Epidemiology / Geography:
Cyclospora cayetanensis can be found worldwide, most commonly in Latin American, India, sub-Saharan Africa, and Southeast Asia. Reported cases have also been described in Canada, the United States, Europe, and the Caribbean due to global travel, rapid fresh food importing, and increased fresh food consumption.
The United States has witnessed several outbreaks since the mid-1990s. These have been traced to various types of imported fresh produce including contaminated raspberries, basil, snow peas, sugar snap peas, bagged salad mix, green onions, and cilantro. Although humans are the only known natural host, direct person-to-person transmission is not likely. Infections typically occur during rainy seasons; however, variable seasonal effects can be observed.
Predisposing Medical History:
Children 10-15 years old, elderly individuals, and immunocompromised hosts typically develop more severe clinical symptoms. Sex, race, or ethnicity has not been proven to have an impact on incidence.
Cyclospora cayetanensis is an obligate intracellular parasite that is highly resistant to disinfectants commonly used in food and water processing. Oocysts are passed in the feces and shed in a noninfective form, requiring several days before they become infectious. A low infectious dose (10-100 organisms) may be sufficient for infection. When contaminated food or water is ingested, the sporozoites exit the oocyst to infect the jejunum and duodenal epithelial cells. Replication occurs, and the oocysts are excreted back into the environment as unsporulated oocysts to mature (sporulate) outside in the host.
Signs / Symptoms:
- Typical – Nondysentery cyclical diarrhea, anorexia, nausea, flatulence, fatigue, weight loss, and low-grade fevers occur about 7 days following ingestion of the offending agent. Gastrointestinal symptoms may be preceded by a flu-like prodrome. If untreated, the illness may last more than a month in a cyclical, relapsing pattern. Milder disease with shorter duration or asymptomatic infections can occur if infected in endemic areas.
- Variants – Intermittent diarrhea and abdominal cramping may last weeks to months. Acalculous cholecystitis has been described in an HIV-infected patient. Reactive arthritis (formerly known as Reiter's syndrome) has also been reported.
A07.4 – Cyclosporiasis
240372001 – Cyclosporiasis
- Cystoisosporiasis (formerly isosporiasis) – Also causes diarrhea. Peripheral eosinophilia can be seen in half of patients. Modified acid-fast staining is also used. The key difference is the oocyst shape (thin walled, translucent, elongated) and size (20 microns).
- Cryptosporidiosis – Waterborne diarrheal illness, particularly in patients with AIDS; also seen on modified acid-fast staining. The key difference is the oocyst shape (ovoid to elliptical) and size (4-6 microns).
- Microsporidiosis – Gastrointestinal illness most often seen in HIV-infected patients. May also cause nodular cutaneous lesions. Also seen on modified acid-fast staining, but the darkly stained oocysts are only about 1 micron in size.