That brings the total number of cases to 172, the U.S. Centers for Disease Control and Prevention said.
"Romaine lettuce from the Yuma growing region is past its shelf life and is probably no longer being sold in stores or served in restaurants", the CDC said in a news release.
It's finally safe to eat romaine lettuce again.
A Douglas County resident has tested positive for E. coli linked to the romaine lettuce grown in the Yuma, Arizona, region.
Newly reported cases are people who became sick two to three weeks ago, still within the window when contaminated romaine was available for sale.
DHS officials noted "it appears the romaine is no longer at stores or restaurants".
The CDC said 20 people had developed a severe outcome of E. coli infection called hemolytic uremic syndrome.
Health officials say almost two dozen more cases of a food poisoning outbreak linked to romaine lettuce grown in Arizona have been reported.
The CDC added that the last date of harvest for the romaine lettuce from the Yuma growing region was April 16th.
The Public Health Agency of Canada has identified people in several Canadian provinces infected with the same DNA fingerprint of E. coli O157:H7.
One person died in California. A previous warning was limited to chopped forms of romaine, including salads and salad mixes.
It's the worst outbreak of E. coli since 2006 when illnesses traced to spinach killed three and sickened more than 270.
Officials have warned against continuing consumption of Romaine lettuce from the Yuma, Arizona growing region. The Health Department may never be able to pinpoint the specific source of the infection.