After vacillating from Spanish cucumbers to Germany sprouts and back to cucumbers, Germany’s outbreak task force has settled on sprouts.

According to information released earlier today (June 10th), epidemiological and traceback studies of disease clusters in five affected provinces point conclusively to bean and/or seed sprouts produced by Gärtnerhoff Bienenbüttel GmbH, an organic grower in Lower Saxony. The official government news release did not name the grower.

Although lab tests have not yet revealed the presence of the outbreak strain in samples of sprouts produced by the grower, all of Gärtnerhoff Bienenbüttel’s produce – including fenugreek, mung bean, lentil, adzuki bean, and alfalfa sprouts – has been recalled, and the grower has suspended operations. Federal and State inspectors are working to determine how the sprouts became contaminated – possibly through the water supply, a human source, or the seeds themselves.

The Germany government has rescinded its warning against consuming raw tomatoes, cucumbers and salad greens.

As of June 9th, Germany has recorded 759 cases of hemolytic uremic syndrome (HUS), with 21 deaths, and 2,229 cases of non-HUS E. coli O104:H4 infections (with 9 deaths), for a total of 2,988 documented illnesses and 30 deaths. Thirteen other European countries, Canada and the USA have reported outbreak-related illnesses, as follows:

  • Austria: 4 cases, including 1 HUS
  • Canada: 1 case
  • Czech Republic: 1 case involving a tourist from the USA who had travelled in Germany
  • Denmark: 20 cases, including 8 HUS
  • France: 2 confirmed cases + 7 cases of bloody diarrhea not yet lab-confirmed
  • Greece: 1 case involving a German tourist
  • Luxembourg: 1 case
  • Netherlands: 8 cases, including 4 HUS
  • Norway: 1 case, involving contact with a German in Norway
  • Poland: 2 cases of HUS
  • Spain: 2 cases, including 1 HUS
  • Sweden: 47 cases, including 17 HUS (one fatal HUS case)
  • Switzerland: 5 cases
  • United Kingdom: 5 cases, including 3 HUS
  • USA: 4 cases, including 3 HUS. One of the HUS cases is confirmed; the other 2 HUS cases and the EHEC case are awaiting lab confirmation.

Including all European and North American cases, there are a total of 3092 reported outbreak cases – 798 HUS and 2,294 non-HUS EHEC. All but 2 of the 3092 outbreak victims either travelled to or lived in Germany during the incubation period for the infection.

Germany explains its delay in identifying sprouts as the source of the second largest – and the most deadly – E. coli outbreak ever recorded as follows (copy-edited* Google translation of relevant portion of the official news release):

A range of animal and vegetable foods, including sprouts, were taken into account during the first intensive survey of of patients from Hamburg (20.5./21.5). In this exploratory survey, only 3 of 12 patients reported having eaten sprouts. The patients who were interviewed were very clear and deliberate about their eating habits; it seemed unlikely that they would have under-reported eating sprouts. It is a methodological requirement and standard practice to include only those possible exposures that are potentially able to explain most of the epidemiological outbreak events. Including a large number of exposures increases the risk of false positive correlations. Therefore, sprouts were not immediately pursued. Sprouts were taken into account in subsequent detailed RKI surveys. In total, 16 (30%) of the 54 patients who were interviewed in-depth reported having consumed sprouts during the assumed infectious period.

An in-depth raw food case-control study, which included 26 HUS patients from Lubeck, Bremerhaven and Bremen, was begun on 05/29/2011 to differentiate more accurately between various vegetable foods. In this study, 6 out of 24 (25%) case-patients reported having sprouts, compared with 7 out of 80 (9%) control patients. The statistical significance of this difference was limited – significant in the unvariate analysis, but not in the multivariable analysis. The consumption of other plant foods – tomato, cucumber or lettuce – could not readily be differentiated, as these vegetables are so often consumed together.

Bottom line – the German investigators took at face value the initial questionnaire responses, instead of probing further to jog the memories of the interviewees.

It’s fortunate that sprouts have a relatively short shelf life. Between the exhaustion of the existing supply, the recall of sprouts from the market, and the suspension of production by Gärtnerhof Bienenbüttel, this outbreak should be on the wane.

Cold comfort to European growers of tomatoes, cucumbers and salad greens.

And very cold comfort to the more than 3,000 outbreak victims and their families, and to the families and friends of the 31 people who died as a result of “healthy” eating habits.

*I took the liberty of editing the Google translation for improved comprehension.