Update: Outbreaks of Cyclosporiasis -- United States, 1997

During April and May 1997, CDC received reports of clusters of cases of cyclosporiasis in the United States (1). This report describes the preliminary findings of an investigation of an outbreak in New York and summarizes the findings from on-going investigations in other states. New York

On May 15, the Westchester County Health Department was notified of two laboratory-confirmed cases of cyclosporiasis and other cases of diarrheal illness among persons who attended a wedding reception on April 20 at a private residence in the county. A case of cyclosporiasis was defined as onset of diarrhea (three or more loose stools during a 24-hour period) 1-14 days after the reception. Of the 183 persons who attended the reception, 154 (84%) were interviewed, and 140 were included in this analysis (persons who had loose stools that did not meet the case definition were excluded). Of the 140 persons, 20 (14%) had illness that met the case definition; four cases were laboratory confirmed. The median incubation period was 8 days (range: 3-11 days), and for 19 persons, the duration of diarrheal illness was greater than or equal to 3 days.

Eating raspberries was the exposure most strongly associated with risk for illness in univariate analysis and was the only exposure significantly associated with risk for illness in multivariate logistic regression analysis. Sixteen (36%) of the 45 persons who ate raspberries became ill, compared with three (4%) of the 85 persons who did not eat raspberries (univariate relative risk=10.1; 95% confidence interval=3.1-32.8). The raspberries had not been washed.

Other Investigations

CDC has received reports of eight event-associated (e.g., reception) clusters of cases of cyclosporiasis from five states (California, Florida, Nevada, New York {includes Westchester County}, and Texas) and a report of cases among persons who, during March 29-April 5, had been on a cruise ship that left from Florida. The most recent of the eight events occurred on May 8. Approximately 90 event-associated cases of infection have been laboratory confirmed.

Fresh berries were served at six of the eight events. Raspberries were included in mixtures of various types of berries at four events, were served separately from other berries at one event (the event in Westchester County), and were the only type of berry served at one event (in Nevada). Eating the food items that included raspberries was significantly associated with risk for illness for four events, including the two events at which raspberries could be distinguished from other berries (Westchester County and Nevada events); for one of the other two events, all 10 persons ate the berry mixture that was served and became ill. At one event where the implicated food item included a mixture of berries, the source of the raspberries was Guatemala; preliminary traceback data for the other events at which raspberries were served indicate that both Guatemala and Chile may be sources (i.e., each country was the source of at least one of the shipments of raspberries that could have been used).

State and local health departments, CDC, and the Food and Drug Administration (FDA) are continuing the investigations to identify the vehicles of infection, to trace the sources of implicated foods, and to determine whether transmission is ongoing.

Reported by: G Jacquette, MD, F Guido, MPA, J Jacobs, Westchester County Dept of Health, Hawthorne; P Smith, MD, State Epidemiologist, New York State Dept of Health. Other state and local health depts. D Adler, San Francisco, California. Office of Regulatory Affairs, and Center for Food Safety and Applied Nutrition, Food and Drug Administration. Foodborne and Diarrheal Diseases Br and Childhood and Respiratory Diseases Br, Div of Bacterial and Mycotic Diseases, and Div of Parasitic Diseases, National Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: The preliminary findings of the investigations described in this report suggest that raspberries imported from Guatemala and possibly from Chile were the likely vehicle of infection for some of the outbreaks of cyclosporiasis during April and May. In the spring and summer of 1996, an outbreak of cyclosporiasis in the United States and Canada was linked to eating raspberries imported from Guatemala (2). However, the mode of contamination of the implicated raspberries in that outbreak was not determined -- in part because the methods for testing produce and other environmental samples for Cyclospora are insensitive.

Produce should always be thoroughly washed before it is eaten. This practice should decrease, but may not eliminate, the risk for transmission of Cyclospora. Because raspberries are fragile and replete with crevices (3), even thorough washing may not eliminate contamination of the fruit. State and local health departments, CDC, and FDA are evaluating the findings from the investigations to determine the need for additional public health measures.

Health-care providers should consider Cyclospora infection in persons with prolonged diarrheal illness and specifically request laboratory testing for this parasite. Cases should be reported to local and state health departments; health departments that identify cases of cyclosporiasis should contact CDC's Division of Parasitic Diseases, National Center for Infectious Diseases, telephone (770) 488-7760.

References

1. CDC. Outbreaks of cyclosporiasis -- United States, 1997. MMWR 1997;46:451-2.

2. Herwaldt BL, Ackers M-L, Cyclospora Working Group. An outbreak in 1996 of cyclosporiasis associated with imported raspberries. N Engl J Med 1997;336:1548-56.

3. Robbins JA, Sjulin TM. Scanning electron microscope analysis of drupelet morphology of red raspberry and related Rubus genotypes. J Am Soc Horticult Sci 1988;113:474-80.

   
   

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