CYCLOSPORA
Section snippets
HISTORICAL NOTES
Cyclosporan organisms were first described by Eimer in 1870, and the genus Cyclospora was named by Schneider in 1881.30, 40 Subsequently, oocysts ranging in size from 12 to 36 by 6 to 22 μm and designated as members of various Cyclospora species have been detected in the intestines of snakes, myriapods, and rodents.40 Ashford provided the first description of human-associated cyclosporan oocysts, based on detection in stool specimens collected in 1977 and 1978, from three individuals living in
BIOLOGY
Cyclospora is a genus in the phylum Apicomplexa; thus the parasite is related to four other coccidian pathogens of humans: Cryptosporidium, Isospora, Toxoplasma, and Sarcocystis. In common with other apicomplexans, Cyclospora sporozoites have an apical complex composed of a polar ring, conoid, rhoptries, and other coccidian structures, including micronemes. The Cyclospora oocysts that have been detected in humans with intestinal disease are spherical and measure 8 to 10 μm in diameter; they are
EPIDEMIOLOGY
Infection with Cyclospora has been reported worldwide.* Before 1996, much of what was known about the epidemiology of Cyclospora was learned through studies conducted in Nepal, Peru, and Haiti26, 27, 40, 41, 43, 44, 47, 50; most documented North American cases of cyclosporiasis were in overseas travelers, and only three small US outbreaks had been reported.6, 28, 29 Large outbreaks of
CLINICAL MANIFESTATIONS OF DISEASE
Patients infected with Cyclospora typically have diarrhea, profound fatigue, anorexia, weight loss, abdominal bloating or gas, abdominal cramps, and nausea. Diarrhea is watery, without blood or inflammatory cells, and it often occurs in a cyclical pattern, sometimes alternating with constipation. Fever, chills, headache, and vomiting are less common. A flu-like prodrome with myalgias and arthralgias may precede diarrhea onset. The incubation period for Cyclospora infection averages 1 week but
HISTOPATHOLOGY AND PATHOGENESIS
Light and electron microscopic examination of distal duodenal and jejunal tissue biopsy specimens have provided evidence that human-associated Cyclospora is an intracellular organism that parasitizes the enterocytes of the upper small bowel.4, 16, 54 Asexual parasitic forms have been found in a supranuclear position within intracytoplasmic (parasitophorous) vacuoles. Inflammatory cell infiltrates in the lamina propria have also been described. Connor et al found inflammatory changes, villous
DIAGNOSIS
The diagnosis of Cyclospora infection is based on microscopic demonstration of oocysts in fecal specimens, duodenal or jejunal aspirates, or in biopsy specimens. Reports of missed and false-positive diagnoses9, 20 attest to the difficulties encountered in the laboratory detection of this parasite. Most experienced laboratory technologists detect the organism on their initial microscopic examination of wet mounts of fresh, unpreserved stool concentrates. Oocysts appear as nonrefractile spheres,
TREATMENT
Trimethoprim-sulfamethoxazole (TMP-SMX) is the treatment of choice for Cyclospora infection.25, 33, 44 In a placebo-controlled trial in Nepal, Hoge and Shlim et al showed that TMP-SMX (160/800 mg) taken twice daily for 7 days was statistically significantly better than placebo for Cyclospora.25 It is noteworthy that cyclosporiasis seems to have emerged in Nepal at a time when, due to growing resistance, quinolones replaced TMP-SMX for the treatment of bacterial enteritis. For HIV–infected
THE FUTURE
Cyclospora is a newly recognized coccidian parasite that is transmitted by contaminated water and food to immunocompetent and immunocompromised humans. The recent outbreaks of cyclosporiasis in the United States have heightened our awareness of the changing epidemiology of foodborne disease in the United States.14, 24, 42 Despite advances in our understanding of the biology and epidemiology of this organism, many questions remain unanswered. Further studies are needed to determine the infective
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Cited by (37)
Human cyclosporiasis
2019, The Lancet Infectious DiseasesCitation Excerpt :Prevention and control can be assisted by killing or removing oocysts from water or fresh foods. Since oocysts of Cyclospora are resistant to many disinfectants136 used in traditional water-treatment plants and are difficult to remove from water,130,137,138 physical treatments (eg, membrane filtration), ultraviolet disinfection, or managed aquifer recharge are possible approaches for their removal.138 Although sodium dichloroisocyanurate solution reduces the viability and infectivity of parasites including Cyclospora,139 chlorine as sodium hypochlorite is the most widely used disinfectant by industrial producers of fresh produce (raw vegetables and fruits), because it is inexpensive and easy to use.
Cyclospora cayetanensis
2013, Microbiology of Waterborne Diseases: Microbiological Aspects and Risks: Second EditionEpidemiology of Cyclospora cayetanensis: A review focusing in endemic areas
2010, Acta TropicaCitation Excerpt :Oocysts cannot be induced to sporulate after freezing at −18 °C for 24 h and after heating at 60 °C for 1 h (Sterling and Ortega, 1999). They are resistant to many disinfectants, including chlorination at levels used in water treatment (Rabold et al., 1994; Soave et al., 1998), but they are very sensitive to desiccation; oocyst wall ruptures after 15 min (Long et al., 1991). The oocysts require time, moisture and moderate temperature to become infective.
Foodborne protozoan parasites
2005, International Journal of Food MicrobiologyDetection of Cyclospora cayetanensis in travellers returning from the tropics and subtropics using microscopy and real-time PCR
2003, International Journal of Medical MicrobiologySequence variability in the first internal transcribed spacer region within and among Cyclospora species is consistent with polyparasitism
2001, International Journal for Parasitology
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