Updated 6:19 p.m. ET
The multi-state cyclospora outbreak has now grown to 400 cases, federal health officials announced Friday.
As of the evening of August 1st, 400 cases of the infection caused by a parasite have been reported from 17 health departments: Iowa, Texas, Nebraska, Florida, Wisconsin, New York City, Georgia, Illinois, Arkansas, Kansas, Louisiana, Missouri, Connecticut, Minnesota, New Jersey, New York and Ohio.
Louisiana became the latest state added to the list, with two cases confirmed there. Health officials say those two illnesses occurred in early July.
Iowa has the most cases (146 infected), followed by Texas (113) and Nebraska (81).
At least 22 people have been hospitalized nationwide, the Centers for Disease Control and Prevention reported.
Cyclospora, a parasite, causes the intestinal illness cyclosporiasis if people eat or drink food and water contaminated with the bug. Symptoms include nausea, diarrhea, abdominal pain, cramping, flu-like aches and pains, and a low-grade fever. Health officials have said diarrhea can last nearly two months.
Health departments from both Iowa and Nebraska have announced their investigations revealed prepackaged bagged salad mixes are linked to the outbreak.
Nebraska officials have honed in on a particular salad mix that includes iceberg and romaine lettuce, along with red cabbage and carrots that were sold nationally. They said no locally-grown produce was part of this outbreak.
"Our investigation implicated prepackaged, prewashed, salad mix as the cause of this outbreak," the Nebraska Department of Health & Human Services said in a statement.
Iowa health officials also flagged a bagged salad mix with the same produce ingredients, pointing out exposure to the products could have occurred at more than 50 possible sites in the state, including more than 30 groceries and more than 15 restaurants.
The health department, however, emphasized the salad mix is no longer in the food supply chain in Iowa and that bagged salads and other vegetables are safe to eat.
saying its investigation "found that illness clusters at four restaurant were traced to a common supplier, Taylor Farms de Mexico."
The FDA says its investigation has not implicated consumer packages sold in grocery stores, and it's not yet clear whether cases reported in other states besides Iowa and Nebraska are all part of the same outbreak. The investigation into those cases continues.
Neither Nebraska nor Iowa officials named the brand of bagged salad mix suspected in the outbreak. CBS News chief medical correspondentthat both states cite laws preventing investigators from naming brands or companies if the product is no longer believed to pose a public health threat.
"The CDC told us that just because a certain brand of salad is infected, it doesn't mean that brand is the ultimate source of the infection," said LaPook. "For example, it could come from a common distributor or a common processing plant which involves a lot of other brands."
The FDA has upped its team of investigators at the agency's headquarters dedicated to finding the source of the outbreak from seven people to 15, it said in an August 1 statement. Additionally, investigators in 10 field offices around the country are working to solve the source of the outbreak.