German officials said sprouts from an organic farm near the town of Uelzen played a role in the country’s lethal E. coli outbreak, returning suspicions to the region where the infections began last month.

The outbreak has killed 22 people and sickened 2,333, according to the European Centre for Disease Prevention and Control, and put pressure on hospitals near the hard-hit areas of Hamburg and Bremen. At least one worker at the farm near Uelzen has been infected with E. coli and it supplied places where the bacterium was found, Gert Lindemann, the state agriculture minister, told reporters in Hanover yesterday.

German officials initially blamed Spanish cucumbers, causing outrage in the southern European nation. Sprouts may have been overlooked at first because they’re used in an array of dishes including salads and sandwiches, and as a garnish, said Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota in Minneapolis.

“People don’t think of them as produce,” Osterholm said in a telephone interview today. Even so, “sprouts should have just screamed at the investigators” after they were implicated in earlier outbreaks, he said. E. coli-contaminated radish sprouts were blamed for sickening about 6,000 people in Japan in 1996, according to a 1997 report by the U.S. Centers for Disease Control and Prevention.

About 18 different sprouts grown by the company, including bean, broccoli and garlic, are under investigation, Lindemann said yesterday. The sprouts can’t be solely to blame for the outbreak, he added.

Pinpointing where and how the germ entered the food chain will enable authorities to control the outbreak, which the European Centre for Disease Prevention said caused 21 deaths in Germany and one in Sweden.

The organic farm, called Gaertnerhof Bienenbuettel, said in a statement it had informed customers and was “shocked and concerned” by the news. Only water and seeds are used to grow sprouts and no animal manure is used as fertilizer in the process, Klaus Verbeck, the owner, said in an interview with Neuen Osnabruecker Zeitung today. Black-and-white cows graze in a nearby field. Cattle are the main reservoir for E. coli.

More than a quarter of the people reported to have been sickened by the new enterohemorrhagic E. coli bacteria developed a potentially deadly kidney complication known as hemolytic uremic syndrome.

“The source of the outbreak is under investigation, but contaminated food seems the most likely vehicle of infection,” the Stockholm-based ECDC said in a statement.

Officials in Lower Saxony warned against eating sprouts, tomatoes, cucumber as well as salads and said results of more definitive tests may be released today.

It’s unclear whether the bacteria came from the water the sprout seeds were grown in or the seedlings themselves, which came both from within Germany and from outside the country, Lindemann said. The farm has been shut down, he said.

Sprouts were either delivered directly by the farm or through a distributor to the states of Hamburg, Schleswig- Holstein, Mecklenburg-Vorpommern, Lower Saxony and Hesse, Lindemann said.

READ MORE: BLOOMBERG