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Cyclospora cayetanensis is an emerging protozoan parasite capable of causing a protracted diarrheal illness in both immunocompromised and immunocompetent individuals. Ingestion of fresh produce and water sources contaminated with mature sporulated oocysts results in acquisition of cyclosporiasis. Currently, no animal model exists for the study of this pathogenic parasite and the only confirmed reservoir host for C. cayetanensis in nature is humans. Previously, Cyclospora-like oocysts had been detected by microscopy in several animals including non-human primates. However, their phylogenetic relationship to C. cayetanensis remained uncertain due to the limited availability of molecular techniques to differentiate and speciate these isolates. In the present study, we examined a series of fecal isolates obtained from dogs, chickens, and monkeys collected between May and September 2002 from several geographic regions of Nepal. All samples were examined by microscopy and a polymerase chain reaction (PCR) for the presence of C. cayetanensis. Both microscopic and conventional PCR/restriction fragment length polymorphism (RFLP) analysis demonstrated the presence of Cyclospora sp. in the fecal samples of two dogs, one chicken, and one monkey. Application of a species-specific multiplex PCR assay confirmed the presence of both Eimeria sp. and C. cayetanensis in the positive chicken sample and only C. cayetanensis in the dog and monkey samples. However, in the absence of tissue analysis, the assignment of these animals as a natural reservoir host for C. cayetanensis remains to be determined.
Received October 6, 2003. Accepted for publication April 14, 2004.
Authors addresses: Dan-My T. Chu, Division of Microbiological Studies, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD 20740. Jeevan B. Sherchand, Tribhuvan University Teaching Hospital, Department of Microbiology-Parasitology/Infectious and Tropical Diseases Research Center, Kathmandu, Nepal. John H. Cross, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814-4799. Palmer A. Orlandi, Center for Food Safety and Applied Nutrition/OARSA/Division of Virulence Assessment, U.S. Food and Drug Administration, MOD 1 Research Facility, Room 3603 (HFS-025), 8301 Muirkirk Road, Laurel, MD 20708, E-mail: porlande{at}cfsan.fda.gov.
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