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Original Article
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Volume 328:1308-1312 May 6, 1993 Number 18
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Cyclospora Species -- A New Protozoan Pathogen of Humans
Ynes R. Ortega, Charles R. Sterling, Robert H. Gilman, Vitaliano A. Cama, and Fernando Diaz

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ABSTRACT

Background Organisms referred to as "cyanobacterium-like bodies" have now been identified worldwide in the feces of both immunocompetent and immunocompromised patients with diarrhea. Organisms with a similar appearance have been isolated from Peruvian patients since 1985. From 1988 to 1991 we studied prospectively two cohorts of infants and young children infected with this organism. We now attempt to identify it.

Methods Fecal samples were collected weekly from the children and examined with the use of acid-fast staining and staining with a monoclonal antibody specific for cryptosporidium. Stools positive for cyanobacterium-like bodies were preserved in potassium dichromate and exposed to conditions allowing coccidian sporulation and excystation. Both unsporulated and sporulated oocysts were fixed by freeze-substitution techniques and then examined by electron microscopy.

Results Organisms isolated from the feces of Peruvian patients and two patients from the United States were identified as belonging to the coccidian genus cyclospora, after sporulation and excystation of the oocysts according to standard techniques. Complete sporulation occurred within 5 to 13 days in oocysts maintained in potassium dichromate at 25 or 32 °C. Complete excystation resulted in the liberation of two sporozoites from the two sporocysts within each oocyst (cryptosporidia have four naked sporozoites within each oocyst). The presence of organelles characteristic of coccidian organisms was confirmed by electron microscopy.

Conclusions We have identified organisms of the genus cyclospora that are remarkably similar to cryptosporidia in their morphologic features and the diarrheal disease that they produce in humans. The complete life cycle and epidemiology of this new protozoan parasite remain to be described.


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From the Department of Veterinary Science, University of Arizona, Tucson (Y.R.O., C.R.S., V.A.C.); the Department of International Health, Johns Hopkins University, Baltimore (R.H.G.); and the Departamento de Parasitologia, Universidad Peruana Cayetano Heredia, and the Asociacion Benefica PRISMA, both in Lima, Peru (R.H.G., F.D.).

Address reprint requests to Dr. Sterling at the Department of Veterinary Science, University of Arizona, Bldg. 90, Rm. 201, Tucson, AZ 85721.

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Related Letters:

Cyanobacterium-Like Cyclospora Species
Hoge C. W., Shlim D. R., Echeverria P., Heyworth M. F., Sterling C. R.
Extract | Full Text  
N Engl J Med 1993; 329:1504-1505, Nov 11, 1993. Correspondence

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