German E. coli outbreak: Closer look at bacterium’s new strain

Listeria-contaminated cantaloupeshaven’t been the only troublesome produce in the news in 2011. Back in the spring and early summer, more than 4,000 people were sickened after eating fenugreek sprouts that were contaminated with Escherichia coli. The unusual outbreak, which was centered in Germany, caused digestive distress and kidney problems, ultimately killing 50 people in 15 countries.

Two studies and an editorial, published online Wednesday by the New England Journal of Medicine, sum up what health authorities have figured out about the foodborne illness so far:

• The outbreak began in May 2011 and was declared to be over on July 26.
• A new strain of the E. colibacterium, dubbed O104:H4, followed an unusual pattern: It mostly affected adults of all ages, rather than young children and the elderly. It had a longer incubation period than usual -- 8 days, versus 3-4 days -- and an unusually high number of the people who became ill, 22%, developed hemolytic-uremic syndrome, a condition in which the kidneys are damaged by toxins produced by gastrointestinal infections. The unusual age distribution could have reflected the possibility that older people eat more sprouts, or it may be a characteristic of the new strain.
• Hemolytic-uremic syndrome was also more common in women than in men, perhaps because women eat more sprouts than men.
• Using a variety of methods to trace where the E. colibacteria got into the food chain, researchers determined that the contamination began in Egypt, where either human or animal feces came in contact with fenugreek seeds during storage or transportation. The seeds were exported to Europe. People got sick from eating the fenugreek sprouts.
• Initially, health authorities had thought other raw foods were behind the outbreak, including tomatoes, cucumbers and leaf salad; E. coli sufferers hadn’t mentioned sprouts in early interviews about what they had eaten. The confusion was explained when the researchers, examining restaurants’ involvement in the outbreak, looked at a side salad that had all of those veggies -- and sprouts -- mixed together, and eventually linked the sprouts to the bacteria. “Sprouts may have been the ingredient that visitors recalled least in such a mixed salad,” the study explained.

In an accompanying editorial, Dr. Martin J. Blaser of New York UniversityLangone Medical Center struck a cautionary tone. “This O104:H4 strain was well armed for mayhem and reminds us that evolution is a constant,” he wrote. He called on public health authorities to adopt new rules that would allow researchers to conduct immediate clinical trials the next time there is a large outbreak.

“Patients should be randomly assigned to various clinically suitable regimens to learn what works and what does not,” he wrote, “so we can learn while trying to mitigate these tragedies.”

In the last couple of months, the Los Angeles Times has been following the cantaloupes-listeria outbreak. Return to the Booster Shots blog to read more about it.