Echinococcosis pathophysiology: Difference between revisions

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{{Echinococcosis}}
{{Echinococcosis}}


{{CMG}} '''Associate Editor-In-Chief:''' {{CZ}}
{{CMG}} '''Associate Editor-In-Chief:''' {{MIR}} {{CZ}}; {{KD}}
==Overview==
==Overview==
The [[Transmission (medicine)|transmission]] of [[echinococcosis]] from the [[definitive host]] to the [[intermediate host]] is by [[ingestion]] of embryonated eggs passed in the [[feces]]. Once the eggs are [[Ingestion|ingested]] they hatch in the [[small intestine]] and develop into onchospheres. There oncospheres reach various [[organs]] by migration through the [[vascular system]] and develop into [[cysts]] producing protoscolices. The definitive host is [[infected]] by [[ingestion]] of the organs [[infected]] with the [[cysts]]. After [[ingestion]] of the [[cysts]] they evaginate and [[Invasion|invade]] the [[intestinal mucosa]] and develop into adult worms.
==Pathophysiology==
==Pathophysiology==
[[Image:Echinococcus LifeCycle.gif|500px|left]]
===Life cycle===
[[Image:Echinococcus LifeCycle.gif|frame|Courtesy dedicated to CDC.com|450px|center]]
<small>'''(1)'''The adult [[Echinococcus granulosus]] '''(2)''' Embryonated eggs  '''(3)''' Oncosphere '''(4)''' [[Cyst]] '''(5)''' Protoscolices  '''(6)'''  Protoscolices evaginating</small>


===Trasmission of [[infection]]<ref name="pmid23378949">{{cite journal |vauthors=Rasheed K, Zargar SA, Telwani AA |title=Hydatid cyst of spleen: a diagnostic challenge |journal=N Am J Med Sci |volume=5 |issue=1 |pages=10–20 |year=2013 |pmid=23378949 |pmc=3560132 |doi=10.4103/1947-2714.106184 |url=}}</ref><ref name="pmid27047771">{{cite journal |vauthors=Pakala T, Molina M, Wu GY |title=Hepatic Echinococcal Cysts: A Review |journal=J Clin Transl Hepatol |volume=4 |issue=1 |pages=39–46 |year=2016 |pmid=27047771 |pmc=4807142 |doi=10.14218/JCTH.2015.00036 |url=}}</ref><ref name="pmid22110535">{{cite journal |vauthors=Siracusano A, Delunardo F, Teggi A, Ortona E |title=Host-parasite relationship in cystic echinococcosis: an evolving story |journal=Clin. Dev. Immunol. |volume=2012 |issue= |pages=639362 |year=2012 |pmid=22110535 |pmc=3206507 |doi=10.1155/2012/639362 |url=}}</ref><ref name="urlCDC - DPDx - Echinococcosis">{{cite web |url=https://www.cdc.gov/dpdx/echinococcosis/index.html |title=CDC - DPDx - Echinococcosis |format= |work= |accessdate=}}</ref>===
*The [[Transmission (medicine)|transmission]] of [[echinococcosis]] from the definitive host (dogs and other carnivores) to the [[intermediate host]] (sheep, goats, swine etc) occurs by the [[ingestion]] of embryonated eggs passed in the [[feces]].
*The definitive host is [[Infection (disambiguation)|infected]] by the [[ingestion]] of [[cyst]] containing organs of the [[Infection (disambiguation)|infected]] [[intermediate host]] (sheep, goats, swine, etc).
===[[Pathogenesis]]<ref name="pmid23378949">{{cite journal |vauthors=Rasheed K, Zargar SA, Telwani AA |title=Hydatid cyst of spleen: a diagnostic challenge |journal=N Am J Med Sci |volume=5 |issue=1 |pages=10–20 |year=2013 |pmid=23378949 |pmc=3560132 |doi=10.4103/1947-2714.106184 |url=}}</ref><ref name="pmid27047771">{{cite journal |vauthors=Pakala T, Molina M, Wu GY |title=Hepatic Echinococcal Cysts: A Review |journal=J Clin Transl Hepatol |volume=4 |issue=1 |pages=39–46 |year=2016 |pmid=27047771 |pmc=4807142 |doi=10.14218/JCTH.2015.00036 |url=}}</ref><ref name="pmid22110535">{{cite journal |vauthors=Siracusano A, Delunardo F, Teggi A, Ortona E |title=Host-parasite relationship in cystic echinococcosis: an evolving story |journal=Clin. Dev. Immunol. |volume=2012 |issue= |pages=639362 |year=2012 |pmid=22110535 |pmc=3206507 |doi=10.1155/2012/639362 |url=}}</ref><ref name="urlCDC - DPDx - Echinococcosis">{{cite web |url=https://www.cdc.gov/dpdx/echinococcosis/index.html |title=CDC - DPDx - Echinococcosis |format= |work= |accessdate=}}</ref>===
*The embronated eggs are [[excreted]] in the [[feces]] of the [[definitive host]], which include dogs and other carnivores.
*The [[intermediate hosts]] include: sheep, cattle, horses and camel. Once [[Ingestion|ingested]] the eggs hatch in the [[Small intestine|small bowel]] and release oncospheres.
*The onchospheres penetrate the [[intestinal wall]] and migrate through the [[vascular system]] to organs such as [[liver]] and [[lung]].
*In the [[Lung|lungs]] and [[liver]] the oncospheres develop into a [[cyst]] producing protoscolices and daughter [[cysts]] which fill the interior of the [[cyst]].
*The [[Definitive host|definite host]] will be [[Infection (disambiguation)|infected]] if they [[ingest]] organs containing [[cysts]].
*Once [[Ingest|ingested]], the protoscolices evaginate and attach the [[intestinal mucosa]].
*In 32 to 80 days after evagination the protoscolices develop into adult [[Tapeworms|tapeworm]].
*The [[life cycle]] of [[Echinococcus multilocularis|E. multilocularis]] is similar to the [[life cycle]] of [[Echinococcus granulosus]], but with the following differences: The [[Definitive host|definitive hosts]] are foxes, and to a lesser extent dogs, cats, coyotes and wolves. The [[intermediate host]] are small rodents and the larval growth (in the [[liver]]) remains indefinitely in the proliferative stage, resulting in [[Invasive (medical)|invasion]] of the surrounding [[tissues]].
*In the [[life cycle]] of E. vogeli the [[Definitive host|definitive hosts]] are bush dogs and dogs. The [[intermediate hosts]] are rodents and the larval stage in the [[liver]], [[lung]] develops both externally and internally, resulting in multiple [[Vesicle|vesicles]].
*''E. oligarthrus'' (up to 2.9 mm long) has a [[life cycle]] that involves wild felids as [[Definitive host|definitive hosts]] and rodents as [[intermediate hosts]]. Humans become [[infected]] by [[Ingestion|ingesting]] eggs , with resulting release of oncospheres  in the [[intestine]] and the development of [[Cyst|cysts]] in various organs.


The adult [[Echinococcus granulosus]] (3 to 6 mm long) '''(1)''' resides in the small bowel of the [[definitive host]]s, dogs or other canids. Gravid proglottids release eggs '''(2)''' that are passed in the feces. After ingestion by a suitable intermediate host (under natural conditions: sheep, goat, swine, cattle, horses, camel), the egg hatches in the small bowel and releases an [[oncosphere]] '''(3)''' that penetrates the [[intestinal wall]] and migrates through the circulatory system into various [[organ]]s, especially the liver and lungs. In these organs, the oncosphere develops into a cyst '''(4)'''that enlarges gradually, producing [[protoscolices]] '''(5)''' and daughter [[cyst]]s that fill the cyst interior. The definitive host becomes infected by ingesting the cyst-containing organs of the infected [[intermediate host]]. After ingestion, the protoscolices  evaginate, attach to the [[intestinal mucosa]] '''(6)''' , and develop into adult stages '''(1)''' in 32 to 80 days.
===Gross Pathology<ref name="urlCDC - DPDx - Echinococcosis" />===
The most important gross pathological features of echinococcus cysts are:
* Cysts of E. granulosis (cystic hydatid disease):
** Cysts tend to be:
*** Filled with clear fluid
*** White appearance
*** Solitary
*** [[Unilocular hydatid disease|Unilocular]]
** Mostly involve right lobe of [[liver]]
** Viable cysts are filled with a colorless fluid that contains daughter cysts and brood capsules with scolices
** Daughter cysts may also be present outside the [[fibrous]] layer of the cyst, that are called as extracapsular or satellite cysts
* Cysts of E. multilocularis ([[alveolar hydatid disease]]):
** Numerous small and irregular [[cysts]]
** Mostly smaller than 2 cm
** Appears infiltrative
[[Image:hydatid_cyst_membrane.jpg|thumb|center|500px|<SMALL><SMALL>''[https://commons.wikimedia.org Courtesy to wikimedia]''</SMALL></SMALL>]]
[[File:Liver hydatic gross.jpg|thumb|center|500px|<SMALL><SMALL>''[https://radiopaedia.com Courtesy to radiopaedia]''</SMALL></SMALL>]]


The same life cycle occurs with [[E. multilocularis]] (1.2 to 3.7 mm), with the following differences: the definitive hosts are foxes, and to a lesser extent dogs, cats, coyotes and wolves; the intermediate host are small rodents; and larval growth (in the [[liver]]) remains indefinitely in the proliferative stage, resulting in invasion of the surrounding tissues. With E. vogeli (up to 5.6 mm long), the definitive hosts are bush dogs and dogs; the intermediate hosts are rodents; and the larval stage (in the [[liver]], [[lung]]s and other organs) develops both externally and internally, resulting in multiple vesicles. E. oligarthrus (up to 2.9 mm long) has a life cycle that involves wild felids as definitive hosts and rodents as intermediate hosts. Humans become infected by ingesting eggs , with resulting release of oncospheres  in the intestine and the development of cysts (4), , , , ,  in various organs.
===Microscopic pathology<ref name="urlCDC - DPDx - Echinococcosis" />===
On microscopic pathology of the tissues, the most important findings include:
*Cysts can be found in any part of the body, but are most common in the liver, lung and central nervous system
*Echinococcus granulosus cyst:
**Cyst wall composed of an acellular laminated external layer and a thin, germinal (nucleated) inner layer
**Brood capsule with protoscoleces inside
[[File:Webp.net-gifmaker (32).gif|thumb|center|500px|<SMALL><SMALL>''[https://www.cdc.gov/dpdx/echinococcosis/index.html Courtesy to CDC]''</SMALL></SMALL>]]
[[File:Echinococcus granulosus scolex.jpg|thumb|center|500px|<SMALL><SMALL>''[https://commons.wikimedia.org Courtesy to wikimedia<br>Echinococcus granulosus scolex close-up]''</SMALL></SMALL>]]


== References ==
== References ==
{{reflist|2}}
{{reflist|2}}
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Latest revision as of 21:32, 29 July 2020

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor-In-Chief: Mahshid Mir, M.D. [2] Cafer Zorkun, M.D., Ph.D. [3]; Kalsang Dolma, M.B.B.S.[4]

Overview

The transmission of echinococcosis from the definitive host to the intermediate host is by ingestion of embryonated eggs passed in the feces. Once the eggs are ingested they hatch in the small intestine and develop into onchospheres. There oncospheres reach various organs by migration through the vascular system and develop into cysts producing protoscolices. The definitive host is infected by ingestion of the organs infected with the cysts. After ingestion of the cysts they evaginate and invade the intestinal mucosa and develop into adult worms.

Pathophysiology

Life cycle

Courtesy dedicated to CDC.com

(1)The adult Echinococcus granulosus (2) Embryonated eggs (3) Oncosphere (4) Cyst (5) Protoscolices (6) Protoscolices evaginating

Trasmission of infection[1][2][3][4]

Pathogenesis[1][2][3][4]

Gross Pathology[4]

The most important gross pathological features of echinococcus cysts are:

  • Cysts of E. granulosis (cystic hydatid disease):
    • Cysts tend to be:
      • Filled with clear fluid
      • White appearance
      • Solitary
      • Unilocular
    • Mostly involve right lobe of liver
    • Viable cysts are filled with a colorless fluid that contains daughter cysts and brood capsules with scolices
    • Daughter cysts may also be present outside the fibrous layer of the cyst, that are called as extracapsular or satellite cysts
  • Cysts of E. multilocularis (alveolar hydatid disease):
    • Numerous small and irregular cysts
    • Mostly smaller than 2 cm
    • Appears infiltrative
Courtesy to wikimedia
Courtesy to radiopaedia

Microscopic pathology[4]

On microscopic pathology of the tissues, the most important findings include:

  • Cysts can be found in any part of the body, but are most common in the liver, lung and central nervous system
  • Echinococcus granulosus cyst:
    • Cyst wall composed of an acellular laminated external layer and a thin, germinal (nucleated) inner layer
    • Brood capsule with protoscoleces inside
Courtesy to CDC
Courtesy to wikimedia
Echinococcus granulosus scolex close-up

References

  1. 1.0 1.1 Rasheed K, Zargar SA, Telwani AA (2013). "Hydatid cyst of spleen: a diagnostic challenge". N Am J Med Sci. 5 (1): 10–20. doi:10.4103/1947-2714.106184. PMC 3560132. PMID 23378949.
  2. 2.0 2.1 Pakala T, Molina M, Wu GY (2016). "Hepatic Echinococcal Cysts: A Review". J Clin Transl Hepatol. 4 (1): 39–46. doi:10.14218/JCTH.2015.00036. PMC 4807142. PMID 27047771.
  3. 3.0 3.1 Siracusano A, Delunardo F, Teggi A, Ortona E (2012). "Host-parasite relationship in cystic echinococcosis: an evolving story". Clin. Dev. Immunol. 2012: 639362. doi:10.1155/2012/639362. PMC 3206507. PMID 22110535.
  4. 4.0 4.1 4.2 4.3 "CDC - DPDx - Echinococcosis".

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