(ABC NEWS) -- A farm in Mexico is responsible for an outbreak of cyclospora in at least two of the 16 affected states, the Food and Drug Administration announced today.
So far, 400 people have been infected and 22 have been hospitalized with the stomach bug-like illness that's caused by a one-celled parasite and spread through contaminated food.
An FDA investigation traced the illness to Taylor Farms in Mexico, which provided salads to restaurants in Nebraska and Iowa, the FDA said in a statement. Grocery store salads have not been implicated.
"It is not yet clear whether the cases reported from other states are all part of the same outbreak," the FDA statement reads. "The investigation of increased cases of cyclosporiasis in other states continues."
Federal officials had been eyeing prepackaged salad mixes in the outbreak after health officials in Nebraska and Iowa determined salad greens to be the cause. But state and federal laws kept them from announcing the brand names or farms.
The Nebraska Department of Health announced Tuesday that a prepackaged salad mix was the source of the stomach bug that had sickened 78 Nebraskans since mid-June. The Iowa Department of Health said the same, tracing the diarrhea-causing parasite contracted by at least 143 Iowans to a mixture of iceberg and romaine lettuce, carrots and red cabbage.
At least 80 percent Iowa's cyclospora patients had consumed the prepackaged salad mix, according to an investigation by the state's health department. But officials did not name the salad's manufacturer, emphasizing that the greens were 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.
The infection, which beyond diarrhea can cause fatigue, weight loss, stomach cramps, vomiting, muscle aches and low-grade fever, can be treated 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.
Fore more stories from ABC News click here.