THURSDAY, Aug. 1 (HealthDay News) -- The ongoing outbreak of stomach illness linked to the cyclospora parasite has now spread to 15 states and New York City, with 378 cases reported, according to the latest U.S. Centers for Disease Control and Prevention report issued Wednesday.
The source or sources of the nationwide outbreak has not yet been located, although health officials at two of the hardest-hit states, Iowa and Nebraska, say they have traced local outbreaks to an as-yet-unnamed salad mix.
In a posting on its website, the CDC said that it "will continue to work with federal, state, and local partners in the investigation to determine whether this conclusion applies to the increase in cases of cyclosporiasis in other states. It is not yet clear whether the cases from all of the states are part of the same outbreak."
Prior outbreaks of cyclospora infection have typically been caused by tainted produce, the agency noted.
While no one has died from cyclosporiasis, "at least 21 persons reportedly have been hospitalized in three states," the CDC said. Most people got sick between mid-June through early July.
Cases have now been reported from Arkansas, Connecticut, Florida, Georgia, Illinois, Iowa, Kansas, Minnesota, Missouri, Nebraska, New Jersey, New York City, New York State, Ohio, Texas and Wisconsin.
Cases of cyclosporiasis, which is caused by a single-celled parasite and can trigger diarrhea and stomach cramps, have been mounting through the month of July, said Dr. Monica Parise, chief of the parasitic diseases branch of the U.S. Centers for Disease Control and Prevention. The cyclospora parasite cannot be spread from person to person; it has to be ingested via contaminated water or foods such as fruit and vegetables.
"It can be pretty miserable, because it can give diarrhea that can last for days," Parise said.
Cyclospora is a tiny parasite but is devastatingly effective, added Dr. Bruce Hirsch, an attending physician in the division of infectious diseases at North Shore University Hospital in Manhasset, N.Y.
"You can ingest as few as 10 of these little critters and get sick," Hirsch said.
The first reported cases occurred in Iowa, which has been hardest hit with 143 people falling ill so far. The first cases came in late June, with more infections reported through July.
Other states reporting large numbers of infections are Nebraska, with 78 cases, and Texas, with 101 cases.
It takes about a week for people who are infected to become sick.
Dr. Thomas Frieden, CDC director, urged people who have suffered from diarrhea longer than a couple of days to be tested for cyclospora. Antibiotics can be used to treat severe cases of infection.
Earlier outbreaks of cyclospora have been traced back to fruits and vegetables imported from tropical regions like Latin America and Southeast Asia, where the parasite is common, Parise and Hirsch said.
"Our food supply system is large, complex and centralized. We get foods from all over the world, and they are packaged together and sent very, very quickly," Hirsch said. "I look at large outbreaks like this, and it makes me wonder if more locally grown foods would be safer."
People who want to avoid infection should thoroughly wash all their fruits and vegetables, Hirsch said. They also should wash cooking surfaces and utensils with hot, soapy water.
"For the most part, it's a miserable nuisance, but the concern I have as a doctor is for patients whose immune systems are weakened [and] have a real hard time with this infection," Hirsch said. He urged extra caution for people undergoing cancer treatment, recovering from an organ transplant or dealing with HIV infection.
For more information on cyclospora, visit the U.S. Centers for Disease Control and Prevention.