The latest numbers revealed 149 people in 29 states had reported illnesses in the food poisoning outbreak.
Of those 149, at least 64 have been hospitalized. Seventeen suffered a type of life-threatening kidney failure known as hemolytic uremic syndrome. And last week, one death was reported in California.
The CDC has asked consumers to avoid buying or eating romaine lettuce at any grocery store or restaurant unless they can confirm the vegetable was not grown in Yuma, Arizona, which provides most of the romaine sold in the United States during the winter.
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"This advice includes whole heads and hearts of romaine, chopped romaine, baby romaine, organic romaine, and salads and salad mixes containing romaine lettuce," the CDC said. "If you do not know if the lettuce in a salad mix is romaine, do not eat it."
The outbreak began in March, with illnesses first reported in late April. But officials warn that with the delayed reporting, there may have been more cases.
The strain of E. coli involved, O157:H7, is known to be especially complicated and is associated with higher hospitalization rates. Compared to other strains, this bacteria binds more strongly to blood vessels that line organs such as the gut, the kidneys and the brain.
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Symptoms of illness typically begin three to four days after consumption and include diarrhea, stomach cramps and vomiting. If you’re experiencing such symptoms, the CDC recommends you seek treatment.
According to the agency, most people recover in five to seven days with the appropriate treatment, but antibiotics are not recommended if an E. coli O157 infection is suspected until it is ruled out.
Read the full announcement at CDC.gov.