Practical Parasitology

Cyclospora cayetanensis

• Size of oocyst: 8 - 10 microns
• C. cayetanensis is a protozoan parasite of the small intestine causing symptoms normally associated with the flu accompanied by nausea, vomiting, and explosive diarrhea lasting up to three weeks in immunocompetent patients. (32)(33)
• Transmission is via the ingestion of contaminated food or water.
• In the 1996-97 cyclosporiasis outbreaks in North America, infection was the result of the ingestion of mature oocysts of C. cayetanensis from raspberries, pesto dishes and mesculin lettuce. An epidemiological study reveiled that contaminated water was the main vector of transmission in Guatemala.(35) The same study also showed children as being the most commonly infected.
• Associated with travel to tropical countries such as Mexico, Haiti and Central America.
• The oocysts stained with a modified acid fast Kinyoun stain appear red, pink, clear or colorless. Often they may resemble a wrinkled raisin with a granular interior or appear empty.
• They may at times resemble C. parvum however they are larger, and do not contain the typical sporozoites of C. parvum.
• It is highly recommended to measure all oocysts recovered from stool.(33)

The microphotographs below illustrate the diversity of their morphology.

Click on the image below to enlarge.

Life Cycle

Infection takes place after the ingestion of an infective oocyst. The amount of time required to become infective is dependent on environmental conditions such as heat and humidity.(32) One study conducted induced sporulation with potassium dichromate at 25^oC. A large population of the oocysts showed sporulation after 1 - 2 weeks.(37) Both a sexual and asexual cycle are involved with the entire life cycle taking place in a single host. Man appears to be the only host of C. cayetanensis.(37)(38)

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The material on this site is owned by Scientific Image and Consulting
David M. Raymondo
MLT, CLS(m)
Professional Affiliation: Gamma-Dynacare Medical Laboratories, Ottawa, Ontario, Canada
Gamma-Dynacare is a Division of the Dynacare Health Group