Crudites eaten at a children’s center in the French city of Bordeaux are helping doctors in their two- month hunt for the source of the world’s deadliest E. coli outbreak.
The bacterium that began sickening thousands of people in Germany in early May is the same as one that gave more than a dozen people bloody diarrhea and kidney failure in southern France last month, a study released on June 30 found. After tracing common food sources, epidemiologists found fenugreek seeds from Egypt could be implicated in both outbreaks, authorities said.
Scientists are checking bacterial specimens to confirm the link and solve a mystery hanging over the outbreak, which caused illness in 4,125 people and killed 49 in 13 European countries.
“The one common source here that keeps coming up over and over again is Egyptian seeds,” Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, said in an interview yesterday. “Fenugreek is showing up clearly in the French outbreak and showing up clearly in the German outbreak.”
The link to fenugreek, a clover-like plant used as both an herb and a spice, was identified after disease investigators found it was served at an event attended by patients in the Bordeaux suburb of Begles.
Eleven of the French cases had attended an open day at a children’s community center on June 8, according to a June 30 report in Eurosurveillance, a weekly online journal on infectious diseases published by the European Centre for Disease Prevention and Control in Stockholm.
A cold buffet was served consisting of crudites, or raw vegetables, three dips, industrially produced gazpacho, a choice of two cold soups, pasteurized fruit juices and individual dishes composed of white grapes, tomatoes, sesame seeds, chives, industrially produced soft cheese and fruit, the report said.
The soups were served with fenugreek sprouts, a small amount of which were also placed on the crudite dishes. Mustard and rocket sprouts, still growing on cotton wool, were used to decorate the dishes, the authors said.
The sprouts had been grown from rocket, mustard and fenugreek seeds planted at the center the previous week. The seeds were bought from a branch of a national chain of gardening retailers, having been supplied by a distributor in the U.K., the authors said.
Leftover mustard and rocket seeds, gazpacho and tap water samples from the community center have been sent for microbiological analysis, as have samples of rocket, mustard, fenugreek and other seeds from the French gardening retailer. Preliminary results are being analyzed, the researchers said.
Microbiological testing won’t always find the pathogen, especially if the contamination is sporadic and at low levels, Osterholm at the University of Minnesota said.
“Absence of this in a product doesn’t mean anything about what product’s involved,” he said. “Even if 1-to-2 percent of the seeds are contaminated, it still means that potentially many thousands, if not millions, of people have been exposed given the wide distribution of those seeds and how much of this is consumed.”
The U.K. Food Standards Agency is testing samples of three varieties of seeds sold by Thompson & Morgan (UK) Ltd.: fenugreek, white mustard and rocket. The tests are part of a probe into the French outbreak, the 156-year-old company, based in Ipswich, England, said in an e-mail June 30.
Withdrawn From Sale
Although there has been no established link, Thompson & Morgan has temporarily withdrawn from sale five sprout-seed varieties, including fenugreek, according to a statement on its website. The company’s own supplier sourced the Egyptian seed, and this sprouting seed was then exclusively supplied into the French garden center market, according to the e-mail.
About 9,451 people were sickened and 12 killed in a series of E. coli outbreaks in Japan between May and December 1996, according to a 1999 study in the American Journal of Epidemiology. The majority of those cases were acquired by tainted radish sprouts in school lunches.
Radish seeds experimentally infected with the germ produced contaminated sprouts, suggesting the original source may not be the farm supplying the produce, researchers in Tokyo reported in a 1998 study.
The European agencies advised consumers not to grow sprouts for their own use or to eat sprouts or sprouted seeds unless they have been thoroughly cooked. Seed imported from Egypt in 2009 appears to be implicated in the outbreak in France, while the German outbreak has been associated with seed imported last year, the ECDC said in a June 29 statement.
Even if the link with Egyptian seeds is confirmed, it won’t explain the most recent case in Sweden, the ECDC said. So far, no consumption of sprouts has been implicated in the case, which is still being investigated, the agency said.
The current E. coli epidemic is more deadly than previous outbreaks because the pathogen produces a poisonous byproduct called Shiga toxin and has the ability to stack together and stick to the gut, according to a study led by Helge Karch, director of the Hygiene Institute at the University of Muenster, last month. The unusual combination of traits makes it more likely for infected people to develop a potentially fatal kidney complication called hemolytic uremic syndrome, or HUS, they said.
The same type of E. coli, called O104, sickened a patient in South Korea in 2004. Genetic studies of that bacterium showed it’s unrelated to the pathogen in Europe, scientists at the National Institute of Health in Chungcheongbuk-do said in a letter in the July edition of Emerging Infectious Diseases journal.
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