"Consumers who have any type of romaine lettuce in their home should not eat it and should throw it away, even if some of it was eaten and no one has gotten sick", the CDC said.
The alert covers all forms of romaine lettuce, including whole heads, hearts, bags and boxes of precut romaine, and salad mixes containing romaine.
No brand names have been identified and no recall was ordered.
Epidemiologic evidence from the United States and Canada indicates that romaine lettuce is a likely source of the outbreak.
The Centers for Disease Control and Prevention (CDC) issued a broad alert on Tuesday warning of an E. coli outbreak linked to the popular type of lettuce.
Most people infected by the bacteria get better within five to seven days, though this particular strain of E. coli tends to cause more severe illness.
Illnesses started in October.
In the meantime, CDC officials say consumers should not eat any romaine lettuce, and retailers and restaurants should not serve any romaine lettuce. "Contact your healthcare provider if you have diarrhea that lasts for more than 3 days or is accompanied by high fever, blood in the stool, or so much vomiting that you can not keep liquids down and you pass very little urine".
Report your illness to the health department.
This outbreak is not related to the previous 2018 E. coli infections linked to romaine lettuce. Thirteen were hospitalized, including one person who developed a type of kidney failure.
Go here for more information from the CDC.
There is another E. coli outbreak in the USA, and the agency has traced it back - yet again - to the usual suspect: the crunchy and leafy green served across the country.
Individuals should seek medical help if diarrhea lasts for more than three days or if it is accompanied by high fever, blood in the stool or an inability to keep liquids down because of vomiting.