Cyclospora Infection Overview

Cyclospora

• A coccidian, spore-forming protozoan
• Oocysts are 8-10 µm in diameter
• Infection occurs through ingestion of sporulated oocysts in food or water
• Oocysts require weeks to months (1-2 weeks in optimal conditions) to sporulate outside humans and become infectious (human-to-human transmission is unlikely)
• Infectious dose of oocysts is unknown
• Asymptomatic carriers may excrete oocysts without being ill
• Natives of endemic areas may frequently be asymptomatic, but infectious
• Cyclospora is endemic in Haiti, Peru and Nepal where rainy-season outbreaks occur. Outside these areas, infections are usually travel-related

Cyclospora Background Infections

• 1996: 1,465 cases of cyclosporiasis in North America
  • 20 US States, 2 Canadian Provinces
• 1997: 1,600 cases in North America
  • Strawberries were implicated first before raspberries were identified as the major culprit
• Cyclospora infection was virtually unknown in North America before 1996
• In order to continue exporting products to the United States in 1996, Guatemalan farms required improvements in water quality, employee hygiene, and sanitary conditions
• Further outbreaks associated with raspberries occurred in April 1997, and the USA suspended Guatemalan raspberry importation in late May
• Outbreaks also linked to other foods, including mesclun (spring mix), fresh basil, and fresh snow peas

Cyclospora Outbreaks

• 1998: Over 300 people became ill from raspberries in Toronto, Ontano
• 1999: Several outbreaks of cyclosporiasis occurred, with Guatemalan blackberries being suspected as a source but never definitively proven in two outbreaks
• 2000: Multiple outbreaks occurred, and Guatemalan raspberries were linked as a source in two outbreaks

Cyclospora Contamination

• Contamination of berries remains unknown, but possibilities include:
  • Fecal contamination of water used for fruit irrigation or pest control
  • Contamination during storage or during the packing process
  • Insect or bird droppings contamination prior to picking

Cyclospora Health Effects

• Clinical features include watery diarrhea (yellow or khaki-green, without blood), lasting an average of 19-43 days, often explosive diarrhea, severe fatigue, anorexia, nausea, vomiting, abdominal bloating, weight loss, stomach cramps and in a small percentage, fever, chills, and a flu-like illness
• Symptoms may occur 1-11 days after exposure (average 1 week)
• Untreated cases in immuno-competent hosts may last 1-2 months or longer
• Reactive arthritis is sometimes seen after prolonged infections
• Ocular inflammation and sterile urethritis may also be observed

Cyclospora Resistance

• Low levels are sufficient to cause disease
• Extremely resistant to chlorine
• In endemic areas, boiling water or filtration is suggested

Cyclospora Diagnosis

• Diagnosis may be through detection of eggs in stool samples or duodenal aspirates.
• Oocysts autofluoresce a bright blue color under UV light (365nm)
• Acid-fast staining and detection of parasite DNA through PCR are also possible methods.