Cryptosporidiosis pathophysiology: Difference between revisions

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{{Cryptosporidiosis}}
==Overview==
Cryptosporidiosis is a zoonotic disease, humans could be infected by contact with contaminated water and through inhalation of the spores. Following transmission, white blood cells phagocyte the pathogen and transports it via hematologic or lymphatic route to different organs.<ref name="urlGeneral Information | Cryptosporidium | Parasites | CDC">{{cite web |url=https://www.cdc.gov/parasites/crypto/general.html |title=General Information &#124; Cryptosporidium &#124; Parasites &#124; CDC |format= |work= |accessdate=}}</ref><ref name="pmid22685452">{{cite journal |vauthors=Leitch GJ, He Q |title=Cryptosporidiosis-an overview |journal=J Biomed Res |volume=25 |issue=1 |pages=1–16 |year=2012 |pmid=22685452 |pmc=3368497 |doi=10.1016/S1674-8301(11)60001-8 |url=}}</ref>
==Pathophysiology==
The pathophysiology of cryptosporidiosis can be described in the following steps
===Transmission===
* Transmission of [[Cryptosporidium parvum]] and C. hominis occurs mainly through contact with contaminated water (e.g., drinking or recreational water). 
*Occasionally food sources, such as chicken salad, may serve as vehicles for transmission. 
*Many outbreaks in the United States have occurred in waterparks, community swimming pools, and day care centers.
*[[Zoonotic]] and anthroponotic transmission of C. parvum and anthroponotic transmission of C. hominis occur through exposure to infected animals or exposure to water contaminated by feces of infected animals.
===Incubation===
* Incubation period for cryptosporidiosis is of 7 days (but can vary from 2 to 10 days).
===Dissemination===
* Following ingestion (and possibly inhalation) by a suitable host, excystation occurs. 
* The sporozoites are released and parasitize [[epithelial cell]]s of the [[gastrointestinal tract]] or other tissues such as the [[respiratory tract]]. 
===Pathogenesis===
* In these cells, the parasites undergo asexual multiplication ([[schizogony]] or [[merogony]]) and then sexual multiplication ([[gametogony]]) producing microgamonts (male) and macrogamonts (female).
* Upon [[fertilization]] of the macrogamonts by the microgametes, oocysts develop that sporulate in the infected host. 
* Two different types of oocysts are produced, the thick-walled, which is commonly excreted from the host, and the thin-walled oocyst, which is primarily involved in autoinfection.
*Oocysts are infective upon excretion, thus permitting direct and immediate fecal-oral transmission.
*Oocysts of [[Cyclospora cayetanensis]], another important coccidian [[parasite]], are unsporulated at the time of excretion and do not become infective until sporulation is completed.
[[Image:Cryptosporidiosis 01.png|thumb|center|400px|Life cycle of Cryptosporidium spp.]]
==Gallery==
<gallery>
Image: Cryptosporidiosis07.jpeg| Life cycle of different species of Cryptosporidium, the causal agents of Cryptosporidiosis. <SMALL><SMALL>''[http://phil.cdc.gov/phil/home.asp From Public Health Image Library (PHIL).] ''<ref name=PHIL> {{Cite web | title = Public Health Image Library (PHIL) | url = http://phil.cdc.gov/phil/home.asp}}</ref></SMALL></SMALL>


==Overview==
==Infectious agents==
A number of species of ''Cryptosporidium'' infect mammals. In humans the main causes of disease are ''[[Cryptosporidium parvum|C. parvum]]'' and ''C. hominis'' (previously ''C. parvum'' genotype 1). ''C. canis'', ''C. felis'', ''C. meleagridis'', and ''C. muris'' can also cause disease in humans.


==Life cycle==
</gallery>
[[Image:Cryptosporidiosis 01.png|thumb|left|300px|Life cycle of ''Cryptosporidium'' spp.]]
''Cryptosporidium'' has a [[spore]] phase ([[oocyst]]) and in this state it can survive for lengthy periods outside a host. It can also resist many common disinfectants, notably chlorine-based disinfectants.<ref>{{cite web |url=http://www.cdc.gov/ncidod/eid/vol5no4/carpenter.htm |title=Chlorine Disinfection of Recreational Water for ''Cryptosporidium parvum'' |publisher=CDC |accessdate=6 May 2007}}</ref>


The life cycle of ''Cryptosporidium parvum'' consists of an asexual stage and a sexual stage.<ref name=cdc/>  After being ingested, the oocysts excyst in the small intestine.  They release sporozoites that attach to the microvilli of the epithelial cells of the small intestine.  From there they become trophozoites that reproduce asexually by multiple fission, a process known as schizogony.  The trophozoites develop into Type 1 [[meront]]s [1] that contain 8 daughter cells.<ref name=ryan/>  These daughter cells are Type 1 merozoites, which get released by the meronts.  Some of these merozoites can cause autoinfection by attaching to epithelial cells.  Others of these merozoites become Type II meronts,<ref name=chen/> which contain 4 Type II merozoites.<ref name=ryan/>  These merozoites get released and they attach to the epithelial cells.  From there they become either macrogamonts or microgamonts.<ref name=chen/>  These are the female and male sexual forms, respectively.<ref name=ryan/>  This stage, when sexual forms arise, is called gametogony.<ref name=murray>Murray, Patrick R., Ken S. Rosenthal, and Michael A. Pfaller. Medical Microbiology. 5th ed. Philadelphia: Elsevier Inc., 2005: 855-856.</ref> Zygotes are formed by microgametes from the microgamont penetrating the macrogamonts.  The zygotes develop into oocysts of two types.<ref name=chen/>  20% of oocysts have thin walls and so can reinfect the host by rupturing and releasing sporozoites that start the process over again.<ref name=ryan/>  The thick-walled oocysts are excreted into the environment.<ref name=chen/>  The oocysts are mature and infective upon being excreted.<ref name=ryan/>  They can survive in the environment for months.<ref name=gideon>{{cite web |title=Cryptosporidiosis |publisher=Gideon |date=23 February 2009 |url=http://web.gideononline.com/web/tox_diseases/index.php?disease=355&view=General |quote=Trial subscription required to access}}</ref>


==References==
==References==
{{Reflist|2}}
{{Reflist|2}}
[[Category:Needs overview]]
[[Category:Parasitic diseases]]
[[Category:Disease]]
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Latest revision as of 17:31, 18 September 2017

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Kalsang Dolma, M.B.B.S.[2]

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Overview

Cryptosporidiosis is a zoonotic disease, humans could be infected by contact with contaminated water and through inhalation of the spores. Following transmission, white blood cells phagocyte the pathogen and transports it via hematologic or lymphatic route to different organs.[1][2]

Pathophysiology

The pathophysiology of cryptosporidiosis can be described in the following steps

Transmission

  • Transmission of Cryptosporidium parvum and C. hominis occurs mainly through contact with contaminated water (e.g., drinking or recreational water).
  • Occasionally food sources, such as chicken salad, may serve as vehicles for transmission.
  • Many outbreaks in the United States have occurred in waterparks, community swimming pools, and day care centers.
  • Zoonotic and anthroponotic transmission of C. parvum and anthroponotic transmission of C. hominis occur through exposure to infected animals or exposure to water contaminated by feces of infected animals.

Incubation

  • Incubation period for cryptosporidiosis is of 7 days (but can vary from 2 to 10 days).

Dissemination

Pathogenesis

  • In these cells, the parasites undergo asexual multiplication (schizogony or merogony) and then sexual multiplication (gametogony) producing microgamonts (male) and macrogamonts (female).
  • Upon fertilization of the macrogamonts by the microgametes, oocysts develop that sporulate in the infected host.
  • Two different types of oocysts are produced, the thick-walled, which is commonly excreted from the host, and the thin-walled oocyst, which is primarily involved in autoinfection.
  • Oocysts are infective upon excretion, thus permitting direct and immediate fecal-oral transmission.
  • Oocysts of Cyclospora cayetanensis, another important coccidian parasite, are unsporulated at the time of excretion and do not become infective until sporulation is completed.
Life cycle of Cryptosporidium spp.

Gallery


References

  1. "General Information | Cryptosporidium | Parasites | CDC".
  2. Leitch GJ, He Q (2012). "Cryptosporidiosis-an overview". J Biomed Res. 25 (1): 1–16. doi:10.1016/S1674-8301(11)60001-8. PMC 3368497. PMID 22685452.
  3. "Public Health Image Library (PHIL)".


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