New E coli findings put spotlight back on sprouts

Jun 8, 2011 (CIDRAP News) – German health officials investigating a large Escherichia coli outbreak released new findings today that cast more suspicion on bean sprouts, though tests on a cucumber found in a sick family's compost reportedly yielded the outbreak strain.

Gert Hahne, a spokesman for Lower Saxony state's Consumer Protection Ministry, said 18 people who became will with the enterohemorrhagic E coli (EHEC) O104:H4 outbreak strain got sick after eating sprouts from an organic farm that were served in their company cafeteria in Cuxhaven.

The latest findings push the number of illness clusters to seven, which include about 100 people who got sick after eating at four company cafeterias and three restaurants that are known to have received sprouts from the farm.

On Jun 5, health officials in Lower Saxony state tentatively linked bean sprouts grown at an organic farm in the northern part of the country to the massive EHEC outbreak based on initial tests. But more extensive tests conducted so far on samples from the facility haven't turned up the outbreak strain.

Also, Hahne said three women who worked at the farm and helped package the sprouts were sick with diarrhea during the first half of May, and one of the women had a confirmed EHEC infection. He said that a sick worker could have contaminated the sprouts or could have been sickened by the sprouts on the farm.

The spokesman said that, despite the new clues pointing to sprouts, it is possible that the contamination responsible for the outbreak could have come from multiple sources, Der Spiegel reported.

Shortly after Lower Saxony officials announced the latest sprout farm findings, the health ministry in neighboring Saxony Anhalt state said lab tests detected the E coli O104:H4 strain on a piece of cucumber found in the compost bin of a family that was sickened in the outbreak, the Associated Press (AP) reported today. The cucumber had been in the bin for 2 weeks.

In the family of three, the father had experienced diarrhea, the mother had been hospitalized for several days, and the couple's 22-year-old daughter has been hospitalized for 2 weeks with hemolytic uremic syndrome (HUS), a sometimes fatal kidney condition that has struck an unusually high number of patients in the outbreak.

However, a ministry spokesman said it was impossible to determine if the family contaminated the cucumber or if the cucumber was the source of the pathogen. Earlier in the outbreak, investigators wrongly pegged Spanish cucumbers as the source of the outbreak. German authorities are still advising people to avoid eating cucumbers, tomatoes, lettuce, and sprouts.

Craig Hedberg, PhD, a foodborne disease expert at the University of Minnesota, told CIDRAP News that "dumpster diving" isn't an ideal method for identifying the source of a foodborne disease outbreak. "A positive finding in household garbage from a confirmed case may just reflect the presence of the agent in the household, which was already established," he said.

Most of the investigation findings point back to a sprout source, and microbiological testing a month after the fact doesn't change that, Hedberg said. "Negative micro results cannot negate positive epi results. This is an important principle that we cannot state too strongly."

Germany's health minister Daniel Bahr said today that the number of new EHEC infections is declining, but he added that the outbreak is not over, according to the Der Spiegel report. He spoke to reporters at a press conference in Berlin that followed a meeting with health officials.

The European Centre for Disease Prevention and Control (ECDC) in its latest update today said 2,021 EHEC cases have been reported from EU countries, as well as 722 cases of HUS. Twenty-five EU deaths have been linked to the outbreak. The total represents 266 more infections, 48 more HUS cases, and 2 more deaths since yesterday.

Today EU member countries began using a new case definition for HUS, and said totals for France, Sweden, and the Netherlands have undergone minor adjustments to reflect the change, the ECDC said.

The Robert Koch Institute (RKI), the German government's infectious disease body, said today that HUS and EHEC surveillance data and tracking of bloody diarrhea in emergency departments shows an overall decreasing trend in the number of cases. "It is presently uncertain whether this decline is due to changes in dietary consumption of cucumbers, tomatoes, and lettuce or to the waning of the source of infection," RKI said in a statement posted on its Web site.

It said an earlier case-control study questioned patients about sprout consumption, but only a small proportion said they had eaten them. However, the RKI said its investigators are conducting a third study to further tease out the consumption of salad ingredients, including sprouts, as well as other risk factors.

See also:

Jun 8 Der Spiegel story

Jun 8 AP story

Jun 8 ECDC update

Jun 8 ECDC background on new HUS case definition

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