The CDC is investigating the source of an extensive outbreak of Cyclospora infection with 690 confirmed cases in 13 states and in four provinces of Canada with 37 confirmed cases.  The outbreak commenced in mid-May and is still in progress.  A difficulties in investigating the infection includes the prolonged incubation time, which may extend up to five weeks. 

It is possible to determine the presence of the causal organism Cyclospora cayetanensis in food or fecal samples but genetic typing has not been developed to facilitate correlation of isolates from patients with food products.  It is presumed that the vehicle of infection is bagged salad mixes under the Fresh Express brand.

 Environmental studies have demonstrated the presence of Cyclospora in an irrigation canal in Florida serving farms that have provided leafy greens packed by Fresh Express.  For subscribers unfamiliar with Cyclosporidia infection, a quick parallel is coccidiosis in poultry since the life cycles of the human and avian pathogens are essentially similar.