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Cyclospora cayetanensis.jpg
Cyclospora cayetanensis
Classification and external resources
Specialty infectious disease
ICD-10 A07.8
ICD-9-CM 007.5
DiseasesDB 32228
eMedicine [1]/topic527.htm ped [1]/527
Patient UK Cyclosporiasis
MeSH D021866
[edit on Wikidata]

Cyclosporiasis is a disease caused by infection with Cyclospora cayetanensis, a pathogenic protozoan transmitted by feces or feces-contaminated food and water.[2] Outbreaks have been reported due to contaminated fruits and vegetables. It is not spread from person to person, but can be a hazard for travelers as a cause of diarrhea.

Mode of infection

When an oocyst of Cyclospora cayetanensis enters the small intestine, it invades the mucosa, where it incubates for about one week. After incubation, the infected person begins to experience severe watery diarrhea, bloating, fever, stomach cramps, and muscle aches. The parasite particularly affects the jejunum of the small intestine. Of nine patients in Nepal who were diagnosed with this illness, all had inflammation of the lamina propria along with an increase of plasma in the lamina propria. Of this sample, oocysts were observed in the duodenal aspirates.[3] Oocysts are often present in the environment as a result of using contaminated water or human feces as fertilizer. Cyclosporiasis primarily affects humans and primates.

Diagnosis and treatment

Diagnosis can be difficult due to the lack of recognizable oocysts in the feces. PCR-based DNA tests and acid-fast staining can help with identification. The infection is often treated with trimethaprim-sulfamethaxozol, also known as Bactrim or co-trimoxazole, because traditional anti-protozoal drugs are not sufficient. To prevent transmission, food should be cooked thoroughly and drinking water from streams should be avoided while outdoors.

Vaccine research

There is no vaccine to control Cyclospora infection in humans at present, but one is available for reduction of fetal losses in sheep.


The first recorded cases of Cyclospora in humans were as recent as 1977, 1978, and 1979. They were reported by Ashford, a British parasitologist who discovered 3 cases while working in Papua New Guinea. Ashford found that the parasite had very late sporulation, from 8–11 days, making the illness difficult to diagnose. When examining feces, the unsporulated oocysts can easily be mistaken for fungal spores, and thus can be easily overlooked.[4] During the first cases discovered in the early 1980s, Cyclospora was identified as one of the most important opportunistic infections among AIDS patients.[1] Although it was initially thought that Cyclospora was confined to tropical and subtropical regions of the world, occurrences of Cyclosporiasis are becoming more frequent in North America. According to the Centers for Disease Control and Prevention, a U.S. government public health agency, there have been 11 documented Cyclospora outbreaks in the U.S. and Canada since the 1990s. The CDC also recorded 1,110 laboratory-confirmed sporadic instances of Cyclosporiasis.[5] Between June and August 2013, multiple independent outbreaks of the disease in the U.S. sickened at least 631 people across 25 states.[6][7] Investigations later identified a bagged salad mixture as the cause of the outbreak in Iowa and Nebraska.[8]

In 2015, the CDC was notified of 546 ill persons with confirmed Cyclospora infection across 31 states. Cluster investigations in Texas, where the greatest number of infections was reported, suspected contaminated cilantro as the culprit.[9] Epidemiology of Cyclospora cayetanensis in Nepal: It is critical to note that Cyclospora cayetanensis infections have been well reported in Nepal with their defined epidemiology. After it was reported to occur in expatriates living in Kathmandu, it has been diagnosed in human and animal stool samples and vegetables around the country. Tirth Raj Ghimire, Purna Nath Mishra and Jeevan Bahadur Sherchan collected massive stool samples from different health care centers and washing samples of vegetables, water samples of sewage, pond, well, municipal taps, and rivers within Kathmandu valley from 2002 to 2004 [10]. They found Cyclospora in radish, cauliflowers, cabbage, mustard leaves, and sewage and river water. This first epidemiologic study determined the seasonal characters of Cyclospora outbreaks in Nepal in several nurseries and schools, feasts and religious ceremonies, for example, during the rainy seasons from May to September suggesting seasonal outbreaks [11]. In the same year, Tirth Raj Ghimire and Purna Nath Mishra reported a Cyclospora infected patient with low hemoglobin status and suggested that this coccidian might be involved in reducing hemoglobin due to lack of immune system [12]. In 2006, their groups published a paper about the role of Cyclospora in HIV/AIDS patients and non-HIV/non-AIDS patients from Kathmandu valley[13].

In 2007, Indian reasearchers published a case report study in which there was an association of Cyclospora infection with Bell's palsy. This was important because in addition to other extra-intestinal reports, Cyclospora might be involved in either reversible neuronal damage or other unknown mechanisms to lead to Guillan Barr Syndrome or Bell's palsy. This is the first reported case of Bell’s palsy following chronic Cyclospora infection [14].

In 2008, the same groups published a report about the epidemiology of Cyclospora cayetanensis in HIV/AIDS patients in Kathmandu, Nepal. [15]. They examined the samples of soil, river water, sewage water, chicken stool, dog stool, stool in street, and others and found to be positive for Cyclospora. They also evaluated several factors as risk for Cyclospora in AIDS patients.[16]. In 2010, a report of Cyclospora transmission via swimming in the Kathmandu valley was published in the Journal of Institute of Medicine.[17]. In this paper, it was shown that openly defecated stool samples of human around the swimmer's living quarters and near the swimming pool were positive for Cyclospora. Although Cyclospora was found in the environmental stool samples as well as swimmer in this study, they did not report positive case of Cyclospora in dog stool, bird stool, cattle dung, vegetable samples, and water samples near the patient's habitat and swimming pool. Thus, water of swimming pool contaminated via environmental pollution with Cyclospora might have caused the diarrheal infections as this parasite can resist chlorination in water. In addition, the case person had accidentally drunk the pool water during swimming [18].


  1. ^ a b Ortega, Ynes. "Update on Cyclospora cayetanensis, a Food-Borne and Waterborne Parasite". American Society for microbiology. Clinical Microbiology Reviews. Retrieved April 17, 2017. 
  2. ^ Talaro, Kathleen P., and Arthur Talaro. Foundations in Microbiology: Basic Principles. Dubuque, Iowa: McGraw-Hill, 2002.
  3. ^
  4. ^ Strausbaugh, Larry (1 October 2000). "Cyclospora cayetanensis: A Review, Focusing on the Outbreaks of Cyclosporiasis in the 1990s". Infectious Disease Society of America. 31 (4): 1040. doi:10.1086/314051. Retrieved 17 April 2017. 
  5. ^ "Surveillance for Laboratory-Confirmed Sporadic Cases of Cyclosporiasis --- United States, 1997--2008". 
  6. ^ "Case Count Maps - Outbreak Investigations 2013 - Cyclosporiasis - CDC". 
  7. ^ "CDC: 425 cases of cyclospora infection identified across 16 states". 5 August 2013. 
  8. ^ Iowa Cyclospora Outbreak 2013 /Outbreak Update 7.31.13, Iowa State Department of Public Health. Downloaded 6 Aug 2013.
  9. ^
  10. ^ Ghimire TR, Mishra PN, Sherchand JB. The seasonal outbreaks of Cyclospora and Cryptosporidium in Kathmandu, Nepal. Journal of Nepal Health Research Council. 2005; 3(1): 39–48.
  11. ^ Ghimire TR, Mishra PN, Sherchand JB. The seasonal outbreaks of Cyclospora and Cryptosporidium in Kathmandu, Nepal. Journal of Nepal Health Research Council. 2005; 3(1): 39–48.
  12. ^ Ghimire TR, Mishra PN. Intestinal parasites and Haemoglobin concentration in the people of two different areas of Nepal. Journal of Nepal Health Research Council. 2005; 3(2): 1–7.
  13. ^ Ghimire TR, Mishra PN. Intestinal parasites in the Human Immunodeficiency Virus Infected Patients in Kathmandu, Nepal. The Nepalese Journal of Zoology. 2006; 1(1): 9–19.
  14. ^ Ghimire TR, Mishra PN, Sherchand JB, Ghimire LV: Bell’s Palsy and Cyclosporiasis: Causal or Coincidence? Nepal Journal of Neuroscience 4:86- 88, 2007.
  15. ^ Ghimire TR, Mishra PN, Sherchan JB. Epidemiology of Cyclospora cayetanensis and other intestinal parasites in the HIV infected patients in Kathmandu, Nepal. Journal of Nepal Health Research Council. 2008; 6(12): 28–37.
  16. ^ Ghimire TR, Mishra PN, Sherchan JB. Epidemiology of Cyclospora cayetanensis and other intestinal parasites in the HIV infected patients in Kathmandu, Nepal. Journal of Nepal Health Research Council. 2008; 6(12): 28–37.
  17. ^
  18. ^ Ghimire TR, Ghimire LV, Shahu RK, Mishra PN. Cryptosporidium and Cyclospora infection transmission by swimming. Journal of Institute of Medicine. 2010; 32 (1): 43–45.

External links

  • Cyclosporiasis at Centers for Disease Control & Prevention
  • Cyclospora Infection at
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