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Published July 04, 2011, 04:44 AM

Lessons learned from E. coli outbreak?

KNOXVILLE, Tenn. — In following the story of the E. coli outbreak in Germany, we were intrigued when Germany determined that the point of origin was raw bean sprouts produced on an organic farm despite tests on bean sprout samples turning out negative for E. coli 0104:H4, the bacteria responsible for at least 30 deaths in Germany and one in Sweden. More than 800 people have come down with hemolytic uremic syndrome, permanent damage of the kidneys. In all, more than 3,200 people have been sickened so far.

By: Daryll E. Ray and Harwood D. Schaffer,

KNOXVILLE, Tenn. — In following the story of the E. coli outbreak in Germany, we were intrigued when Germany determined that the point of origin was raw bean sprouts produced on an organic farm despite tests on bean sprout samples turning out negative for E. coli 0104:H4, the bacteria responsible for at least 30 deaths in Germany and one in Sweden. More than 800 people have come down with hemolytic uremic syndrome, permanent damage of the kidneys. In all, more than 3,200 people have been sickened so far.

It turns out that Germany used a variety of evolving investigative and statistical techniques as it sought to identify the source material.

Investigating the outbreak

As the outbreak began, federal and state authorities conducted an initial set of interviews and two epidemiological studies to identify the source of the illnesses. The first two studies “showed that (those who became ill) consumed raw tomatoes, cucumbers and lettuce significantly more often than healthy study participants. These findings were complemented by results of another case-control study conducted among affected customers of a canteen that revealed a strong association between the consumption of foods from the salad bar and (the E. coli infection).”

Because E. coli was found on cucumbers from Spain, they initially were declared the cause of the outbreak. It later was found that the E. coli serotype on the cucumbers was different from the serotype that caused the illnesses of people who lived in or had visited northern Germany.

To minimize illnesses, health officials need to identify potential disease vectors as quickly as possible so they can warn people to avoid these foods.

When two studies failed to identify the source of the growing number of illnesses they conducted a “‘recipe-based restaurant cohort study’ (that allowed German researchers to narrow) down the source of the infection to the consumption of sprouts. It was possible to apply this methodological approach only after a sufficient number of restaurant customers could be identified to ensure adequate statistical power of this analysis.

To ascertain the consumption of raw fruit and vegetables by patients and controls more objectively and less dependently on memory, the Robert Koch Institute (Part of the Germany Federal Ministry of Health and one of the investigating agencies) used this approach in the ‘recipe-based restaurant cohort study”:

n Five groups (travel groups, clubs, etc.) that comprised a total of 112 participants and included 19 individuals who acquired EHEC infection were questioned regarding the foods they consumed after eating in a common restaurant.

n The menus ordered by the participants were identified by means of order lists and meal receipts.

n The restaurant kitchen was questioned in detail regarding the preparation and the type and quantity of ingredients in each menu ordered by any of the study participants.

n Available photographs taken by travel group members were analyzed to confirm which food items, including toppings, were seen on the plates.

The data thus gathered was analyzed in a cohort approach that permits the retrospective estimation of the relative risk of infection for the restaurant customers. Results of this analysis showed that customers who ate sprouts had an 8.6-fold increased risk of illness compared with those who did not. This study also revealed that 100 percent of those who contracted the illness had eaten sprouts.

Learning from it

There are lessons to be learned.

To minimize the loss of life and the spread of a foodborne illness, classes of products may be indicated rather than the product of specific producers. As we have seen in this incident and similar ones in the U.S., producers of similar products will be negatively affected. Stopping the loss of life and the spread of the disease is of first importance. As a consequence, we may need to think of ways to protect producers from the negative effect of a food warning.

German authorities needed to hone their investigative techniques as early procedures failed to identify the source of the outbreak.

Better coordination among all agencies involved is essential, and it would be best if one agency were designated as incident commander with the authority to move resources around as circumstances require.

During the initial days, different and incomplete messages from various agencies involved in this outbreak led to some avoidable confusion.

Editor’s Note: Ray holds the Blasingame Chair of Excellence in Agricultural Policy, Institute of Agriculture, University of Tennessee, and is the director of the university’s Agricultural Policy Analysis Center. Schaffer is a research assistant Professor at APAC.

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