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Outbreaks of Cyclosporiasis -- United States, 1997

In April and May 1997, CDC received reports of seven event-associated clusters of cases of cyclosporiasis from five states (California, Florida, Nevada, New York, and Texas). Approximately 80 cases of infection with human-associated Cyclospora, a recently characterized coccidian parasite (1), have been laboratory-confirmed. State and local health departments, CDC, and the Food and Drug Administration are conducting investigations to identify the vehicles of infection.

Both foodborne and waterborne outbreaks of cyclosporiasis have previously been reported in the United States during spring and summer months (2-4). In 1996, a total of 978 laboratory-confirmed cases of cyclosporiasis in the United States and Canada were reported in association with a widespread foodborne outbreak (3). The average incubation period of cyclosporiasis is 1 week. Illness can be protracted (from days to weeks) with frequent, watery stools and other gastrointestinal symptoms; symptoms may remit and relapse. Health-care providers should consider Cyclospora infection in persons with prolonged diarrheal illness and specifically request laboratory testing for this parasite (5,6), which is not routinely performed by most laboratories.

Cyclosporiasis can be treated with a 7-day course of oral trimethoprim (TMP)-sulfamethoxazole (SMX) (for adults, 160 mg TMP plus 800 mg SMX twice daily; for children, 5 mg/kg TMP plus 25 mg/kg SMX twice daily) (7). Treatment regimens for patients who cannot tolerate sulfa drugs have not yet been identified.

Health departments that identify cases of cyclosporiasis should contact CDC's Division of Parasitic Diseases, National Center for Infectious Diseases, telephone (770) 488-7760.

Reported by: State and local health departments. Office of Regulatory Affairs, and Center for Food Safety and Applied Nutrition, Food and Drug Administration. Div of Parasitic Diseases, National Center for Infectious Diseases, CDC.


  1. Ortega YR, Sterling CR, Gilman RH, Cama VA, Daz F. Cyclospora species -- a new protozoan pathogen of humans. N Engl J Med 1993;328:1308-12.

  2. CDC. Update: outbreaks of Cyclospora cayetanensis infection -- United States and Canada, 1996. MMWR 1996;45:611-2.

  3. 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 (in press).

  4. Huang P, Weber JT, Sosin DM, et al. The first reported outbreak of diarrheal illness associated with Cyclospora in the United States. Ann Intern Med 1995;123:409-14.

  5. Soave R. Cyclospora: an overview. Clin Infect Dis 1996;23:429-37.

  6. Garcia LS, Bruckner DA. Diagnostic medical parasitology. 3rd ed. Washington, DC: American Society for Microbiology, 1997:66-9.

  7. Hoge CW, Shlim DR, Ghimire M, et al. Placebo-controlled trial of co-trimoxazole for Cyclospora infections among travellers and foreign residents in Nepal. Lancet 1995;345:691-3.

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