Cook sprouts to be safe, E. coli experts say

The head of Germany's national disease control centre says investigators have determined that locally grown vegetable sprouts are the cause of the European E. coli outbreak that has killed 31 and made more than 3,000 people sick.

Warnings lifted for other vegetables as death toll rises to 31

It's little surprise that sprouts are behind the world's deadliest E. coli outbreak, experts say.

Sprouts need warm and humid conditions to grow — precisely the same conditions required by bugs like E. coli and salmonella to thrive. And raw sprouts have been blamed before in food poisoning outbreaks, in the U.S. and a large outbreak in Japan in 1996. 

After more than a month of searching, health officials announced Friday they had determined that sprouts from an organic farm in the northern German village of Bienenbuettel were the source of the outbreak that has killed 31 people, sickened nearly 3,100 and prompted much of Europe to shun vegetables.

"It was like a crime thriller where you have to find the bad guy," said Helmut Tschiersky-Schoeneburg, head of Germany's consumer protection agency.

German officials don't know which kind of spouts caused the outbreak. The organic farm linked to the outbreak grew a wide variety, including alfalfa, onion and radish.

Sprouts are grown in water from seeds, which are rinsed daily.

They can be grown from numerous kinds of vegetables and are often eaten raw in salads and sandwiches. 

Officials in Germany say they're not yet sure whether the sprout seeds were infected or whether the sprouts got contaminated by dirty water.

Sprout seed hazard

Public health agencies have long been concerned about the risks of bacterial contamination of water used to produce sprouts.

E. coli can stick to the surface of sprout seeds.

"They can lay dormant on the seeds for months," said Stephen Smith, a microbiologist at Trinity College in Dublin.

Unfortunately for sprout-eaters, the germs are then inside the sprout as well as outside.

At that point, "washing has no effect," Smith said.

The European Food Safety Authority doesn't recommend avoiding certain foods, but advises consumers to take basic precautions, like washing all fruits and vegetables with clean water and peeling or cooking them when possible.

For now, German authorities are recommending people avoid all sprouts.

Both the Canadian Food Inspection Agency and the U.S. Food and Drug Administration recommend children, the elderly, pregnant women and people with weakened immune systems avoid eating any kind of raw sprouts. The U.S. agency also recommends cooking sprouts thoroughly to reduce the risk of illness.

Because most sprouts — including alfalfa, bean, and mung — are eaten raw, they're not exposed to temperatures high enough to kill bacteria.

But experts say it's not necessary to ditch sprouts entirely because they are a good source of protein and vitamins.

"It's not that all sprouts are bad," Smith said. "But if you're desperate to eat sprouts and you want to be safe, try stir-frying them first."

Bob Sanderson, president of the U.S.-based International Sprout Growers Association, said the industry is working to update food safety guidelines issued by the FDA more than a decade ago.