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One person has died and 23 more people have been reported sick in an outbreak of E. coli food poisoning linked to romaine lettuce, federal health officials said Wednesday.

Three more states have been affected by the outbreak, bringing the total to 121 people sickened in 25 states, the Centers for Disease Control and Prevention said.

“One death was reported from California,” the CDC said.

A colorized 2006 scanning electron microscope image of E. coli bacteria of the O157:H7 strain that produces a powerful toxin which can cause illness. Janice Haney Carr / CDC via AP

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It’s the worst outbreak of E. coli since 2006 when illnesses traced to spinach killed three and sickened more than 270.

More than half of those who have become ill in the outbreak have been hospitalized, the CDC said. The E. coli strain that is making people sick produces a toxin called Shiga toxin that can damage organs and cause a severe form of kidney failure called hemolytic uremic syndrome. The CDC says 14 people so far have this kidney damage, which can kill.

All the contaminated lettuce has been traced to farms in the Yuma, Arizona area.

“Do not eat or buy romaine lettuce unless you can confirm it is not from the Yuma, Arizona growing region. Restaurants and retailers should not serve or sell any romaine lettuce from the Yuma, Arizona growing region,” the CDC said.

E. Coli outbreak cases map, state by state

“If you do not know whether lettuce is romaine, do not eat it. This includes lettuce in a salad mix. Package labels often do not identify growing regions. CDC is advising consumers not to eat or buy romaine lettuce if they do not know where it was grown.”

“People get sick from Shiga toxin-producing E. coli an average of three to four days after swallowing the germ. Most people get diarrhea (often bloody), severe stomach cramps and vomiting,” the CDC said.

“Most people recover within a week, but some illnesses can last longer and be more severe.”

One farm has been identified as a source of contaminated romaine. The CDC and the Food and Drug Administration are checking at least two dozen other farms as possible sources of contaminated romaine.

The growing season for lettuce is over in Yuma, but the FDA and CDC said they could not guarantee that the outbreak is over. They said it is possible some affected romaine is still on grocery shelves or in people’s refrigerators.