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Marler Blog Providing Commentary on Food Poisoning Outbreaks & Litigation

Chronology of the E. coli O104:H4 Outbreak Investigation – The German EHEC Task Force Final Results

According to the European Centre for Disease Control and Prevention, as of today, the cumulative number of probable and confirmed STEC cases in the EU/EEA is 3,867 (not including six in the United States, including one death). This includes 762 HUS STEC cases and 3,105 non-HUS STEC cases. In total, 44 infected persons have died, of which 28 were HUS STEC cases and 16 were non-HUS STEC cases.

In Germany, since the last update, one HUS STEC case has been excluded, and 20 non-HUS STEC cases have been reported. Within the last 10 days (4 July – 13 July), one HUS STEC case and eight non-HUS STEC cases fell ill. The last known date of illness onset in a patient with confirmed STEC O104 was 7 July 2011. This was also the last reported date of illness onset among all cases.

Note: Suspected cases (Germany: 146 HUS STEC (7 deaths), France: 5 non-HUS STEC) are not included.

Below is a very interesting presentation on the actual investigation of the outbreak that I received this morning.  A couple of things of note: 1) How long it took from the first illness (first week of May) until the investigation got fully underway, and 2) The fact that no food item was never positively identified via test results (either because food already consumed or destroyed, or tests for E. coli O104:H4 on food are not yet advanced enough for detection). 

Like all outbreak investigations, this is a good read and a cautionary tale for Untied States public health officials and policy makers.

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Download – Chronology of the E. coli O104:H4 Outbreak Investigation – The German EHEC Task Force Final Results – (Thanks Albert)

Breaking News – AP reports that German authorities say the farm involved in a deadly E. coli outbreak is being cleared to reopen following thorough testing and the removal of all fenugreek seeds – considered the likely source.  The outbreak was traced in early June to the vegetable sprout farm at Bienenbuettel, south of Hamburg. European authorities later said one batch of fenugreek seeds from Egypt was probably the source of the bacterial outbreak that killed 53 people – 51 in Germany, and one each in Sweden and the U.S.

  • Carol Buente

    I read a long article in Agri News in ILL that only mentions sprouts not what kind, do they really know? I would think this sprout would have a very short life span in a grocery store? I’ve never eaten any so I don’t know. Is it sprayed to make it last longer? My local Kankakee paper has not run anymore stories on it at all. I do enjoy your updates since I am at home and not out in the working public any longer. Thanks for all your hard work. I hope I never need to use your services, but thank you for doing it for so many other people.

  • Dan Cohen, Maccabee Seed Co. Davis CA

    The Chronology referenced here is a great, if skeletal summary of the epidemiological investigation. It is well worth reading. The graphic presentation of the trace-backs and trace-forwards, alone, are worth looking at.

    Epidemiological investigations depend on clear data sets that allow discrimination between possible sources. In O104:H4, the restaurant clusters provided the data sets to identify sprouts, they were the the loose threads to pull on in the midst of vast numbers of cases that lacked such structure. In fresh-cut outbreaks of O157:H7 in spinach and other salad greens, the packaging lot numbers provided such a discriminant.

    Given sprouts, and a highly probable source in one producer, fenugreek was identified as the common element in the sprout mixtures, the other ingredient sprouts (grown in Canada) were in other mixes without being associated with cases from people eating those mixtures and could be effectively ruled out.

    Epidemiology is closer to circumstantial evidence than to direct evidence in a trial. In this case they report more than 10,000 food samples tested with no outbreak strain detected. The considered opinion after the fact is that there is no validated test for O104:H4 on produce; that a very low infection number may be associated with the long time for pathology to develop; and that detection of low numbers of O104:H4 in produce is very difficult.

    Sometimes there is no smoking gun, or one can’t see the smoke, and waiting to find it means more people get sick or die. This may also be consistent with the lack of finding contaminated Egyptian fenugreek seeds with the currently used methods. I’m sure better methodology will be looked at.

    Although the EHEC crisis group was wound up, with the highly probable identification of a fenugreek seed source lot from Egypt as the outbreak source, there is still some question as to whether ill workers contaminated the sprout production, or pathogen containing sprouts made the workers ill.

    Contaminated seeds are the probable explanation. But one has to consider alternative circumstantial explanations and evidence, including what has been looked for and what has not been looked for — or at least reported. In this case, the independent small outbreak in France looks conclusive, the single lot of fenugreek seed is the factor in common.

    It would be more conclusive if there was a detailed investigation reported from France that could demonstrate that the two outbreaks were, in fact, independent of each other. That no one who was involved with the home-style sprout production for a festival in France had a link to travel to Germany during the outbreak. Particularly since the issue of infected but asymptomatic individuals has come up in several German cases. The immunological or infective status of the French sprout producers has not, to my knowledge, been reported.

    Accepting the high probability of fenugreek seeds as the source of the outbreak, how these became contaminated is still an important issue for future prevention.

    O104:H4 may now be in very large numbers of human hosts; how long are people carriers? There is the possibility of animal reservoirs, now or in the past.

    Even if the acute crisis is declining, the chronic or permanent conditions for O104:H4 still need to be looked at.

    Dan Cohen
    Maccabee Seed Company
    Davis, CA