By Suzanne Le Mignot

(CBS) — It’s a parasite that has some incredibly troubling symptoms: Cramps, fatigue and diarrhea that just won’t go away.

The cyclosporiasis outbreak has happened in 15 states, including Illinois. Right now, two of those states, Nebraska and Iowa, have linked the illness to bagged lettuce, although it’s not known what brand. CBS 2’s Suzanne Le Mignot talked to local health experts about this powerful stomach bug.

Dr. Terry Mason, the Chief Operating Officer of the Cook County Department of Public Health, says there’s a very good way to make sure you don’t come in contact with the parasite found in human feces.

“All of us who have fruits and vegetables, should wash our fruits and vegetables before well we eat them,” said Dr. Mason.

The symptoms of cyclosporiasis are far from pleasant.

“You could have diarrhea for up to a month,” said Dr. Mason.

Mason says it’s very important to call your doctor to make sure the cyclospora parasite is not the cause of your illness.

“First, they should make certain they get a stool sample, so that if this particular parasite is the cause, it can be identified,” said Dr. Mason.

There have been four cases in Illinois, including Lake County in the Chicago area.

Health officials are linking it’s latest outbreak to a bagged salad mix. So far, they won’t name the brand or where it’s made.

“All of these 374 individuals will be interviewed and we will go through a very detailed food history as to what they consumed prior to the infection and we will then trace back the source of those food items,” said Dr. Michael Vernon of the Cook County Department Of Public Health.

The parasite can be treated with an inexpensive antibiotic called Bactrim. That’s why it’s very important to call your doctor if you start having any of the symptoms, associated with this parasite.

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