The Douglas County Health Department has confirmed one case of E. coli O157:H7 related to the outbreak in romaine lettuce grown in the Yuma, Arizona, region.
But the last shipment of romaine from Yuma left on April 16 and the growing season there is over. It is unlikely that any romaine lettuce from the Yuma area still is available in people's homes, stores or restaurants due to its 21-day shelf life.
Health officials say almost two dozen more cases of a food poisoning outbreak linked to romaine lettuce grown in Arizona have been reported.
That means that the agency is no longer advising consumers to avoid buying romaine lettuce in connection with the outbreak.
Since last reported a week ago, 23 people have fallen ill to E. coli, bringing the total to 172 ill people from 32 states.
Newly reported cases are people who became sick two to three weeks ago, still within the window when contaminated romaine was available for sale.
Most of the illnesses in the outbreak are not linked to the romaine lettuce grown at that farm. The CDC also noted that 75 people have been hospitalized.
It's the worst outbreak of E. coli since 2006 when illnesses traced to spinach killed three and sickened more than 270. The strain linked to chopped romaine lettuce is a Shiga toxin-producing E. coli, which can cause severe stomach cramps, diarrhea and vomiting, the CDC said.
The CDC and Food and Drug Administration have struggled for more than a month to pinpoint a source for the contamination, which became evident in early April.