(Corrects headline to stomach bug instead of stomach virus)
July 25 (Reuters) - At least 285 people in 11 states have been sickened by a parasitic infection commonly linked to fresh produce, and the exact cause of the outbreak has yet to be pinpointed, the U.S. Centers for Disease Control and Prevention said on Thursday.
Most of the cyclospora infections have been clustered in the Midwest, with 138 cases reported in Iowa and 70 in neighboring Nebraska. The remainder have been identified in Texas, Georgia, Wisconsin, Connecticut, Illinois, Kansas, Minnesota, New Jersey and Ohio.
The cause of the illness has not yet been identified, but the parasite is most commonly found in fresh produce, including fruits, vegetables and herbs, grown in tropical and subtropical regions, according to Dr. Barbara Herwaldt, a medical epidemiologist at the CDC.
"Because no food item has been implicated to date we're not yet sure the cases in the various states are related," she said. "Though it's quite likely that the cases in the Midwest might be."
At least 18 people in three states have required hospitalization from the cyclospora parasite, which causes an intestinal infection called cyclosporiasis.
Cyclosporiasis is caused by ingesting food or water containing a one-celled parasite that is too small to be detected without a microscope. Symptoms include watery diarrhea, vomiting and body aches.
The symptoms usually manifest within several days of eating the contaminated food, and include diarrhea, cramps, nausea and fatigue. If not treated, the illness may last from a few days to a month or longer and patients have been known to relapse, the CDC said.
The first cases were reported in Iowa in late June, with the majority of the illnesses logged in early July. The CDC has not released the age range of those infected, but said it was working closely with the U.S. Food and Drug Administration and state officials to gather more information.
"We are carefully monitoring cases that are coming to our attention now to see if there's any evidence the outbreak is ongoing," Herwaldt said. "We don't know if it is and we are following it very closely."
As a precaution, she encouraged people to thoroughly wash produce before it is eaten to minimize the chance of infection. The CDC also recommends that anyone with cyclosporiasis-like symptoms seek medical treatment and ask to be tested for the parasite.
"The good news is that the infection is easily treatable with readily available antibiotics," Herwaldt said.
Most people with healthy immune systems recover from the infection without treatment. Older people and those with weakened immune systems might be at higher risk for prolonged illness. (Reporting by Victoria Cavaliere; Editing by Barbara Goldberg and Maureen Bavdek)