Cyclospora cayetanensis: Difference between revisions

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==Natural Reservoir==
==Natural Reservoir==
The only hosts C. cayentanensis uses are humans.<ref name=CDC>{{cite web | title = Cyclosporiasis | url = http://www.cdc.gov/parasites/cyclosporiasis/biology.html }}</ref>
The only hosts C. cayentanensis uses are humans.<ref name=CDC>{{cite web | title = Cyclosporiasis | url = http://www.cdc.gov/parasites/cyclosporiasis/biology.html }}</ref>
== Recognition ==
Due to its small size, intracellular habitat, and inability to properly uptake many histological stains, diagnosis of ''Cyclospora cayetanensis'' can be very difficult.  Four methods have thus far been established for positive diagnosis of the protozoan:  microscopic detection in stool samples of oocysts; recovering oocysts in intestinal fluid/small bowel biopsy specimens; demonstration of oocyst sporulation; and amplification by [[PCR]] of ''C. cayetanensis'' [[DNA]].  Since detection is so hard, one negative result should not discount the possibility of ''C. cayetanensis'':  tests involving fresh stool samples over the next few days should also be considered.
Except for PCR amplification, once a sample with suspected oocysts has been recovered, standard tests are followed to identify ''C. cayetanensis''.  These tests include [[Microscopy#Phase_Contrast_Optical_Microscopy|phase contrast microscopy]] to check for the spherical oocysts described earlier, modified acid-fast staining to check for variable stainability (all the way from pale to red), and [[autofluorescence]] with [[ultra violet|UV]] lights.  Obtaining these oocysts is usually the challenge, though recent studies show easier methods of obtaining them.  In a recent study on different techniques used in fecal exams to identify oocysts, it was demonstrated that centrifuging a sample of feces in a sucrose solution and then transferring a small amount to a slide was remarkably effective—both in oocysts found and relative ease of labor—in detecting ''C. cayetanensis'' oocysts:  indeed, the paper concluded that the total number of positive samples obtained was around 84%.
''C. cayetanensis'' has been confused with other protozoan infections in the past, the most often of which was ''Cryptosporidium parvum''.  There are several differences that can be noted between the two, however, to ensure proper diagnosis.  These differences include size difference — ''C. parvum'' is smaller; differing results from modified acid-fast staining — ''C. parvum'' has consistent red staining; and autofluorescence under UV light — ''C. cayetanensis'' does, ''C. parvum'' does not.


== Treatment ==
== Treatment ==

Revision as of 14:33, 18 September 2014

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: João André Alves Silva, M.D. [2]

Overview

Cyclospora cayetanensis is a protozoan that causes disease in humans, and perhaps other primates. It is sometimes referred to as the “yuppie disease” due to outbreaks in the United States from fecally-contaminated imported raspberries and was virtually unknown before about 1990, but has been on the rise since. The health risk associated with the disease is usually confined to adult foreigners visiting endemic regions and acquiring the infection: this is why C. cayetanensis has been labeled as causing “traveler’s diarrhea.” Given the recent rise of this protozoan menace, it is important to be able to characterize, recognize, and give proper treatment for C. cayetanensis.

This species was placed in the Cyclospora genus because of the spherical shape of its sporocysts. The species name refers to the Universidad Peruana Cayetano Heredia in Lima, Peru, where early epidemiological and taxonomic work was done.[3]

Taxonomy

Eukaryota; Alveolata; Apicomplexa; Conoidasida; Coccidia; Eucoccidiorida; Eimeriorina; Eimeriidae; Cyclospora[1]

Biology

Cyclospora cayetanensis is apicomplexan, cyst-forming coccidian protozoan, of the family of Eimeriidae, that causes a self-limiting diarrhea. Morphologically C. cayetanensis has spherical oocysts that are between 7.5 and 10 micrometers in diameter that also have a 50 nanometer thick bilayered wall with an outer threadlike coat that has been called a wrinkle by some researchers.[2][3][4]





Tropism

Natural Reservoir

The only hosts C. cayentanensis uses are humans.[2]

Treatment

Though the diarrhea caused by C. cayetanensis is self-limiting, relapses can and do occur. To date, the most effective drug for the treatment of the protozoan is a seven-day course of oral trimethoprim-sulfamethoxazole (TMP-SMX). Effects of the drug include significant decrease in the duration of oocyst excretion and cessation of diarrhea and stool samples negative for oocysts between two and three days. Relapse patients respond promptly to the therapy, and there has been talk of using TMP-SMX as a prophylaxis for HIV/AIDS patients.

Since infection occurs via fecally contaminated food and water in endemic environments, there are several simple solutions to suggest for the prevention of C. cayetanensis infections. The simplest one is to warn travelers not to visit regions where the protozoan is endemic (generally tropical and sub-tropical regions such as Peru, Brazil, and Haiti), especially when the disease is in its best season for spreading: such was the reason behind the first reported case of cyclosporiasis in Korea. This is not to say that natives of a region are completely free from possible infection: a middle-aged Turkish lawyer living in an urban area with water sanitized by the local government and with no travel history recently became Turkey’s first autochthonous case. This woman most likely received the infection from consuming some infected foodstuffs (possibly raspberries) that were not thoroughly washed before consumption. Thus, better health practices in the originating agricultural setting—such as ensuring produce is fully washed and kept away from human feces—and in the individual’s environment—taking an extra few seconds to wash that produce as well—would lead to a lower incidence of infection.



References

  • Ak, Mucide, Berrin Karaayak, Turan Kaya, Meral Turk, and Metin Turker. "Cyclosporiasis associated with diarrhoea in an immunocompetent patient in Turkey." Journal of Medical Microbiology 53 (2004): 255-251.
  • Belosevic, Miodrag, Yoshinobu Ishibashi, Masato Kawabata, Kenji Kimura, Shiba-Kumar Rai, Kaoru Takemasa, and Shoji Uga. "Comparison of three microscopic techniques for diagnosis of Cyclospora cayetanensis". FEMS Microbiology Letters 238 (2004): 263-266.
  • Gajadhar, Alvin A. and Mansfield, Linda S.; "Cyclospora cayetanensis, a food- and waterborne coccidian parasite." Veterinary Parasitology 126 (2004): 73-90.
  • Sohn, Woon-Mok and Jae-Ran Yu. "A case of human cyclosporiasis causing traveler's diarrhea after visiting Indonesia." Journal of Korean Medical Science 18 (2003): 738-741.
  1. "Cyclospora cayetanensis".
  2. 2.0 2.1 "Cyclosporiasis".
  3. Ortega YR, Sanchez R (2010). "Update on Cyclospora cayetanensis, a food-borne and waterborne parasite". Clin Microbiol Rev. 23 (1): 218–34. doi:10.1128/CMR.00026-09. PMC 2806662. PMID 20065331.
  4. Ortega YR, Gilman RH, Sterling CR (1994). "A new coccidian parasite (Apicomplexa: Eimeriidae) from humans". J Parasitol. 80 (4): 625–9. PMID 8064531.