Cyclosporiasis Clinical Overview and Resources

Cyclosporiasis (Cyclospora cayetanensis)

Cyclospora cayetanensis is a microscopic parasite that causes the diarrheal disease cyclosporiasis. Both the parasite and the disease are commonly known as “Cyclo.“ The parasite is spread by the fecal-oral route and is usually transmitted by contaminated food or water. Foodborne cases/outbreaks are possible and have been linked to various types of fresh produce including basil, cilantro, raspberries, mesclun lettuce and snow peas.

It is unlikely that Cyclospora is passed directly from person to person as the parasite requires approximately 1-2 weeks after being passed in a bowel movement to become infectious to another person. 

2010 CDC Case Definition

Tab/Accordion Items

An illness of variable severity caused by the protozoan parasite Cyclospora cayetanensis. The most common symptom is watery diarrhea. Other common symptoms include loss of appetite, weight loss, abdominal cramps/bloating, nausea, body aches, and fatigue. Vomiting and low-grade fever also may be noted.

Laboratory-confirmed cyclosporiasis shall be defined as the detection of Cyclospora organisms or DNA in stool, intestinal fluid/aspirate, or intestinal biopsy specimens.

Probable: a case that meets the clinical description and that is epidemiologically linked to a confirmed case. 

Confirmed: a case that meets the clinical description and at least one of the criteria for laboratory confirmation as described above. 

Cyclosporiasis Investigation Overview

The following guidelines provide a brief overview of the steps of a cyclosporiasis investigation.

For additional support, consult the NC Communicable Disease Branch at 919-733-3419. 

Critical Elements for NCEDSS

Document if high-risk (food worker, child care attendee/worker or health care worker)

Forms for Health Departments

Contact us to obtain the Cyclosporiasis Surveillance Case Report Form.

Basic Steps of a Cyclospora Investigation

Tab/Accordion Items

Clinical criteria are not required for the cyclosporiasis case definition. Laboratory evidence is sufficient to meet case definition. 

Onset of watery diarrhea, (which can be frequent and at times explosive) appetite loss, weight loss, stomach cramps/pain, bloating, increased gas, nausea, and fatigue. 

  • Vomiting, body aches, headache, fever, and other flu-like symptoms may also be noted 
  • Use information collected from medical records or speak with the case 
  • Some cases may be asymptomatic 
  • Epidemiologic linkages to similarly ill people and other risk factors 
  • If 2 or more cases are identified report as an outbreak 

  • The
    incubation period
    is usually 7 days (range, 2 days to more than 2 weeks)
  • The duration can be a few days to >30

  • Verify that case has been appropriately tested, (a cyclosporiasis test must be specifically ordered, it is not usually included in routine test panel) treated and isolated during the infectious period
  • Evaluate laboratory result to determine if requirements for case definitions are met.
  • Ensure reporting laboratory has forwarded the specimen to the SLPH for serotyping if it is an outbreak situation.
  • Interview the case and complete the Part 2 Form/risk history and clinical packages in NCEDSS.
  • Most people with cyclosporiasis infection recover without specific treatment

Direct person-to-person transmission is unlikely, as is transmission via ingestion of newly contaminated food or water, since the parasite requires approximately 1-2 weeks after being passed in a bowel movement to become infectious to another person  

If source of exposure is suspected to be restaurant-related, involve Environmental Health Specialist

  • There are no special control measures for those in high-risk settings other than returning after symptoms have resolved.
  • Parasites are not usually passed from one person to another.

High-risk contacts include:

  • Individuals at high risk for severe illness or complications
  • Health care workers
  • Child care workers
  • Food handlers

Resources: CDC - Cyclosporiasis

Symptomatic Contacts
  • Symptomatic contacts may be an indication of a possible outbreak. 
  • Refer to health care provider for appropriate testing and treatment.
  • Provide control measures.
Implement Control Measures
  • Exclude symptomatic individuals until symptoms have resolved.
  • Positive individuals who are no longer symptomatic may return to food service, health care and child care.
  • Exclude infected children from child care facilities until diarrhea resolves. 
Asymptomatic Cases
  • Environmental Health Specialist (EHS) should be consulted regarding return criteria for food employees

Notes about the Disease 

Cyclospora cayetanensis, the causative organism of cyclosporiasis, has been problematic on several fronts ever since the repetitive Guatemalan raspberry outbreaks began in the US in 1996. A major problem for the fresh produce industry has been devising an effective method for decontaminating fruits and vegetables potentially contaminated with this protozoan. Also, determination of the exact route of produce contamination remains to be satisfactorily resolved. Thirdly, to date, only humans have been confirmed as hosts for C. cayetanensis, but investigation into other possible hosts continues. 

Like cryptosporidiosis, cyclosporiasis is an “emerging” protozoan diarrheogenic infection that first became recognized as a human pathogen in the 1970s. It is endemic in a number of developing countries, and chlorine resistance is another feature C. cayetanensis shares with Cryptosporidium parvum. Although it is technically a fecal-oral agent, as documented by University of North Carolina School of Public Health investigators, C. cayetanensis leaves the body in a non-infectious (oocyst) stage and must undergo sporulation outside the human host before becoming infectious, a process that can take days to weeks.1

Laboratory methods for documentation of cyclosporiasis have improved since the mid-1990s but still depend basically on microscopic examination of preserved stool specimens.

Besides imported raspberries and other produce, water has been an occasional vehicle for transmission of C. cayetanensis. Fresh basil was the apparent source of infection for several Cabarrus County residents who dined at a Myrtle Beach, SC, restaurant in May 20052; a considerably larger outbreak traced to basil occurred in Florida concomitantly.3

Prevention of cyclosporiasis currently depends on avoiding food or water that might be fecally contaminated. At the very least, fruits and vegetables — including fresh herbs — should be washed under running potable water before consumption.

  • 1

    EM Alfano-Sobsey, et al., “Human Challenge Pilot Study with Cyclospora cayetanensis,” Emerging Infectious Diseases 10, no. 4 (2004): 726-8, www.cdc.gov/ncidod/EID/vol10no4/pdfs/03-0356.pdf

  • 2

    “Outbreak of Cyclosporiasis Among Patrons of a Mexican-Style Restaurant - Limestone County, Alabama, May-June 2023,” 
    MMWR Morb Mortal Wkly Rep. 2025 Apr 17;74(13):217-221, DOI: 10.15585/mmwr.mm7413a1

  • 3

    “Outbreak of cyclosporiasis in a U.S. Air Force training population, Joint Base San Antonio-Lackland, TX, 2018,” MSMR. 2019 Jun;26(6):14-17. https://pubmed.ncbi.nlm.nih.gov/31237763/

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This page was last modified on 07/28/2026