52 people have been hospitalised and 14 of them with kidney failure among the sickened people. This is why the percentage of those requiring hospitalization is higher than what is typically seen with E. coli outbreaks, where, on average, only 30% of individuals end up in the hospital.
Kentucky, Massachusetts and Utah were added to the list affected by the outbreak, bringing the total number of states to 25.
As discussed by Matthew Wise, PhD, MPH, deputy branch chief for Outbreak Response at the CDC in last week's media telebriefing, the outbreak strain "is one that tends to cause more severe illness based on the kind of toxin it produces".
Most people start to experience symptoms of an E. coli infection three or four days after eating contaminated food, although it may take as few as two days or as many as eight.
The bacteria normally live in the intestines of animals, including cows and pigs, and in the 1990s, most E. coli cases were associated with contaminated hamburger. "I mean, candidly, that's ridiculous", Marler said.
The outbreak encompasses basically all forms of romaine lettuce from the Yuma, Arizona growing region. But investigators have not specified when and where that lettuce became contaminated with the unsafe bacteria, and the farm has not been linked to other cases.
The CDC has also advised consumers not eat lettuce from the Yuma region and urges people to inquire about the source of their lettuce before purchasing.
California now leads the nation with 24 cases, followed by Pennsylvania with 20 and Idaho with 11. The newest update includes illnesses starting as recently as April 21.
"The agency is investigating dozens of other fields as potential sources of the chopped romaine lettuce and will share information as it becomes available", the FDA promises.
More than 120 cases of E-coli linked to romaine lettuce have been reported in 25 states since the outbreak began in March.