What type of organism is Cyclospora?

Cyclospora is a Protozoan Parasite

Cyclospora cayetanensis is a protozoan parasite that causes intestinal infection in humans and is characterized by watery diarrhea, abdominal symptoms, and potential for prolonged illness. 1

Classification and Biology

Cyclospora belongs to the coccidian class of protozoan parasites. Key biological characteristics include:

• Single-celled organism that produces oocysts which are excreted in feces
• Oocysts measure 8-10 microns in diameter and appear as non-refractile double-walled spheres 2
• Oocysts are not infectious when first excreted and require time (days to weeks) to sporulate in the environment 3
• Due to this requirement for sporulation, direct person-to-person transmission is unlikely 1, 3

Clinical Presentation

Cyclospora infection (cyclosporiasis) typically presents with:

• Watery diarrhea (primary symptom)
• Loss of appetite and weight loss
• Abdominal bloating and cramping
• Increased flatus
• Nausea and fatigue
• Low-grade fever
• Potential for relapses and prolonged illness lasting weeks to months if untreated 1

The clinical presentation can be particularly severe in:

• Immunocompromised individuals, especially those with HIV/AIDS 1
• Travelers to endemic areas 1
• Children in endemic regions 4

Diagnosis

Diagnosis of Cyclospora infection requires specific laboratory testing:

• Demonstration of Cyclospora oocysts in stool specimens through:

  • Morphologic criteria (microscopic examination)
  • Demonstration of sporulation
  • Detection of Cyclospora DNA by polymerase chain reaction (PCR) 1

• Standard ova and parasite testing may miss Cyclospora, so clinicians should specifically request Cyclospora testing when suspected 1

• Oocysts can be identified by:

  • Modified acid-fast stain (appear variably red)
  • Flotation in Sheather's sucrose solution
  • Autofluorescence properties 2, 5

Epidemiology and Transmission

Cyclospora has a distinct epidemiological pattern:

• Globally distributed but with higher prevalence in tropical and subtropical regions
• Marked seasonality in outbreaks and cases 3, 2
• Transmission occurs through:
  • Contaminated water
  • Contaminated fresh produce (particularly imported fruits and vegetables)
  • Soil contact in endemic areas 4
• Major cause of foodborne outbreaks in developed countries 3
• Important cause of traveler's diarrhea 1, 4

Treatment

The recommended treatment for Cyclospora infection is:

• Trimethoprim-sulfamethoxazole (TMP-SMZ), which is the only proven effective antibiotic 6
• Alternative options for sulfa-allergic patients include ciprofloxacin 500 mg twice daily for 7 days 1
• Supportive care with fluid and electrolyte replacement 6

Prevention

Prevention strategies include:

• Improved environmental sanitation in endemic areas
• Health education about proper food and water handling
• Careful washing of fruits and vegetables, particularly imported produce
• Safe water practices when traveling to endemic regions 4

Special Considerations

• Testing for Cyclospora should be considered in:

  • Persistent diarrhea (lasting >14 days) 1
  • Travelers returning from endemic areas 1
  • Immunocompromised patients with diarrhea 1
  • Outbreaks of diarrheal illness linked to food or water sources 1

• Cyclospora infection can be particularly severe and chronic in immunocompromised patients, especially those with HIV/AIDS, requiring prompt diagnosis and treatment 1, 3