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Molecular detection of Cyclospora cayetanensis in human stool specimens using UNEX-based DNA extraction and real-time PCR

  • Yvonne Qvarnstrom (a1), Theresa Benedict (a1), Paula L. Marcet (a1), Ryan E. Wiegand (a1), Barbara L. Herwaldt (a1) and Alexandre J. da Silva (a2)...


Cyclospora cayetanensis is a coccidian parasite associated with diarrheal illness. In the USA, foodborne outbreaks of cyclosporiasis have been documented almost every year since the mid-1990s. The typical approach used to identify this parasite in human stools is an examination of acid-fast-stained smears under bright-field microscopy. UV fluorescence microscopy of wet mounts is more sensitive and specific than acid-fast staining but requires a fluorescence microscope with a special filter not commonly available in diagnostic laboratories. In this study, we evaluated a new DNA extraction method based on the Universal Nucleic Acid Extraction (UNEX) buffer and compared the performances of four published real-time polymerase chain reaction (PCR) assays for the specific detection of C. cayetanensis in stool. The UNEX-based method had an improved capability to recover DNA from oocysts compared with the FastDNA stool extraction method. The best-performing real-time PCR assay was a C. cayetanensis-specific TaqMan PCR that targets the 18S ribosomal RNA gene. This new testing algorithm should be useful for detection of C. cayetanensis in human stool samples.


Corresponding author

Author for correspondence: Yvonne Qvarnstrom, E-mail:


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Molecular detection of Cyclospora cayetanensis in human stool specimens using UNEX-based DNA extraction and real-time PCR

  • Yvonne Qvarnstrom (a1), Theresa Benedict (a1), Paula L. Marcet (a1), Ryan E. Wiegand (a1), Barbara L. Herwaldt (a1) and Alexandre J. da Silva (a2)...


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