Ten cases of E.coli infection in Minnesota residents are now identified and linked to the multi-state outbreak.
"Most of the illnesses in this outbreak are not linked to romaine lettuce from this farm and are associated with chopped romaine lettuce (not whole head lettuce)", the agency said in a statement, adding that other farms are being investigated as well. The sick people range in age from 1 to 88 with a median age of 30.
Health officials connected the outbreak to romaine lettuce grown in Yuma, Ariz. which provides most of the romaine sold in the US during the winter.
Though the contaminated lettuce is thought to come exclusively from the Yuma area, another two dozen farms are under investigation, and the FDA now believes that only the Alaska illnesses were related to Harrison's romaine.
However, the outbreak hasn't scared away many restaurants from keeping romaine on their menu.
Though a farm in Yuma, Arizona, was identified as the general source of whole-head romaine that sickened eight inmates in Alaska, health officials are not certain whether the contamination occurred in the field or along the packaging and distribution chain, according to the FDA. For example, Salinas, Calif., is also a big romaine-producing area. "If you do not know if the lettuce in a salad mix is romaine, do not eat it".
Ideally, investigators will be able to isolate the E. coli strain from the source and use DNA sequencing to match it with the people who got sick, said Critzer.
Symptoms of illness caused by E. coli O157 typically include stomach cramps and diarrhea, often with bloody stools, but only a low-grade or no fever.
The bacteria can spread through ruminants, animals like cattle, sheep, goats, buffalo, elk, and deer; water; the environment and people, Dr. Robert Tauxe, director of CDC's Division of Foodborne, Waterborne, and Environmental Diseases, said previously. According to the CDC, 63% of the people who have gotten sick are female.
Federal officials first warned of the problem in April after people started getting sick from greens they ate March 22 to 31. In the CDCs most recent figures, which were released last week, the outbreak has resulted in 121 E. coli cases and 52 hospitalizations nationwide. The largest American E. coli flare-up since 2006, when contaminated spinach was the culprit, is expected to continue for several weeks.