Maggie Fox NBC News

A company whose commercial bagged salad mixes are suspected of being the source of a large outbreak of parasitic food poisoning has suspended production and shipment of all its salad products from Mexico, federal health officials said Monday.

READ MORE | FDA names Taylor Farms as source in parasite outbreak

The Food and Drug Administration says Taylor Farms won't resume shipments without the agency's approval. About 535 people have been made sick by the cyclospora parasite.

"To date only the salad mix has been implicated in the outbreak of cyclosporiasis in Iowa and Nebraska," the FDA said in a statement. "This voluntary action goes beyond the implicated salad mix and includes iceberg lettuce, romaine lettuce, green leaf lettuce, red cabbage, green cabbage and carrots. The action of Taylor Farms de Mexico exemplifies the company's cooperation with federal and state officials throughout this ongoing, complicated investigation."

Bruce Taylor, CEO of the company, says he is confident its products are safe. "Our Mexico plant produces about 10 percent of our salad products for the US and it is pretty easy to temporarily shift production to our six domestic plants," he told NBC News by email. "We want to help with a thorough investigation by the FDA of our operation in Mexico to confirm confidence in our environment, our food safety systems and our operations."

READ MORE | Cases top 350 in parasite outbreak; source remains mystery

The FDA says cyclospora cases have been reported in 18 states plus New York City. "The restaurants in Iowa and Nebraska include Olive Garden and Red Lobster, both of which are owned by Darden Restaurants. FDA's investigation has not implicated consumer packages sold in grocery stores," the agency says.

"It is not yet clear whether the cases reported are all part of the same outbreak. The FDA is continuing its investigation and has not ruled out any possibilities.

Cyclospora cayetanensis is a one-celled parasite spread by fecal contamination of food or water. It takes about a week after it's passed out of the body to become infectious and so isn't usually passed from person to person, the Centers for Disease Control and Prevention says.

"Cyclospora infects the small intestine and usually causes watery diarrhea, with frequent, sometimes explosive, bowel movements," CDC says. "Other common symptoms include loss of appetite, weight loss, stomach cramps/pain, bloating, increased gas, nausea, and fatigue."

Cyclospora infections can be treated with antibiotics.