Iowa has had the highest number of cases -- 143 -- of cyclosporiasis since late June, when the CDC first took notice in the outbreak. A total of 372 people in Iowa, Texas, Nebraska, Florida, Wisconsin, Illinois, Georgia, Missouri, Arkansas, Connecticut, Kansas, Minnesota, New Jersey, New York and Ohio have contracted the illness as of July 29.
The Iowa Department of Health said it was investigating a prepackaged salad mix as the source of the outbreaks in the state, but declined to name the brand or manufacturer. About 80 percent of the Iowa cases were exposed to the mix, which includes iceberg and romaine lettuce, carrots and red cabbage.
Health officials said they have removed the salad mix from the state's food supply chain.
The FDA was investigating the salad mix to see if it can be blamed for cases outside the state.
"FDA will continue to work with its federal, state and local partners in the investigation to determine whether this conclusion applies to the increased number of cases of cyclosporiasis in other states," the agency said in a statement. "The goal will be to combine information collected from other affected states with that provided by the state health authorities in Iowa to identify a specific food item linked to the illnesses."
Cyclosporiasis, caused by the single-celled parasite Cyclospora cayetanensis, presents as prolonged, watery diarrhea, cramping, bloating, nausea and fatigue. It spreads by ingesting feces and symptoms can last up to 57 days.
Notable deaths of 2014 [PHOTOS]