The European Union banned the import of certain Egyptian seeds and beans Tuesday following an official report that a single batch of well-travelled Egyptian fenugreek seeds probably caused two European outbreaks of E. coli poisoning that have sickened 4,211 people and killed at least 50.

A task force of health officials set up by the European Food Safety Authority (EFSA) reported that “one lot of fenugreek seeds imported from Egypt is the most likely common link between the two outbreaks.”

And it is likely that contaminated seeds remain on the European market, leading the EU to reiterate its warning and ban the import of Egyptian seeds until October 31.

While the seeds that triggered epidemics in northern Germany and in Bordeaux, France, travelled different routes, both lots originated in Egypt, investigators concluded.

Both were traced back a year and a half to a shipment of 33,000 pounds (15,000 kg) of fenugreek seeds, Lot No. 48088, that was loaded onto a ship at the Egyptian port of Damietta on Nov. 24, 2009.  That ship steamed to Antwerp, Belgium, and the seeds were barged to Rotterdam to clear customs.

The sealed container was trucked into Germany to an unidentified importer, who resold most of the lot. An unidentified German company then resold about 150 pounds of the seeds to the German sprouter, Gartnerhof Bienenbuttel, which is believed to be the source of the sprouts that caused the enormous outbreak of E. coli poisoning in northern Germany.

Meanwhile, the German importer also sold about 800 pounds of sprout seed to the English company Thompson & Morgan, which repackaged the seeds into 1.75-ounce (50 grams) packages. Those packages were shipped to a French distributor, who resold the seeds to about 200 garden centers around France.

Investigators believe that one of those packets was the source of the second European outbreak, which has sickened 16 people in the Bordeaux area.

Because more contaminated seeds could be in circulation, “it seems appropriate to consider all lots of fenugreek from the (Egyptian) exporter as suspect,” the EFSA report concluded. Trace-forward findings indicate the German importer sold seeds from the suspected lot to 70 companies.

Even a negative laboratory test of those seeds “cannot be interpreted  as proof that a batch is not contaminated,” the report says.  EFSA also said the seeds were likely contaminated with E. coli O104:H4 at some point before leaving the importer.  A “production or distribution process” might have allowed contamination by human or animal fecal material.

Europeans have been alarmed by watching thousands of people sickened by a few miniscule sprout seeds.  But U.S. experts have seen this before.

“Sprouts are susceptible as a raw vegetable product, ” says Ben Miller of the Minnesota Department of Agriculture.  “The seed is likely to come into contact with soil, which is a great place to become contaminated with salmonella or E. coli.   And the seed itself provides an ideal space for the pathogen to settle in for long periods of time.”

The shelf life of the seed can be up to five years, Miller said.  And the bacteria will remain.

Under the right, or wrong, circumstances, a single bacterium on a single seed can end up contaminating an entire batch of sprouts, he said.

Most sprouters are small, local, independent farms that probably do not produce their own seed, Miller said.  The seed is cheap and easy to ship, so the sprouter is likely to have it shipped.

Europe’s twin outbreaks, caused by seeds that were shipped from Egypt 18 months earlier, appear to be a classic example of that.

“Sprouts are a great vehicle for all kinds of pathogens,” Miller said. “But we have lots of questions.  Will there be an environmental investigation in Egypt?  Where were these sprouts growing?  Why were they so susceptible to this pathogen?  Did it originate with cows? With human waste?”