Tuesday and Wednesday, research teams swarmed out to interview the groups' members. Using order lists, bills, and photos, they managed to determine for most of the guests which items on the menu they had chosen. At the same time, three researchers went to the kitchen to find out how exactly the food was prepared and what ingredients went into each dish. “Only by bridging the memory gaps of the guests with the detailed knowledge of the chefs could we find out exactly what every guest had consumed,” says RKI President Reinhard Burger. “Those photos really helped us as well.”
The researchers returned to Berlin on Wednesday evening and started entering the data into their computers. A statistical analysis, ready at 6:00 Thursday morning, revealed that people who had eaten sprouts were 8.6 times more likely to have become infected with EHEC than those with sprout-free meals. All 19 guests who had fallen ill had eaten sprouts. On the strength of this evidence—and because a total of 26 EHEC clusters has been traced back to the sprout farm in Bienenbüttel—the BfR officially exonerated the other vegetables at a press conference here today. Households and restaurants were advised to destroy any sprouts they had in stock and any food that might have come into contact with them.