Widespread foodborne cyclosporiasis outbreaks present major challenges.

354 Letters To the Editor: The organism now named Cyclospora cayetanensis was first recognized as a cause of human illness in 1977. For several years, as its taxonomy was deliberated , it was referred to as " cyanobacterium-, or coccidia-like bodies " (CLBs), or considered to be blue-green algae. In 1993, C. cayetanensis was reported to be a protozoan parasite, a coccidian member of the family Eimeriidae. To be infectious, the spherical, chlorine-resistant oocyst (8µm to 10µm) found in the feces of infected persons must sporulate in the environment, a process that, depending on conditions, takes at least several days. Upon examination by ultraviolet microscopy, Cyclospora oocysts autofluo-resce and upon staining, they are variably acid-fast. The incubation period between infection and onset of symptoms averages approximately 1 week. Cyclospora infects the small intestine and usually causes watery diarrhea, with frequent stools. It can also cause loss of appetite, weight loss, stomach cramps, nausea, vomiting, fatigue, increased flatus, and low-grade fever. The duration of symptoms is often several weeks, and remitting courses spanning 1 to 2 months, with several relapses, have been reported. Cyclosporiasis is effectively treated with trimethoprim/sulfamethoxazole; however, therapy for patients who are sulfa-intolerant has not been identified. Before 1996, only three outbreaks of Cyclospora infection had been reported in the United States. However, between May 1 and mid-July 1996 almost 1,000 laboratory-confirmed cases were reported to the Centers for Disease Control and Prevention (CDC). A few hospitalizations (<20) were reported, but no Cyclospora-related deaths were confirmed. These infections occurred in at least 15 states and Canadian provinces and the District of Columbia. Investigations of approximately 50 event-related outbreaks of diarrheal illness due to C. cayetanensis, as well as case-control studies of sporadic, laboratory-confirmed cases by several states, now clearly implicate consumption of fresh raspberries. Complete, high confidence level trace-backs of raspberry shipments related to more than 25 of the events have indicated that the raspberries responsible were imported from Guatemala between early May and mid-June 1996. On June 17, 1996, CDC began hosting thrice-weekly conference calls to ensure close coordination among CDC, the U.S. Food and Drug Administration (FDA), and the many state and local health agencies investigating these widespread outbreaks and cases. The conference calls provided coordination in tracking and discussing this multifocal problem. In addition, on July 17, 1996, in Atlanta, CDC and FDA held a 1-day workshop entitled " cyclospora-1996, " which was attended by …