A-ha! It was the sprouts after all.
Even though tests from an organic farm in Northern Germany failed to detect the Escherichia coli strain that has sickened more than 3,000 and killed 31, German disease gumshoes concluded from the pattern of cases that sprouts are to blame.
"It is the sprouts," Reinhard Burger, head of Germany's Robert Koch Institute, said Friday at a media briefing. How does he know? The institute, along with two other government groups, linked clusters of illness to 26 restaurants and cafeterias that got sprouts from the same grower in the German state of Lower Saxony, the Associated Press reports.
German officials lifted warnings against the consumption of cucumbers, lettuce and tomatoes as a result of the finding. It's possible that by now all the tainted sprouts have been eaten or discarded. The farm that was suspected as the E. coli source was shut down more than a week ago. Even so, the government continued to warn people not to eat sprouts.
As the outbreak widened, German health authorities were criticized for issuing contradictory information — such as an early warning against Spanish cucumbers that officials in that country disputed — and for being too slow to reach a conclusion about the cause.
On Wednesday's All Things Considered, Dr. David Acheson, formerly of the Food and Drug Administration, suggested German investigators were too hung up on finding a smoking gun — a food sample testing positive for the particular strain of germ isolated from sick people.
"This far out in the outbreak that could be almost impossible to find," Acheson told host Michele Norris, "because the food has either been consumed or spoiled and has been thrown away."
In many U.S. investigations, he explained, authorities relied on "solid epidemiology without actually having a positive sample, like spinach in 2006 which was obviously a massive E. coli outbreak. And it was very evident from the epidemiology that it was spinach."
The problem with looking for a positive test from samples is that "the further you are away from the start of the outbreak the harder it's going to be to do that, and so you continue to struggle," he said.
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MELISSA BLOCK, host:
German health authorities say they think they have identified the cause of the E. coli outbreak. It's made 3,000 people sick and killed at least 30. NPR's Richard Knox tells us more.
RICHARD KNOX: Dr. Reinhard Burger of the German disease control center says it hasn't been possible to pin down the source of the outbreak. But at a press conference today in Berlin, he says there's one strong possibility.
Dr. REINHARD BURGER: (Speaking foreign language).
KNOX: They've narrowed it down to sprouts, he says. But they haven't been able to detect E. coli on any food samples. It's just that people who ate raw sprouts were more likely to get sick than those who didn't, nine times more likely.
Dr. Thomas Frieden, head of the U.S. Centers for Disease Control and Prevention, says this doesn't constitute scientific proof.
Dr. THOMAS FRIEDEN (Centers for Disease Control and Prevention): The smoking gun is when you can find from the people who are sick the specific strain, find from the source the specific strain and then do sophisticated DNA testing to prove that they are identical.
KNOX: Still, Frieden thinks the Germans may be right this time.
Dr. FRIEDEN: We'll have to see what the evidence shows, but all of the information they're reporting suggests that it's the likely cause.
KNOX: One reason is that sprouts are notorious disease carriers. They've caused nearly three-dozen outbreaks of food-borne illness in this country since 1996. That's because bacteria often get inside sprout seeds. Then the seeds are grown in warm, moist conditions that are ideal for multiplying the germs. Frieden no longer thinks of raw sprouts as health food.
Dr. FRIEDEN: I'll tell you, when I was living in India, I brought sprouts from the U.S. - this is 15 years ago, before we understood how much of a challenge they could be to keep sterile - and when I got ill and couldn't identify the source, I realized it was probably actually inside the seed that I had imported into India from the U.S.
KNOX: He doesn't eat them now, and the CDC advises against raw sprouts for pregnant women, elderly people, young children and anyone with a weakened immune system.
Richard Knox, NPR News. Transcript provided by NPR, Copyright NPR.