AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Background

Cyclospora cayetanensis is a coccidian parasite that infects the GI tract of both immunocompetent and immunocompromised hosts. This organism was first described in human feces in 1979. Since the advent of the acquired immunodeficiency syndrome (AIDS) epidemic, C cayetanensis has been increasingly recognized as an enteric pathogen.¹

Cyclospora species are ubiquitous and infect various animals, including vipers, moles, rodents, and myriapods. Humans are the only known hosts of C cayetanensis. The first known outbreak of cyclosporiasis in the United States occurred in 1990 in a Chicago hospital's physicians' dormitory and was attributed to an infected water source. In 1996-97, US epidemics of cyclosporiasis were attributed to infected Guatemalan raspberries,^{2, 3} basil, and mesclun lettuce.^{4, 5, 6, 7} An outbreak resulted from exposure to contaminated berries at a social function in Ontario, Canada in 1999. More recent outbreaks have been associated with imported Thai basil⁸ and snow peas in a cluster of infections in Pennsylvania in 2004.^{9, 10} Otherwise, only sporadic cases, primarily involving travelers, have been documented.

Pathophysiology

Cyclospora species are variably acid-fast, round-to-ovoid organisms that measure 8-10 µm in diameter. Cyclospora species exogenously sporulate and have 2 sporocysts per oocyst. Transmission follows ingestion of oocysts in fecally contaminated water or produce. Direct person-to-person transmission is considered unlikely because the oocysts are not infectious when excreted; the oocysts undergo sporulation outside the human host before becoming infective. The median incubation period is 1 week, during which time the organism invades enterocytes of the small intestine.

Disease manifests as protracted and relapsing gastroenteritis. Cyclospora species are characterized by an anterior polar complex that allows penetration into host cells, but the life cycle of the parasite and the mechanisms by which it interacts with human host target cells to cause disease are poorly understood.

Frequency

United States

The frequency of cyclosporiasis is unknown.

International

Most fecal isolates have been obtained from residents of developing countries or from travelers returning from these regions. Cyclosporiasis is endemic in Haiti, Nepal, and Peru, with a strong seasonal predominance during rainy spring and summer months. Cyclosporiasis has also been reported in travelers returning from Mexico, Southeast Asia, Puerto Rico, Indonesia,¹¹ Morocco, Pakistan, and India.

Mortality/Morbidity

Death is exceptionally rare. Very little morbidity results from this infection, except in persons with underlying immunosuppression, in whom chronic diarrhea can develop.

Race

No racial predilection has been reported.

Sex

Cyclosporiasis equally affects both sexes.

Age

Persons of all ages can be affected, although cyclosporiasis primarily affects children in developing countries where the disease is endemic.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

History

Diarrhea is the hallmark of infection. Onset is abrupt, 1-14 days after exposure to a contaminated source. The diarrhea is described as profuse, malodorous, and watery and can cause dehydration and weight loss. Diarrhea may be associated with 1 or more nonspecific symptoms, including intermittent crampy abdominal pain, nausea, vomiting, low-grade fever, malaise, myalgias, anorexia, bloating, flatulence, and/or profound fatigue. These symptoms are indistinguishable from those of Isospora and Cryptosporidium infections.

• In an immunocompromised host, onset is more insidious, and the condition becomes chronic; symptoms and shedding of oocysts continue indefinitely. Biliary disease with right upper quadrant pain, increased alkaline phosphatase, and thickened gallbladder on ultrasound findings has been reported in an immunocompromised host infected with Cyclospora.
• In an immunocompetent host, diarrhea can persist for 7 days to several weeks, with a waxing and waning course.

Physical

Physical examination findings are unremarkable, other than signs of dehydration or, in an immunocompromised host, biliary disease.

Causes

Causes of cyclosporiasis include consumption of infected water or produce or exposure to the organism during travel to countries where it is endemic. Immunosuppression is a risk factor for chronic cyclosporiasis in endemic areas or among travelers to these areas.

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Other Problems to be Considered

Microspora infections

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Lab Studies

• Microscopic examination of fecal specimens with acid-fast staining
• • Diagnosis is based on the microscopic detection of oocysts in fecal specimens. Oocysts are round and resemble those of Cryptosporidium, but they are twice the size (8-10 µm). They are autofluorescent, appearing neon blue when examined with ultraviolet fluorescence microscopy. This property is not specific for Cyclospora species, however, and wanes as the specimen ages.
  • Stain Cyclospora species using modified Ziehl-Neelsen or Kinyoun acid-fast stains. These species are not visualized by Gram, Giemsa, silver, or hematoxylin-eosin staining.
• Stool testing for ova and parasites does not typically include testing for Cyclospora species; most laboratory workers are inexperienced at identifying the oocysts.
• No serologic assays are currently available to detect antibodies to Cyclospora species.
• Polymerase chain reaction tests for detection of Cyclospora DNA in stool specimens are now commercially available (by calling 800-637-0370) and may become the test of choice for making the diagnosis.

Procedures

• Small-bowel biopsy reveals pathologic changes, including blunting and atrophy of villi, acute and chronic inflammation, and hyperplasia of crypts. Severity of the histopathologic findings correlates with the severity of clinical symptoms, including malabsorption.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical Care

Cyclospora infection appears to be self-limited in an immunocompetent host, lasting several days to 2 weeks. The only supportive care typically needed is the replenishment of fluids and electrolytes with juices, water, and caffeine-free soda. Occasionally, the infection can persist for 3-5 weeks, necessitating oral rehydration therapy, parenteral rehydration therapy, or both. Infection in an immunocompromised host or in a child may require parenteral rehydration.

Consultations

For prolonged or severe cases, consultation with infectious diseases specialists, gastroenterologists, or both may help.

Diet

Typical dietary measures for gastroenteritis are appropriate.

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Trimethoprim-sulfamethoxazole (TMP-SMZ) has proven effective in managing Cyclospora infections in immunocompetent and immunocompromised hosts.¹² TMP-SMZ administration can reduce shedding of oocysts to 1.3 days (from 9 d) and stops diarrhea within 2 days.

An immunocompromised host requires oral antibiotic therapy for longer periods, followed by prophylaxis to prevent recurrence. One study has indicated that if the patient is allergic to or does not tolerate sulfa-containing medications, ciprofloxacin is an alternative treatment. Treatment with pyrimethamine and nitazoxanide is also being studied.

Drug Category: Antibiotics

These agents are used to treat infection. The combination product containing trimethoprim and sulfamethoxazole is considered the DOC for managing cyclosporiasis.

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Deterrence/Prevention

• As with other types of travelers' diarrhea, cyclosporiasis is easily preventable when traveling by avoiding untreated water and unpeeled fruits and vegetables, all of which can be contaminated.
• When caring for hospitalized patients infected with Cyclospora species, institute enteric precautions with thorough handwashing after each episode of patient contact.

Prognosis

• As this infection is self-limited in the immunocompetent host, full recovery is expected.
• With treatment and prophylaxis to prevent relapses, infection in the immunocompromised host can generally be adequately controlled.

Patient Education

• Discuss proper precautions needed when traveling in endemic regions to prevent this and all other fecal-oral infections.

MISCELLANEOUS

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• Failure to consider the diagnosis because identification of the oocysts may not occur during routine screening for stool pathogens

Special Concerns

• Report cases of cyclosporiasis to the health department.

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

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Article Last Updated: Feb 4, 2008