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Since early May 2011, consumers in 12 countries including Germany, other European and even North American regions have faced an outbreak of enterohemorrhagic Escherichia coli (EHEC). By July 22 authorities had registered 50 fatalities and 4318 infections connected to EHEC1 with new infections still being reported. Based on the beginning of diarrhea symptoms, the disease peak was on May 22. The number of related infections has now declined. Over a two-month period, authorities followed the outbreak like detectives to trace the infection to its source. They finally linked the origin of the infection to sprouts of fenugreek seeds imported from Egypt.2

The Dangerous EHEC Strain

The first sign of a problem occurred on May 19 when the Robert Koch Institute (RKI) reported an increase in cases of a severe illness called hemolytic-uremic syndrome (HUS) that can destroy blood cells and potentially lead to kidney failure. Six days later, on May 25 following an analysis of the first patient samples, the root cause of the outbreak was linked to bacteria Escherichia coli 0104:H4, a rare enterohemorrhagic strain which produces cytotoxins or so called Shiga-like toxins. Illness can be caused by just a small number of these bacteria, and immediate medical treatment may be necessary. Immediately after the bacteria strain was isolated and identified, the European Centre for Disease Prevention and Control (ECDC) gave an alert, and the RKI and the German Institute of Risk Assessment (BfR) warned against consuming tomatoes, leaf salad and cucumbers as potential sources of contamination.1 A positive EHEC result on May 26 for Spanish cucumber strengthened the suspicion, but could not be confirmed because the identified strains could not be linked to the infections. Although the RKI and BfR had reason to believe that the outbreak was connected to certain foodstuff, direct infection from animals to humans was also possible.1, 2

A Huge Demand for Food Tests

Meanwhile, as a result of the warning, authorities and food producers sent a huge number of samples to testing laboratories to identify the origin of the infection. SGS, which has test procedures to detect EHEC bacteria, was the recipient of many of these samples. Dr. Roy Hörner, laboratory manager at SGS Germany in Hamburg, was faced with massive testing volumes over a short period of time.

“We routinely perform extensive microbiological analyses for pathogenic organisms in our accredited laboratories. The analysis for EHEC is usually done by the detection of the Shiga-like toxins (ELISA) or characteristic genes (PCR),” Dr, Hörner noted. “After the crisis in northern Germany came up, we were faced with a lot of requests to perform tests for the detection of EHEC. The microbiological laboratory team devoted considerable efforts to build up the capacity for the increased number of samples while ensuring an absolutely safe laboratory process. This was successfully implemented in only a few days. We were able to support our clients during the crisis with reliable analyses and short turnaround times. Several hundred samples were analyzed during those days, and this helped our clients to fulfill the internal and external requirements for quality control.”

The Breakthrough

Despite these efforts, the origin of the infection could not be identified. Then on June 5, based on epidemiological data, the RKI pinpointed sprouts as the suspected source. Employees of a horticultural farm in Lower Saxony were found positive for Escherichia coli O104:H4, 2 but additional time was required to demonstrate a direct link between strains found on sprouts and in patients.3

The question of whether the farm was the source or simply a distributor also remained. Evidence that in several cases homegrown sprouts were contaminated finally resulted in the identification of fenugreek seeds imported from Egypt as a potential source of the HUS/EHEC outbreak – the largest ever in Germany and, based on the number of reported HUS cases, the largest outbreak to date anywhere in the world. The outbreak officially ended on July 27, three weeks after no more new cases were reported.

SGS, the global leader in third-party testing, provides services to the whole food supply chain from farm to fork to help assure that your products are fit for the market. For more information, contact your local sales representative.

1 Robert Koch Institute
2 German Institute of Risk Assessment
3 Informationsdienst Wissenschaft

Ron Wacker, PhD
Global Business Development Manager
Food Testing
SGS Germany GmbH

t: +49 6039 4696540


SGS is the world’s leading inspection, verification, testing and certification company. SGS is recognized as the global benchmark for quality and integrity. With 67,000 employees, SGS operates a network of over 1,250 offices and laboratories around the world.