Basics
Description
Cyclospora cayetanensis, a coccidian protozoan, causes a diarrheal illness first described in humans in 1979.
General Prevention
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.
Epidemiology
- 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.
Pathophysiology
- 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.
Etiology
- 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.
Diagnosis
History
- Fever
- 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
- Fatigue
- Anorexia
- Flatulence
- Vomiting
- Foods that have been consumed in the past 2 weeks
- Illness has been attributed to contaminated raspberries, water, mesclun, salad mix, cilantro, and basil.
Physical Exam
Dehydration
- Due to profuse diarrhea, signs of dehydration (tachycardia, dry mucous membranes, sunken eyes, poor skin turgor, and weight loss) may be present.
Diagnostic Tests & Interpretation
Lab
- Ova and parasites with modified acid-fast staining
- Identification of Cyclospora, Isospora, and Cryptosporidium
- Three samples are preferable due to intermittent shedding.
- PCR testing is available from the CDC.
- 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 Clostridium difficile PCR: identify a common cause of diarrhea
- Electrolytes, blood urea nitrogen, creatinine: determine extent of dehydration
Differential Diagnosis
- Cryptosporidium
- Outbreaks are associated with contaminated water sources (municipal pools).
- Person-to-person transmission may occur.
- Clinically indistinguishable from Cyclospora
- Isospora belli
- Outbreaks are associated with food and water.
- Clinically indistinguishable from Cyclospora, although fever may be more common
- Microsporida
- 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
- C. difficile
- Vibrio cholerae and non-choleraeVibrio species
- Escherichia coli (especially toxin-producing strains)
- Shigella species
- Salmonella species
- Yersinia enterocolitica
- Campylobacter species
Treatment
Medication
- Immunocompetent patient: trimethoprim (5 mg/kg)-sulfamethoxazole IV/PO twice a day for 7-10 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.
Inpatient Considerations
Admission Criteria
Moderate to severe dehydration
Ongoing Care
Prognosis
- 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.
Complications
- 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-Barr © syndrome
- Reactive arthritis
Patient Monitoring
- Infected patients need to be observed closely for dehydration.
- Relapse may occur in HIV patients, so close follow-up is essential.
Additional Reading
- Centers for Disease Control and Prevention. Notes from the field: outbreaks of cyclosporiasis-United States, June-August 2013. MMWR Morb Mortal Wkly Rep. 2013;62(43):862. [View Abstract]
- Herwaldt BL. Cyclospora cayetanensis: a review, focusing on the outbreaks of cyclosporiasis in the 1990s. Clin Infect Dis. 2000;31(4):1040-1057. [View Abstract]
- Ortega YE, Sanchez R. Update on Cyclospora cayetanensis, a food-borne and waterborne parasite. Clin Microbiol Rev. 2010;23(1):218-234. [View Abstract]
Codes
ICD09
ICD10
SNOMED
- 240372001 Cyclosporiasis (disorder)
FAQ
- 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.