Do you remember what was in the salad you ordered a week ago at a restaurant? In a just published paper in the New England Journal of Medicine, researchers from Germany’s Robert Koch Institute write that, when tracing an outbreak like the E. coli one last summer in northern Germany that sickened more than 4,300 people and killed 55, scientists and public health officials can never unestimate how many food items people will forget they ate.
In the case of the outbreak that started around the city of Hamburg last summer, scientists were eventually able to trace the culprit to be fenugreek sprouts grown from tainted fenugreek seeds from Egypt, but only after months of uncertainty. An initial claim implicating cucumbers from Spain led to an angry outcry from that country. As time passed, German health authorities continued to offer contradictory information about the source of the outbreak, also singling out tomatoes and leaf salads in local restaurants:
Early studies in Hamburg suggested that infections were probably community-acquired and were not related to food consumption in a particular restaurant. A first case–control study that was conducted on May 23 and 24 suggested that raw food items, such as tomatoes, cucumbers, or leaf salad, were the source of infection. The consumption of sprouts, which was previously implicated in outbreaks of Shiga-toxin–producing E. coli in the United States and Japan, was mentioned by only 25% of case subjects in exploratory interviews, so consumption of sprouts was not tested analytically. [my emphasis]
So the researchers kept looking, tracing salad ingredients both forward — from distributors to restaurants to consumers — and backwards, to the farmers. But one of the hardest parts was getting people to remember what exactly had been in their salads. (Even meals that are supposed to be memorable can fade surprisingly quickly, as April Fulton reported this year.)
“The one dish that frequently exposed guests to sprouts was the side salad, which contained tomatoes, cucumbers, three sorts of leaf salads and sprouts,” the researchers write in NEJM. “Sprouts may have been the ingredient that visitors recalled least in such a mixed salad.”
It’s an interesting finding, given that we hear a lot about how the long road from farm to fork — with food products zigzagging the globe at greater and greater distances — puts us at risk.
A salad in Germany or in the US could have ingredients stemming from several different countries, that have passed through several different ports of call. Indeed, while the tainted fenugreek seeds originated in Egypt, the contaminated sprouts came from a local farm in Germany.
If you’ve had a salad in a restaurant, or a ready-made one purchased from a local store, do you remember everything besides the main ingredients — seeds, spices in the dressing, types of greens — that was in it? Did you even think to check before purchasing it, let alone eating it?
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