CDC: You can eat some romaine lettuce; check labels

Days after warning consumers to avoid all romaine lettuce, federal health officials are revising their guidance.

The CDC and the FDA now say that you should avoid romaine lettuce from the Central Coast regions of northern and central California. The new guidance is based on an investigation into an E. coli outbreak that has sickened dozens of people.

You should check the labels on bags or boxes of romaine lettuce to see where it was harvested, the CDC said. Harvest regions such as Yuma in Arizona, the California desert growing region near Imperial County and Riverside County, the state of Florida, and Mexico are not linked to the outbreak, officials said.

However, if you don't know where the lettuce is from, do not eat it, the CDC said.

The CDC is advising restaurants and food retailers to stop serving and selling romaine lettuce, including salads and salad mixes with romaine, from California's Central Coast.

The outbreak strain of E. coli has infected more than 40 people in a dozen U.S. states so far, according to public health investigators. On top of that, Canada's Public Health Agency has identified patients infected with the same DNA fingerprint of E. coli.

E. coli bacteria are found in nature, such as in the environment, in food, and in the intestines of people and animals. Most E. coli strains are harmless and indeed part of a healthy gut.

But strains that produce Shiga toxin cause illnesses. Symptoms of Shiga toxin-producing E. coli infection include stomach cramps, diarrhea (sometimes bloody), vomiting, and fever, according to the CDC. Most people get better in a week or less, but some can experience life-threatening infection.