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Category: Clinical Microbiology
Cystoisospora, Cyclospora, and Sarcocystis*, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555817381/9781555817381.ch141-1.gif /docserver/preview/fulltext/10.1128/9781555817381/9781555817381.ch141-2.gifAbstract:
“Cystoisospora, Cyclospora, and Sarcocystis” provides an overview of the life cycles, pathogenesis, diagnosis, and treatment of these important parasites. These coccidial parasites have an environmentally resistant oocyst stage in their life cycles. They remain an important cause of diarrhea in patients in developing countries, and foodborne outbreaks still occur in developed countries. Humans are the only definitive hosts for Cystoisospora belli and Cyclospora cayetanensis and pass unsporulated oocysts in their stools. Sarcocystis requires two hosts. Humans are definitive hosts for S. hominis and S. suihominis and become infected after ingesting undercooked meat of bovids (cattle, buffalo) and pigs, respectively. Humans pass sporulated oocysts and sporocysts in their stools. Humans are also accidental intermediate hosts for one or more Sarcocystis species, and most cases are observed in Southeast Asia. Muscle sarcocysts are associated with fever and muscle pain. Diagnosis of Cystoisospora, Cyclospora, and Sarcocystis is based on microscopic examination of stool samples using acid-fast-stained slides or with UV microscopy. PCR-based methods of stool examination for oocysts have been developed. There are currently no serologic tests available to detect antibodies to these parasites and aid in their diagnosis. Combination antiretroviral therapy (cART) is associated with a better prognosis in AIDS patients, but clinical episodes still occur even in some patients on cART. Treatments for acute Cystoisospora and Cyclospora infections are available and effective. Apparent drug failures are most likely related to poor drug absorption or distribution rather than to true drug resistance.
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Line drawings of unsporulated and sporulated oocysts of Cyclospora cayetanensis (A and B) and Cystoisospora belli (C and D) and a sporulated oocyst (E) and sporocyst (F) of a Sarcocystis species from humans. Bar, 10 μm. doi:10.1128/9781555817381.ch141.f1
Line drawings of unsporulated and sporulated oocysts of Cyclospora cayetanensis (A and B) and Cystoisospora belli (C and D) and a sporulated oocyst (E) and sporocyst (F) of a Sarcocystis species from humans. Bar, 10 μm. doi:10.1128/9781555817381.ch141.f1
Modified Kinyoun’s acid-fast-stained smears demonstrating a Cystoisospora belli oocyst with a sporont (A), a C. belli oocyst with two sporoblasts (B), and a Cyclospora cayetanensis oocyst with a sporont (C). Bar, 1µm. doi:10.1128/9781555817381.ch142.f2
Modified Kinyoun’s acid-fast-stained smears demonstrating a Cystoisospora belli oocyst with a sporont (A), a C. belli oocyst with two sporoblasts (B), and a Cyclospora cayetanensis oocyst with a sporont (C). Bar, 1µm. doi:10.1128/9781555817381.ch142.f2
Sporocyst of a Sarcocystis species in a stool sample viewed using differential interference contrast microscopy (A) and autofluorescence using UV light (B). Bar, 10 μm. Courtesy of Alice E. Houk, Department of Biomedical Sciences and Pathobiology, Virginia Tech, Blacksburg, VA. doi:10.1128/9781555817381.ch141.f3
Sporocyst of a Sarcocystis species in a stool sample viewed using differential interference contrast microscopy (A) and autofluorescence using UV light (B). Bar, 10 μm. Courtesy of Alice E. Houk, Department of Biomedical Sciences and Pathobiology, Virginia Tech, Blacksburg, VA. doi:10.1128/9781555817381.ch141.f3
Hematoxylin and eosin-stained tissue section demonstrating several monozoic tissue cysts (arrows) of Cystoisospora belli. Note the thick wall that surrounds each single zoite. Bar, 10 μm. doi:10.1128/9781555817381.ch141.f4
Hematoxylin and eosin-stained tissue section demonstrating several monozoic tissue cysts (arrows) of Cystoisospora belli. Note the thick wall that surrounds each single zoite. Bar, 10 μm. doi:10.1128/9781555817381.ch141.f4
Sarcocyst (arrow) of a Sarcocystis species in a skeletal muscle biopsy specimen from a male Dutch patient obtained during an outbreak of muscular sarcocystosis ( 49 ) among visitors to Tioman Island off the east coast of Malaysia. A sarcocyst wall (arrowhead) surrounds hundreds of bradyzoites. Note the lack of inflammatory response. The patient’s traveling partner was also confirmed to be positive by muscle biopsy. Bar, 10 μm. Courtesy of Douglas H. Esposito and Clifton Drew, National Center for Emerging and Zoonotic Infectious Diseases, CDC, Atlanta, GA. doi:10.1128/9781555817381.ch141.f5
Sarcocyst (arrow) of a Sarcocystis species in a skeletal muscle biopsy specimen from a male Dutch patient obtained during an outbreak of muscular sarcocystosis ( 49 ) among visitors to Tioman Island off the east coast of Malaysia. A sarcocyst wall (arrowhead) surrounds hundreds of bradyzoites. Note the lack of inflammatory response. The patient’s traveling partner was also confirmed to be positive by muscle biopsy. Bar, 10 μm. Courtesy of Douglas H. Esposito and Clifton Drew, National Center for Emerging and Zoonotic Infectious Diseases, CDC, Atlanta, GA. doi:10.1128/9781555817381.ch141.f5
Structural data for Cystoisospora, Cyclospora, and Sarcocystis oocysts and sporocysts found in stool samples from humans
Structural data for Cystoisospora, Cyclospora, and Sarcocystis oocysts and sporocysts found in stool samples from humans