Almost 100 people have fallen ill in the US after eating lettuce apparently contaminated with E. coli bacteria.
The US government is investigating whether romaine lettuce from Yuma in Arizona could have been contaminated with the bacteria, according to the Centers for Disease Control and Prevention (CDC).
As of Friday, at least 98 people in 22 states have fallen sick, the centre reports.
Forty-six of these have been treated in hospital.
Pennsylvania is the worst affected state, with 18 people falling ill, while 16 have become sick in California.
The total number could be higher because of the time between when a person becomes ill with E. coli and the illness being reported to CDC.
People who eat contaminated food usually become ill between two to eight days later, and symptoms usually include diarrhoea, stomach cramps and vomiting.
The bacteria is usually spread through human or animal faeces, contaminated water or improper handling.
Most infections are mild and the majority of people recover within a week, however some cases can be life-threatening.
Restaurants across the US are replacing romaine lettuce with alternatives if they cannot confirm its origin or source it from outside of Yuma, the CDC said.
Just Salad, which has 28 locations in New York, New Jersey, Philadelphia and Chicago, says it saw a spike in business this week after a social media blitz to assure customers that its romaine comes from Salinas, California.
The CDC first announced a multi-state outbreak of E. coli on April 10.
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By the end of last week, it was advising people not to eat whole heads of romaine or salad mixes that might contain romaine unless they were sure they had not been grown in Yuma.
The government is investigating the outbreak.