The U.S. Food and Drug Administration said on Wednesday the harvest season for romaine lettuce, linked to the multi-state E. coli outbreak, was over and it was unlikely that it was still available in stores due to its 21-day shelf life.
The reported strain of E. coli, which produces poisonous substances known as Shiga toxins, can cause severe abdominal cramps, bloody diarrhea and vomiting.
The last shipments of romaine lettuce from Yuma, Arizona were harvested on April 16, according to the FDA.
Twenty-three more people fell ill since the last update on May 9, bringing the total to 172 people from 32 states, the CDC said on Wednesday.
Three more states Iowa, Nebraska, and Oregon have also reported cases, the CDC said.