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Cryptosporidium hominis, along with Cryptosporidium parvum, is among the medically important Cryptosporidium species.^[1] It is an obligate parasite of humans that can colonize the gastrointestinal tract resulting in the gastroenteritis and diarrhea characteristic of cryptosporidiosis. Unlike C. parvum, which has a rather broad host range, C. hominis is almost exclusively a parasite of humans. As a result, C. hominis has a low zoonotic potential compared to C. parvum. It is spread through the fecal-oral route usually by drinking water contaminated with oocyst laden feces.^[2]

Characteristics

C. hominis shares many similar characteristics with C. parvum including identical oocyst morphology and life-cycle. As a result, C. hominis is most easily differentiated from C. parvum through genetic analysis at specific loci.^[3]^[4]

In The Netherlands, C. hominis is responsible for an autumnal spike in cases of cryptosporidiosis, though reasons for this spike remain unclear.^[5]

Life cycle

The life cycle of Cryptosporidium hominis is similar to that of others of the genus with infective sporozoites from ingested oocysts invading gut epithelium. From there, they undergo merogony and generate merozoites, which escape and can reinvade additional cells and form a secondary meront. The secondary meront then releases secondary merozoites which reinvade and undergo gametogony forming micro and macrogametocytes. The gametocytes can then fuse, forming a zygote, which starts the cycle again.

Treatment

Though symptoms in most immunocompetent persons will resolve without treatment, Nitazoxanide has been approved for treatment of diarrhea resulting from cryptosporidiosis. The effectiveness of Nitazoxanide in immunocompromised patients, however, is uncertain and current treatments revolve around boosting the host immune system to aid in symptom resolution.^[6] Current avenues for treatment include scanning the Cryptosporidium hominis genome for possible targets for vaccine development.^[7]

References

^ Leoni F, Amar C, Nichols G, Pedraza-Díaz S, McLauchlin J (June 2006). "Genetic analysis of Cryptosporidium from 2414 humans with diarrhoea in England between 1985 and 2000". J. Med. Microbiol. 55 (Pt 6): 703–7. doi:10.1099/jmm.0.46251-0. PMID 16687587.
^ Fayer R (December 2004). "Cryptosporidium: a water-borne zoonotic parasite". Vet. Parasitol. 126 (1–2): 37–56. doi:10.1016/j.vetpar.2004.09.004. PMID 15567578.
^ Morgan-Ryan UM, Fall A, Ward LA; et al. (2002). "Cryptosporidium hominis n. sp. (Apicomplexa: Cryptosporidiidae) from Homo sapiens". J. Eukaryot. Microbiol. 49 (6): 433–40. doi:10.1111/j.1550-7408.2002.tb00224.x. PMID 12503676.
^ Cacciò SM, Thompson RC, McLauchlin J, Smith HV (September 2005). "Unravelling Cryptosporidium and Giardia epidemiology". Trends Parasitol. 21 (9): 430–7. doi:10.1016/j.pt.2005.06.013. PMID 16046184.
^ Wielinga PR, de Vries A, van der Goot TH; et al. (June 2008). "Molecular epidemiology of Cryptosporidium in humans and cattle in The Netherlands". Int. J. Parasitol. 38 (7): 809–17. doi:10.1016/j.ijpara.2007.10.014. PMID 18054936.
^ http://www.cdc.gov/NCIDOD/DPD/parasites/cryptosporidiosis/factsht_cryptosporidiosis.htm#10; CDC Cryptosporidiosis Fact Sheet. Retrieved on 18 April 2008
^ http://www.hominis.mic.vcu.edu/index.html; Virginia Commonwealth University CSBC Cryptosporidium Research Website. Retrieved on 18 April 2008

UpToDate Contents

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1. クリプトスポリジウム症の治療および予防 treatment and prevention of cryptosporidiosis
2. クリプトスポリジウム症の疫学、臨床症状、および診断 epidemiology clinical manifestations and diagnosis of cryptosporidiosis
3. 犬および猫以外のペットからの人畜共通感染症 zoonoses from pets other than dogs and cats
4. 資源に富んだ国における急性下痢の疫学および原因 epidemiology and causes of acute diarrhea in resource rich countries
5. 開発途上国の小児における持続性下痢 persistent diarrhea in children in resource limited countries

English Journal

Population structure of natural and propagated isolates of Cryptosporidium parvum, C. hominis and C. meleagridis.

Widmer G1, Ras R, Chalmers RM, Elwin K, Desoky E, Badawy A.
Environmental microbiology.Environ Microbiol.2015 Apr;17(4):984-93. doi: 10.1111/1462-2920.12447. Epub 2014 Apr 2.
The three protozoan species Cryptosporidium parvum, C. meleagridis and C. hominis (phylum Apicomplexa) are enteric pathogens of humans. The former two species are zoonotic and the latter is thought to infect only humans. To better characterize the structure and transmission of natural and labora
PMID 24593863

Investigation of a swimming pool-associated cryptosporidiosis outbreak in the Kimberley region of Western Australia.

Ng-Hublin JS1, Hargrave D2, Combs B3, Ryan U1.
Epidemiology and infection.Epidemiol Infect.2015 Apr;143(5):1037-41. doi: 10.1017/S095026881400106X. Epub 2014 Jun 26.
SUMMARY Cryptosporidiosis is a gastroenteric disease caused by the protozoan parasite Cryptosporidium, which manifests primarily as watery diarrhoea. Transmitted via the faecal-oral route, infection with the parasite can occur through ingestion of water, food or other fomites contaminated with its i
PMID 25703474

Japanese Journal

Molecular characterization and assessment of zoonotic transmission of Cryptosporidium from dairy cattle in West Bengal, India

Veterinary Parasitology 171(1-2), 41-47, 2010-07-15
NAID 120004247123

Prevalence of Cryptosporidium, Cyclospora cayetanensis and Isospora belli infection among diarrheal patients in South India

Tropical medicine and health 36(3), 131-136, 2008-09-01
NAID 10024379108

「クリプトスポリジウム症」

Cryptosporidium hominis
Scientific classification
Domain:	Eukaryota
(unranked):	SAR supergroup
Superphylum:	Alveolata
Phylum:	Apicomplexa
Class:	Conoidasida
Subclass:	Coccidiasina
Order:	Eucoccidiorida
Suborder:	Eimeriorina
Family:	Cryptosporidiidae
Genus:	Cryptosporidium
Species:	C. hominis
Binomial name
	Cryptosporidium hominis;