Cyclospora cayetanensis: Watch what you eat!

 Introduction: Cyclospora cayetanensis is an intestinal protozoan that infects humans. As of now, humans are the only known hosts, but chimpanzees and other similar primates may also be parasitized [3]. It is single celled organism that spreads to humans that have comsumed food or water contaminated with feces containing the oocyst. C. cayetanensis causes the disease Cyclospora, which infects the small intestine of humans. It is found mainly in tropical and subtropical regions. People living in developing countries are at the highest risk [3]. 

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Symbiont Description: Classification for Cyclospora cayetanensis was controversial for many years because it was often known as a Cyanobacteria-like body or a Coccidian-like body. Finally it was defined as intestinal coccidian protozoa, in the genus Cyclospora [4]. Sporulated oocytes are the infective stage and appear spherical with a thick double wall about 8-10 μm in size [4]. For the oocytes to become infectious they need an environment with moderate temperatures (68-70°F) in combination with moderate rainfall. Oocytes are resistance to adverse conditions and can survive for long periods of time as long as moisture is present. The sporulation process can take one to several weeks [3]. Each sporulated oocyte is single celled and contains two sporocytes, which contain two sporozoites each. The sporozoites are what infect the hosts [2]. They then undergo asexual multiplication and also sexual development into the mature oocystes, which are expelled through the feces [1].

Host: The parasite is considered holoxenous because it only has one host, which is the human. That is also its definitive host because it reaches sexual maturity in the human [1].

Life Cycle: An unsporulated oocyte is excreted from a human through its feces. In a favorable environment C. cayetanensis will take few days to a few weeks for sporulation to reach an infective state. The sporulated oocycte can be transmitted by fresh produce or water. Once ingested by humans the oocysts encyst in the gastrointestinal tract [1]. The sporozoites exit from the oocyst and penetrate the epithelial cells along the small intestine, usually preferring the jejunum. Here they undergo asexual fission to form meronts, which contain multiple merozoites. The merozoites penetrate new cells and form gametes. The macrogamete (female) and the microgamete (male) mate form an oocyst. The un-spoulated oocyst is then released through the feces and the cycle repeats [2].

Add capthttp://www.cdc.gov/parasites/cyclosporiasis/biology.htmlion

Ecology: Human infection causes the disease Cyclospora. Becoming infected and then actually becoming sick takes about one week. It causes watery diarrhea that is also accompanied with many flu like symptoms. If gone untreated symptoms can last from a few days to many months. Cyclospora is treated with the antibiotic trimenthoprim-sulfamethoxazole [1]. The disease can be widespread because of the transportation of food from country to country. There have been outbreaks in the U.S. caused by fresh raspberries, snow peas, and mesclun lettuce. The only known prevention is to avoid contact with contaminated food is to avoid food from unsafe sources [3].

An example of difference in social status can be seen here:

The encounter filter is open in developing countries where the parasite can take advantage of poor sanitation systems. The lower status means lower resource quality and high risk of contamination. Developing countries in tropical or subtropical regions have an increased risk of being infected. They also export produce that may be contaminated to many other different parts of the world. An aggregated distribution can be seen here, and it can also be linked to social status. Lack of knowledge in sanitation and cleaning can lead to a higher infection rate.

[1]"CDC - Cyclosporiasis - General Information - Cyclosporiasis FAQs." Centers for Disease Control and Prevention. Usa.gov, 2 Nov. 2010. Web. 09 Feb. 2012. http://www.cdc.gov/parasites/cyclosporiasis/gen_info/faqs.html

[2]Duluol. "Cyclospora Cayetanensis." Kansas State University. 31 Oct. 2001. Web. 09 Feb. 2012. <http://www.k-state.edu/parasitology/cyclospora/cyclospora.html>.

[3]Sigua, Gerald. "Preventing Foodborne Illness: Cyclospora Cayetanensis1." University of Florida IFAS Extension. Sept. 2005. Web. 9 Feb. 2012. <http://edis.ifas.ufl.edu/fs130>.

[4]Stefano, Lagana. "Atlante Dei Protozoi Intestinali Umani - Sezione COCCICI Identificazione 
Microscopica Di Giovanni Swierczynski E Bruno Milanesi." Atlante Dei Protozoi Intestinali Umani, Identificazione Microscopica Di Giovanni Swierczynski E Bruno Milanesi. Web. 09 Feb. 2012. <http://www.atlas-protozoa.com/Cyclospora_cayetanensis.php>.

[5] Combes, Claude. Parasitism: The Ecology and Evolution of Intimate Interactions. Chicago: 2001. 257.