Investigators who are trying to track down the source of E. coli contamination in romaine lettuce are feeling that they've seen this movie before.
Over the past six weeks, at least 50 people in the U.S. and Canada have gone to the doctor suffering from the symptoms of food poisoning. They were infected with an identical strain of E. coli bacteria. Most of them remembered eating romaine lettuce.
So on Tuesday, the Centers for Disease Control and Prevention issued a warning: Throw away your romaine lettuce. Hearts of romaine disappeared from supermarket shelves. So did bags of Caesar salad mix.
One detail in that announcement really caught the attention of food safety experts. This exact strain of E. coli O157:H7 has been seen before. Just under a year ago, it caused a relatively small wave of illness in the U.S. and Canada, then seemed to disappear. The outbreak got more attention in Canada than the U.S. The Canadians thought people were getting infected from romaine lettuce; the U.S. government wasn't convinced.
Now that strain of bacteria is back. Jeff Farber, at the University of Guelph, in Canada, says this almost never happens. "We usually do not see that; to have, a year apart, the same strain of E. coli O157 still hanging around," he says.
It's disturbing, he says, to realize that the source of that E. coli contamination never was eliminated. "It means that they've never really solved the problem of where the E. coli strain is coming from," he says. But he is optimistic that investigators will find the source this time. "I think it's very important that they do isolate it, so that there's not a third outbreak, because then I think there would be a lot of pressure on public health and the industry to do something drastic," he says.
Farber wouldn't speculate about what that "something drastic" might be.
Lawrence Goodridge, the director of the food safety program at McGill University, in Montreal, says that yesterday's announcement was actually more drastic than usual. The advice to stop eating all romaine lettuce helps protect the public, but it also inflicts a lot of economic damage on workers and companies that actually are selling healthy, uncontaminated lettuce. "There's this fine line that has to be walked by public health officials," he says.
Even though the number of reported illnesses is small — just 50 people so far, out of a total population of hundreds of millions — he's advising people to follow the recommendations from public health authorities. For every case that gets reported, because it was bad enough to send people to the doctor, many more people may be getting sick, he says. "I like to say that certainly, there's no need for the public to panic, but even one case is too much," he says.
He's playing it safe, he says. No romaine on the menu.