Cyclospora cayetanensis, a coccidian protozoan, causes a diarrheal illness first described in humans in 1979.
- Worldwide distribution, with areas of endemic infection (Nepal, Peru, Haiti, Guatemala, Indonesia)
- People living in endemic areas have a shorter illness or may be asymptomatic carriers.
- Cyclospora can be an opportunistic infection in human immunodeficiency virus patients.
- In the United States, infection occurs primarily in spring and summer.
- In the United States and Canada, cases are associated with consumption of imported fresh produce.
- Fresh produce, especially raspberries, cilantro, and salad mixes, should be washed thoroughly before being eaten, although this still may not entirely eliminate the risk of transmission.
- Avoid consumption of waste water and, in endemic areas, avoid consumption of tap water.
- Infected patients excrete noninfectious unsporulated oocysts in their stool.
- Sporulation then occurs days to weeks after release into the environment.
- Ingestion of sporulated oocysts occurs and sporozoites are released that invade the intestinal epithelial cells.
- Sporozoites develop into trophozoites, which undergo schizogony and form merozoites.
- Merozoites may develop into macro- or microgametes, which become fertilized, resulting in oocysts.
- Entire life cycle is completed in the host.
- Incubation period is between 2 and 14 days, with an average of 7 days.
- Outbreaks have been associated with the consumption of raspberries, mesclun (young salad greens), salad mixes, cilantro, and basil.
- Infection occurs through the consumption of contaminated food and water.
- Transmission does not occur through person-to-person spread.
- Low-grade fever is common.
- Clinical prodrome
- Acute onset of diarrhea is typical, but a flulike prodrome may occur.
- Nature of the diarrhea
- Profuse, nonbloody, watery diarrhea that may be foul smelling
- Can alternate with constipation
- Other symptoms experienced:
- Abdominal cramping
- Foods that have been consumed in the past 2 weeks
- Illness has been attributed to contaminated raspberries, water, mesclun, salad mix, cilantro, and basil.
- Due to profuse diarrhea
- Signs of dehydration (tachycardia, dry mucous membranes, sunken eyes, poor skin turgor, and weight loss) may be present.
- Outbreaks are associated with contaminated water sources (municipal pools).
- Person-to-person transmission may occur.
- Clinically indistinguishable from Cyclospora
- Cystoisospora belli
- Outbreaks are associated with food and water.
- Clinically indistinguishable from Cyclospora, although fever may be more common
- Outbreaks are associated with contaminated water sources.
- Chronic diarrhea occurs in immunocompromised patients, especially HIV patients.
- Fever is uncommon.
- Giardia lamblia
- Community epidemics are associated primarily with contaminated water sources.
- Person-to-person transmission may occur and has led to outbreaks in day care centers.
- Clinical presentation may vary from occasional acute watery diarrhea to a severe, protracted diarrheal illness.
- Viral gastroenteritis
- Bacterial gastroenteritis
- Clostridium difficile
- Vibrio cholerae and non-cholerae Vibrio species
- Escherichia coli (especially toxin-producing strains)
- Shigella species
- Salmonella species
- Yersinia enterocolitica
- Campylobacter species
Diagnostic Tests and Interpretation
- Ova and parasites with modified acid-fast staining
- Identification of Cyclospora, Cystoisospora, and Cryptosporidium
- Three samples are preferable due to intermittent shedding.
- Ova and parasites: identify common protozoans including Giardia
- Cryptosporidium and Giardia antigen test: immunoassay with high sensitivity and specificity
- Electron microscopy of stool: gold standard for diagnosing microsporidia
- Bacterial stool cultures: identify common bacterial pathogens
- Stool for C. difficile PCR: identify a common cause of diarrhea
- Gastrointestinal multiplex nucleic acid testing: simultaneous qualitative detection and identification of multiple viral, parasitic, and bacterial nucleic acids in stool specimens from individuals with gastroenteritis (some panels include Cyclospora)
- Electrolytes, blood urea nitrogen, creatinine: may be helpful in some cases to determine extent of dehydration
- Immunocompetent patient: trimethoprim-sulfamethoxazole (5 mg/kg) IV/PO twice a day for 7 to 10 days
- HIV patient: trimethoprim-sulfamethoxazole 3 times a day for 10 days and then prophylactic dosing 3 times per week to prevent relapse
- Ciprofloxacin or nitazoxanide for 7 days may be alternatives in patients with sulfa allergy.
- Based on severity of dehydration, treatment with IV fluids may be indicated.
Moderate to severe dehydration should warrant admission.
- Infected patients need to be observed closely for dehydration.
- Relapse may occur in HIV patients, so close follow-up is essential.
- Most cases are self-limited.
- Diarrhea may last up to 3 months in untreated patients who acquired the parasite in a foreign country where Cyclospora is endemic.
- In U.S. outbreaks, the average duration of diarrhea ranged from 10 to 24 days.
- Relapses may occur in untreated patients.
- Patients with HIV have more severe and prolonged diarrhea, which may recur.
- Dehydration and weight loss are the most common complications.
- Severe, prolonged diarrhea may lead to dehydration.
- Malabsorption of d-xylose and excretion of fecal fat occurs, leading to weight loss.
- May cause ascending biliary tract disease in AIDS patients
- Rare associated complications
- Guillain-Barré syndrome
- Reactive arthritis
- Centers for Disease Control and Prevention. Outbreaks of cyclosporiasis—United States, June–August 2013. MMWR Morb Mortal Wkly Rep. 2013;62(43):862. [PMID:24172881]
- Herwaldt BL. Cyclospora cayetanensis: a review, focusing on the outbreaks of cyclosporiasis in the 1990s. Clin Infect Dis. 2000;31(4):1040–1057. [PMID:11049789]
- Legua P, Seas C. Cystoisospora and Cyclospora. Curr Opin Infect Dis. 2013;26(5):479–483. [PMID:23982239]
- Ortega YR, Sanchez R. Update on Cyclospora cayetanensis, a food-borne and waterborne parasite. Clin Microbiol Rev. 2010;23(1):218–234. [PMID:20065331]
240372001 Cyclosporiasis (disorder)
- Q: Does routine ova and parasites testing detect Cyclospora?
- A: Rarely. Therefore, modified acid-fast staining must be done to improve the laboratory’s ability to detect the oocysts.
- Q: Can person-to-person transmission occur in Cyclospora illness?
- A: No. It takes days to weeks for oocysts to sporulate and become infectious.
- Q: Can animals/pets be affected by this same pathogen?
- A: Humans are the only natural hosts of Cyclospora infection.
Jessica R. Newman, DO
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