Cyclospora Diarrheal Illness Spread by Contaminated Raspberries


Synopsis: Coccidian intestinal protozoa are increasingly recognized as causes of foodborne illnesses in healthy persons as well as immunocompromised persons.

Source: Herwaldt BL, et al. An outbreak in 1996 of cyclosporiasis associated with imported raspberries. N Engl J Med 1997;336:1548-1556.

From cases of cyclosporiasis reported to the Centers for Disease Control and Prevention, retrospective, cohort studies were conducted of foodborne illness associated with events such as luncheons. A total of 1465 cases of cyclosporiasis, mostly in adults, were reported by 20 states, the District of Columbia, and two Canadian provinces from May 1996 to August 1996.

Approximately one-half of the cases were associated with 55 public meals in which raspberries from Guatemala were served. The mode of contamination of the raspberries was not identified.


Cyclospora cayetanensis, previously called cyanobacterium-like body, is a coccidian parasite similar to but larger than Cryptosporidium parvum. Illnesses caused by the spore-forming intestinal protozoa-C, cayetanensis, C. parvum, and Isospora belli have many features in common. These protozoa cause diarrheal illness in healthy persons but have been recognized primarily because of the severe intestinal injury and prolonged watery diarrhea in persons with immune dysfunction, including persons with AIDS. Another group of protozoa, the microsporidia, includes Enterocytozoon bieneusi and Septata intestinalis that are intestinal pathogens reported to cause similar diarrheal disease in patients with AIDS but not in healthy persons. These organisms cause intracellular infection of the enterocyte and are transmitted either by stool from person to person or through contaminated water or food. The average incubation period is one week. The most common symptom in healthy persons is mild-to-moderate, self-limited diarrhea; as many as 80-90% of infections in otherwise healthy persons are asymptomatic. Moderate Cyclospora illness is characterized by a median of six stools per day, with a median duration of 10 days (range, 3-25). The duration of diarrhea is characteristically longer for cyclosporiasis than the other intestinal protozoan illnesses. Associated symptoms frequently include: fatigue; abdominal bloating or gas; abdominal cramps or pain; nausea; muscle, joint, or body aches; fever; chills; headache; and weight loss. Vomiting may occur. Bloody stools are uncommon. Diagnosis is by laboratory visualization of spores or oocysts in the stool—usually, this must be specifically requested rather than by simply indicating "stool for O & P."

Following fecal excretion, the oocysts do not sporulate and remain infectious for days to weeks. Cyclosporiasis and isosporiasis can be effectively treated with trimethoprim-sulfamethoxazole for seven days.

Until 1996, most cases of cyclosporiasis in North America occurred in overseas travelers. Despite voluntary control measures in 1996 by the berry industry in Guatemala, there have been 21 additional clusters of cyclosporiasis from April 1997 to June 11, 1997, reported in the United States (California, Florida, Maryland, Nebraska, Nevada, New York, Rhode Island, and Texas) and Canada (Ontario) with 140 laboratory-confirmed and 340 clinically defined cases.1 These outbreaks have also been linked epidemiologically to Guatemalan raspberries.

On May 30, 1997, the Guatemalan government voluntarily suspended exports of fresh raspberries to the United States. Outbreaks caused by these pathogens may become more frequent because of the increasingly international source of fresh produce to the United States. Fresh produce should always be washed before it is eaten, but this may not completely prevent transmission. Produce such as raspberries are characterized by crevices that preclude effective rinsing away of contaminating microorganisms. In recent outbreaks, raspberries had been rinsed in 10 (71%) of the 14 events for which such information was available. Physicians should consider protozoan infection in persons with prolonged diarrhea, especially in the context of a local cluster of illness.


1. Centers for Disease Control and Prevention. Update: Outbreaks of cyclosporiasis—United States and Canada, 1997. MMWR Morb Mortal Wkly Rep 1997;23:521-523.