(CNN) -- The US Centers for Disease Control and Prevention has expanded its warning about an E. coli outbreak connected to romaine lettuce to cover all forms of romaine, including whole heads and hearts of romaine grown in the Yuma, Arizona, growing area.
A previous warning was limited to chopped forms of romaine, including salads and salad mixes.
The CDC based the new warning on eight new cases of acute gastroenteritis at a correctional facility in Nome, Alaska, that appear to be connected to the current outbreak affecting 53 people in 16 states. Thirty-one of those have been hospitalized, the CDC said, and although no one has died, five people have developed a type of kidney failure called hemolytic uremic syndrome.
"Because this outbreak involves a strain of E. coli bacteria that can lead to serious illness including kidney failure, state officials are asking Alaskans to follow CDC recommendations and avoid any romaine lettuce products that could be contaminated," said a news release from the state of Alaska.
While the current cases are connected to the Yuma, Arizona, area, the CDC warns that package labels do not often identify growing regions. Therefore, consumers should throw out any romaine lettuce in their homes, even if partially eaten, and avoid eating romaine at restaurants unless the establishment can confirm that the lettuce is not from Yuma. No common grower, supplier, distributor or brand from the Yuma area has been identified.
Symptoms of this strain of E. coli include severe stomach cramps, vomiting, and diarrhea, which is often bloody, officials said. Anyone with these symptoms should see a health provider immediately and report their infection to local departments of health and social services.
Infections from these bacteria often take three to four days to develop. Most are gone within a week, but some can last longer and be more severe, the CDC said.
E. coli are a diverse family of bacteria that can be found in the environment, in foods and in the intestines of people and animals. Most strains are harmless. To avoid becoming infected with a harmful strain, the CDC recommends using proper hygiene; cooking meat at proper temperatures; avoiding raw milk, unpasteurized dairy products and juices; and not swallowing water when swimming.
Since lettuce is suspected to be the cause of the current outbreak, would it help to wash your greens before eating? No, said Ian Williams, chief of the CDC's Outbreak Response and Prevention Branch.
"This bacteria can actually get inside the lettuce leaf," he said. "Washing it doesn't make it safe."