Echinococcus: Difference between revisions
Gerald Chi (talk | contribs) mNo edit summary |
No edit summary |
||
| (2 intermediate revisions by one other user not shown) | |||
| Line 26: | Line 26: | ||
In humans, this causes a disease called [[echinococcosis]]. Latency can be up to 50 years, and is mostly found in South and Central America, the Middle East, China, and the West of the U.S.A. (e.g.. Arizona, New Mexico and California). | In humans, this causes a disease called [[echinococcosis]]. Latency can be up to 50 years, and is mostly found in South and Central America, the Middle East, China, and the West of the U.S.A. (e.g.. Arizona, New Mexico and California). | ||
Human [[echinococcosis]] ([[hydatidosis]] or [[hydatid disease]]) is caused by the larval stages of [[cestodes]] ([[tapeworms]]) of the genus [[Echinococcus]]. [[Echinococcus granulosus|''Echinococcus granulosus'']] causes [[cystic echinococcosis]] (CE), the form most frequently encountered; [[E. multilocularis|''E. multilocularis'']] causes [[alveolar echinococcosis]] (AE); ''E. vogeli'' causes polycystic echinococcosis; and ''E. oligarthrus'' is an extremely rare cause of human [[echinococcosis]]. [[Echinococcus]] eggs contain an [[embryo]] that is called an oncosphere or hexcanth. From the [[embryo]] released from an egg develops a [[hydatid cyst]], which is able to survive within [[organs]] for years. [[Echinococcus]] adult [[Worm|worms]] develop from protoscolices and are typically 6mm or less in length and have a [[scolex]], neck and typically three [[Proglottid|proglottids]]. | |||
===Eggs=== | |||
[[Echinococcus]] eggs contain an [[embryo]] that is called an oncosphere or hexcanth. The name of this embryo stems from the fact that these [[Embryo|embryos]] have six hooklets. The eggs are passed through the [[feces]] of the [[definitive host]] (dogs and other carnivores) and it is the [[ingestion]] of these eggs that lead to [[infection]] in the [[intermediate host]] (sheep, cattle, horses, and camel). | |||
===Larval/hydatid cyst stage=== | |||
From the [[embryo]] released from an egg develops a [[hydatid cyst]], which grows to about 5–10 cm within the first year and is able to survive within [[organs]] for years.<ref>Mandell, Gerald L. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, PA: Elsevier Inc., 2010. Ch. 290. Print.</ref> [[Cysts]] sometimes grow to be so large that by the end of several years or even decades, they can contain several liters of [[fluid]]. Once a [[cyst]] has reached a diameter of 1 cm, its wall differentiates into a thick outer, non-cellular [[membrane]], which covers the thin [[germinal epithelium]]. From this [[epithelium]], cells begin to grow within the [[cyst]]. These cells then become vacuolated and are known as brood capsules, which are the parts of the [[Parasites|parasite]] from which protoscolices bud. Often, daughter [[cysts]] will also form within [[cysts]]. | |||
===Adult worm=== | |||
[[Echinococcus]] adult worms develop from protoscolices and are typically 6mm or less in length and have a [[scolex]], neck and typically three [[Proglottid|proglottids]], one of which is immature, another of which is mature and the third of which is gravid (or containing eggs). The [[scolex]] of the adult worm contains four suckers and a rostellum that has about 25-50 hooks.<ref>CDC. "Parasite Image Library: Echinococcosis." DPDx. CDC, Web. 20 February 2010. <http://www.dpd.cdc.gov/dpdx/HTML/ImageLibrary/Echinococcosis_il.htm>.</ref> | |||
===Morphological differences among different species=== | |||
The major morphological difference among different species of [[Echinococcus]] is the length of the tapeworm. ''[[Echinococcus granulosus|E. granulosus]]'' is approximately 2 to 7 mm while ''[[E. multilocularis]]'' is often smaller and is 4 mm or less.<ref name="bare_url">Eckert, Johannes, and Peter Deplazes. "Biological, Epidemiological, and Clinical Aspects of Echinococcosis, a Zoonosis of Increasing Concern." Clinical Microbiology Reviews 17.1 (2004): 107-135. Web. 5 February 2010..</ref> On the other hand, ''E. vogeli'' is found to be up to 5.6 mm long and ''E. oligarthus'' is found to be up to 2.9 mm long. In addition to the difference in length, there are also differences in the [[Hydatid cyst|hydatid cysts]] of the different [[species]]. For instance, in ''[[E. multilocularis]]'', the [[cysts]] have an ultra thin limiting [[membrane]] and the [[germinal epithelium]] may bud externally. Furthermore, ''[[E. granulosus]]'' [[cysts]] are [[Unilocular hydatid disease|unilocular]] and full of fluid while ''[[E. multilocularis]]'' [[cysts]] contain little fluid and are multilocular. For ''E. vogeli'', its [[Hydatid cyst|hydatid cysts]] are large and are actually polycystic since the germinal membrane of the [[hydatid cyst]] actually [[Proliferate|proliferates]] both inward, to create [[septa]] that divide the hydatid into [[sections]], and outward, to create new [[cysts]]. Like ''[[E. granulosus]]'' [[Cyst|cysts]], ''E. vogeli'' [[Cyst|cysts]] are filled with [[fluid]]. | |||
==See Also== | ==See Also== | ||
* [[Echinococcus multilocularis]] | |||
* [[Echinococcus shiquicus]] | |||
* [[Echinococcus granulosus]] | |||
==Gallery== | |||
<gallery> | |||
Image: Echinococcus05.jpeg| Scolex of Echinococcus granulosus from hydatid cyst. <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> | |||
Image: Echinococcus02.jpeg| Photomicrograph reveals some of the ultrastructural morphology exhibited by an adult cestode, Echinococcus granulosus, found in a dog. E. granulosus causes “cystic echinococcosis”. <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> | |||
</gallery> | |||
== References == | |||
{{reflist|2}} | |||
Latest revision as of 17:28, 21 August 2017
| Echinococcus | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Scientific classification | ||||||||||||
| ||||||||||||
| Species | ||||||||||||
|
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
The genus Echinococcus includes six species of cyclophyllid tapeworms to date, of the family Taeniidae. Infection with Echinococcus results in hydatid disease, also known as echinococcosis.
In humans, this causes a disease called echinococcosis. Latency can be up to 50 years, and is mostly found in South and Central America, the Middle East, China, and the West of the U.S.A. (e.g.. Arizona, New Mexico and California). Human echinococcosis (hydatidosis or hydatid disease) is caused by the larval stages of cestodes (tapeworms) of the genus Echinococcus. Echinococcus granulosus causes cystic echinococcosis (CE), the form most frequently encountered; E. multilocularis causes alveolar echinococcosis (AE); E. vogeli causes polycystic echinococcosis; and E. oligarthrus is an extremely rare cause of human echinococcosis. Echinococcus eggs contain an embryo that is called an oncosphere or hexcanth. From the embryo released from an egg develops a hydatid cyst, which is able to survive within organs for years. Echinococcus adult worms develop from protoscolices and are typically 6mm or less in length and have a scolex, neck and typically three proglottids.
Eggs
Echinococcus eggs contain an embryo that is called an oncosphere or hexcanth. The name of this embryo stems from the fact that these embryos have six hooklets. The eggs are passed through the feces of the definitive host (dogs and other carnivores) and it is the ingestion of these eggs that lead to infection in the intermediate host (sheep, cattle, horses, and camel).
Larval/hydatid cyst stage
From the embryo released from an egg develops a hydatid cyst, which grows to about 5–10 cm within the first year and is able to survive within organs for years.[1] Cysts sometimes grow to be so large that by the end of several years or even decades, they can contain several liters of fluid. Once a cyst has reached a diameter of 1 cm, its wall differentiates into a thick outer, non-cellular membrane, which covers the thin germinal epithelium. From this epithelium, cells begin to grow within the cyst. These cells then become vacuolated and are known as brood capsules, which are the parts of the parasite from which protoscolices bud. Often, daughter cysts will also form within cysts.
Adult worm
Echinococcus adult worms develop from protoscolices and are typically 6mm or less in length and have a scolex, neck and typically three proglottids, one of which is immature, another of which is mature and the third of which is gravid (or containing eggs). The scolex of the adult worm contains four suckers and a rostellum that has about 25-50 hooks.[2]
Morphological differences among different species
The major morphological difference among different species of Echinococcus is the length of the tapeworm. E. granulosus is approximately 2 to 7 mm while E. multilocularis is often smaller and is 4 mm or less.[3] On the other hand, E. vogeli is found to be up to 5.6 mm long and E. oligarthus is found to be up to 2.9 mm long. In addition to the difference in length, there are also differences in the hydatid cysts of the different species. For instance, in E. multilocularis, the cysts have an ultra thin limiting membrane and the germinal epithelium may bud externally. Furthermore, E. granulosus cysts are unilocular and full of fluid while E. multilocularis cysts contain little fluid and are multilocular. For E. vogeli, its hydatid cysts are large and are actually polycystic since the germinal membrane of the hydatid cyst actually proliferates both inward, to create septa that divide the hydatid into sections, and outward, to create new cysts. Like E. granulosus cysts, E. vogeli cysts are filled with fluid.
See Also
Gallery
-
![Scolex of Echinococcus granulosus from hydatid cyst. From Public Health Image Library (PHIL). [4]](/images/0/05/Echinococcus05.jpeg)
Scolex of Echinococcus granulosus from hydatid cyst. From Public Health Image Library (PHIL). [4]
-
![Photomicrograph reveals some of the ultrastructural morphology exhibited by an adult cestode, Echinococcus granulosus, found in a dog. E. granulosus causes “cystic echinococcosis”. From Public Health Image Library (PHIL). [4]](/images/a/a8/Echinococcus02.jpeg)
Photomicrograph reveals some of the ultrastructural morphology exhibited by an adult cestode, Echinococcus granulosus, found in a dog. E. granulosus causes “cystic echinococcosis”. From Public Health Image Library (PHIL). [4]
![Scolex of Echinococcus granulosus from hydatid cyst. From Public Health Image Library (PHIL). [4]](/index.php/File:Echinococcus05.jpeg)
![Photomicrograph reveals some of the ultrastructural morphology exhibited by an adult cestode, Echinococcus granulosus, found in a dog. E. granulosus causes “cystic echinococcosis”. From Public Health Image Library (PHIL). [4]](/index.php/File:Echinococcus02.jpeg)
References
- ↑ Mandell, Gerald L. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, PA: Elsevier Inc., 2010. Ch. 290. Print.
- ↑ CDC. "Parasite Image Library: Echinococcosis." DPDx. CDC, Web. 20 February 2010. <http://www.dpd.cdc.gov/dpdx/HTML/ImageLibrary/Echinococcosis_il.htm>.
- ↑ Eckert, Johannes, and Peter Deplazes. "Biological, Epidemiological, and Clinical Aspects of Echinococcosis, a Zoonosis of Increasing Concern." Clinical Microbiology Reviews 17.1 (2004): 107-135. Web. 5 February 2010..
- ↑ 4.0 4.1 "Public Health Image Library (PHIL)".