German health authorities say locally-grown bean sprouts are the likely source of an E. coli outbreak that is being blamed for the deaths of 22 people and made hundreds of people ill all over the world.

Lower Saxony agriculture ministry spokesman Gert Hahne says people are being told to stay away from eating the sprouts, which are often used in mixed salads.

"Many restaurants that suffered from an E. coli outbreak had those sprouts delivered," Hahne said.

He also said authorities would still keep their warning against eating tomatoes, cucumbers or lettuce in place for now.

Preliminary tests found that bean sprouts and other sprout varieties from an organic farm in the Uelzen area, between the northern cities of Hamburg and Hannover, could be the likely source of the contamination, Agriculture Minister Gert Lindemann said late Sunday.

The German farm was shut down Sunday and all of its produce, including fresh herbs, fruits, flowers and potatoes, was recalled

Two of the farm's employees were also infected with E. coli, Lindemann said. He said 18 different sprout mixtures from the farm were under suspicion — including sprouts of mung beans, broccoli, peas, chickpeas, garlic lentils and radishes.

E. coli O104:H4

The outbreak in Europe is thought to be caused by a microbe called Shiga toxin-producing E. coli or STEC, O104:H4. E. coli O104 is especially vicious because it doesn't take much bacteria to cause infection. The bug gets into the stomach and then attaches to the intestinal wall and secretes a toxin that destroys red blood cells and shuts down the kidneys.

Once securely inside the gut of one person, the bacteria can then start spreading person to person through the fecal-oral route. That happens when traces of feces on the hands get passed on, which is why hand-washing is so important.

The E. coli outbreak in Europe has mostly affected healthy adults, not children or the elderly. There also seems to be a higher rate of people progressing to more serious hemolytic uremic syndrome, or HUS, from the initial condition of bloody diarrhea, said Brett Finlay, a professor at the University of British Columbia who studies pathogenic strains of E. coli.

Lindemann noted that the sprouts at the farm are grown with steam in barrels — an ideal environment for bacteria to multiply. He said it is possible that the water had been contaminated with E. coli or that the sprout seeds, purchased in Germany and other countries, already contained the bacteria. He said the farmers had not used any manure.

Since the outbreak began in early May in Germany, 10 other European nations have also reported cases and there are at least four in the U.S. linked to Germany.

Reinhard Burger, head of the Robert Koch Institute, confirmed 21 people died from the illness in Germany and one in Sweden, another 2,153 have been sickened, including 627 people who have developed a rare complication that can cause kidney failure.

The World Health Organization cautioned people against taking antibiotics if they fall ill from E. coli because they could make the condition worse.

Anti-diarrhea medication also should be avoided because it stops the bacteria from quickly leaving the body, WHO epidemiologist Andrea Ellis told reporters in Geneva earlier this week.

The outbreak is considered the third-largest involving E. coli in recent world history, and it is already the deadliest. Twelve people died in a 1996 Japanese outbreak that reportedly made more than 9,000 people sick, and seven died in the Walkerton, Ont., tainted water outbreak in 2000.

Several aspects of this outbreak are unique, according to Robert Tauxe of the U.S. Centers for Disease Control and Prevention, which has been working with German health officials.

"First of all, it's mostly adults that are being affected rather than children, and a very large [number] are developing a kidney failure complication called HUS [hemolytic uremic syndrome]," Tauxe said in an interview with CBC News on Friday. "Whether that is because this organism is particularly virulent or whether it's because a lot of people have been exposed to something like a food contaminated with the organism is not completely clear."

To avoid food-borne illnesses, WHO recommends that people:

  • Wash their hands
  • Keep raw meat separate from other foods
  • Thoroughly cook their food
  • Wash fruits and vegetables, especially if eaten raw
  • Experts also recommend peeling raw fruits and vegetables if possible.
With files from The Associated Press