Several cases of food poisoning that occurred in Pennsylvania earlier this year represent the first time infection with the parasite Cyclospora cayetanensis (cyclosporiasis) has been associated with snow peas, according to the Centers for Disease Control and Prevention.

Between June and July, public health officials were informed of several cases of cyclosporiasis among residents, staff, and volunteers associated with a residential facility. CDC investigators examined stool samples from several patients and confirmed it was cyclosporiasis, caused by C. cayetanensis.

The findings appear in the Morbidity and Mortality Weekly Report.

A total of 40 laboratory-confirmed and 56 probable cases of cyclosporiasis were identified. The investigators found that everyone who got sick had attended at least one of five special events catered by the facility. This led them to look for a food item that was served at all of these events, but not at other events-only a pasta salad fulfilled this requirement.

Examination of the salad revealed that only one ingredient-snow peas-was used in all the batches served at the events, was taken from one container, and was not served at other meals outside of the events.

The investigators were unable to directly implicate the snow peas because they were discarded after the last event and, therefore, could not be tested for evidence of the presence of C. cayetanesis.

Still, the circumstantial evidence strongly implicated the peas as the source of the outbreak. The US Food and Drug Administration later became involved and traced the peas to an exporter in Guatemala.

SOURCE: Morbidity and Mortality Weekly Report, September 24, 2004.