It has been the nation's largest E. coli outbreak in a decade.
The deaths have been reported in California, Arkansas, Minnesota and NY.
After the initial outbreak, the CDC issued a warning on romaine lettuce.
So far, five people in MI have been sickened in the outbreak.
The outbreak is over and romaine lettuce is no longer on the warning list, but reports of cases in three more states have come in, the CDC said. A Johns Hopkins Bloomberg School of Public Health study published in Public Health Reports in April of this year estimated that depending on the severity of the outbreak, a single foodborne illness incident can cost a fast food restaurant between $4,000 (no loss of revenue, fines or legal fees) to $1.9 million (fines, revenue lost, legal fees).
The growing season in Yuma, Arizona, where officials believe the contaminated lettuce was grown, has been over for more than a month.
Although it is safe to eat romaine lettuce again, that does not mean the risk of E. coli contamination is over. Many new cases there were two or three weeks ago, when contaminated lettuce is still sold. Of those, 89 people have been hospitalized, and 26 have developed hemolytic uremic syndrome.
Some patients said that not eating lettuce, but were in contact with those who suffered after consumption.
Genetic testing showed that the E. coli strain involved in the outbreak produces a specific type of "Shiga toxin" that causes more severe illness, according to Matthew Wise, the CDC deputy branch chief for outbreak response. Officials have still not targeted the exact source of the lettuce but have focused on Yuma, Arizona. Most of the people who got sick recently ate romaine lettuce in restaurants and stores.
The CDC estimates that foodborne illnesses affect 47.8 million people in the USA every year, putting 127,000 into the hospital and killing more than 3,000.