At least 285 people in 11 U.S. states appear to have contracted Cyclospora cayetanensis infections, the CDC said Thursday, but investigators remain baffled as to how.
According to a statement posted on the agency's website, no common features of the infections have been identified.
"No food items have been implicated to date, but public health authorities are pursuing all leads," the agency said, noting that Cyclospora is generally a foodborne pathogen.
"Previous outbreak investigations have implicated various types of fresh produce. It is not yet clear whether the cases from all of the states are part of the same outbreak. No common events (e.g., social gatherings) have been identified among the case patients."
Most of the infections have been reported in Iowa (138 cases), Nebraska (70), and Texas (66). Other states that have reported infections to the CDC include Connecticut, New Jersey, Georgia, Ohio, Wisconsin, Minnesota, Illinois, and Kansas, each reporting one to three cases.
Officials in Illinois and Kansas told the CDC that their Cyclospora cases (one each) appeared to have originated in other unidentified states.
The CDC itself has confirmed five cases in its own laboratory tests, one by telediagnosis using electronically transmitted micrographs of suspected oocysts. The agency urged other laboratories to confirm infections via telediagnosis.
Cyclospora cayetanensis, a monocellular parasite, is transmitted through the feces of infected individuals, the CDC said. The most notable symptoms are watery diarrhea and explosive bowel movements, but may also include other gastrointestinal complaints as well as fever and flu-like symptoms. Infection may be asymptomatic, the agency noted.
Diagnosis is confirmed by identifying Cyclospora oocysts in stool samples. The CDC-recommended treatment is the trimethoprim-sulfamethoxazole antibiotic combination.