American consumers have been told to throw out any store-bought romaine lettuce as an E Coli outbreak has hospitalised dozens.
All types of romaine grown in a particular region of Arizona are at risk of spreading the disease, the Centers for Disease Control (CDC) said.
Regulators broadened a previous warning after people were sickened in Alaska, a state that is separated from Arizona by thousands of kilometres.
Infections have now been reported in 16 different states. The outbreak has rippled across the entire country, with cases registered on both coasts.
Unless eaters know their lettuce has not come from the Yuma, Arizona epicentre, authorities said, it is better to err on the side of caution and skip it.
“This includes whole heads and hearts of romaine, chopped romaine, and salads and salad mixes containing romaine lettuce. If you do not know if the lettuce is romaine, do not eat it and throw it away”, the health agency warned.
The same goes for eating at restaurants, the CDC said. Health authorities also recommend washing drawers and shelves that held romaine lettuce.
Some 53 cases have been reported since this strain of E Coli began spreading, with 31 people sent to the hospital. None of them have died.