Health officials are eyeing salad mix in a multi-state outbreak of cyclospora, a stomach-sickening parasite contracted through contaminated food.

The Nebraska Department of Health announced today that a prepackaged salad mix was the source of the stomach bug that has sickened 78 Nebraskans since mid-June. The Iowa Department of Health said the same, blaming a mixture of iceberg and romaine lettuce, carrots and red cabbage for the diarrhea-causing parasite contracted by at least 143 Iowans.

Read about how produce is a common culprit in food-borne illness.

At least 80 percent Iowa's cyclospora patients had eaten the prepackaged salad mix, according to an investigation by the state's health department. But officials have yet to name the salad's manufacturer, emphasizing that it's no longer on store shelves.

"Iowans should continue eating salads, as the implicated prepackaged mix is no longer in the state's food supply chain," Steven Mandernach, chief of the Food and Consumer Safety Bureau of the Iowa Department of Inspections and Appeals, said in a statement.

More than 370 people have contracted the stomach bug in 15 states, according to the U.S. Food and Drug Administration. The source of the infection in states other than Nebraska and Iowa, which include Texas, Wisconsin, Arkansas, Connecticut, Florida, Georgia, Illinois, Kansas, Minnesota, Missouri, New Jersey, New York and Ohio, remains unclear.

"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 FDA said in a statement. "Should a specific food item be identified, the FDA, the U.S. Centers for Disease Control and Prevention, state and local partners will work to track it to its source, determine why the outbreak occurred, and if contamination is still a risk, implement preventive action, which will help to keep an outbreak like this from happening again."

The infection, which beyond diarrhea can cause fatigue, weight loss, stomach cramps, vomiting, muscle aches and low-grade fever, can be cleared with antibiotics. But without treatment, the symptoms can linger for months.

People who are "in poor health or who have weakened immune systems" are more likely to have a severe or prolonged illness, according to the CDC.