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{{Amoebiasis}}
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{{CMG}}; {{AE}} {{JH}}
{{CMG}}; {{AE}} {{YD}}; {{SSK}}


==Overview==
==Overview==
Symptoms can range from mild diarrhoea to [[dysentery]]  with blood and mucus. The blood comes from amoebae invading the lining of the intestine. In about 10% of invasive cases the amoebae enter the bloodstream and may travel to other organs in the body. Most commonly this means the liver, as this is where blood from the intestine reaches first, but they can end up almost anywhere.
==Pathophysiology==
 
===Transmission===
==Transmission==
*''E. histolytica'' cyst is usually transmitted by the fecal-oral route through contaminated drinking water or food)
*''E. histolytica'' cyst is usually transmitted by the fecal-oral route through contaminated drinking water or food)
*''E. histolytica'' cyst may also be transmitted indirectly through direct contact with infected individuals.
*''E. histolytica'' cyst may also be transmitted indirectly through direct contact with infected individuals.
===Pathogenesis===
*Following transmission, ''E. histolytica'' trophozoites inhabit in the large intestine of the human host.
*In the large intestine, the trophozoite invades the intestinal mucosa into the blood stream. Simultaneously, they form resistant cysts that are then excreted in human stools.
*Once in the bloodstream, the trophozoite migrates into the portal circulation and develops amebic liver abscess.
====Invasion of Intestinal Mucosa====
*''E. histolytica'' trophozoites secrete proteases, which induce the release of mucin from goblet cells, resulting in glandular hyperplasia.
*''E. histolytica'' is
===Gross Pathology===
On gross pathology, the following findings may be present in patients with amebiasis:
*Wavy surface epithelium (results from focal release of mucin and spasm of the muscular layer)
*Nodular and/or irregular ulcers in the cecum (most common), sigmoid colon, and rectum. Early ulcers are usually in the interglandular epithelium.
:*Nodular: small (sub-centrimetric), rounded, elevated lesions with necrotic center and edematous rim
:*Irregular: large (1-5 cm), shallow with broad elevated margins
Note: the mucosal folds may occasionally hide small colonic ulcers (false-negative results)
===Microscopic Pathology===
*On microscopic pathology, amebiasis is characterized by a flask ulcer (deep, microhemorrhagic ulceration involving the submucosa), which is a characteristic of advanced disease.
*Additional findings may be present in patients with amebiasis:
:*Interglandular ulceration
:*Hyperemia
:*Thickened mucosa
:*Reactive glandular hyperplasia
:*Stromal edema
:*Infiltration of neutrophils, eosinophils, and macrophages
:*Lymphoid aggregates
:*Detection of amebas on surface exudate
:*Tissue necrosis, usually fibrinoid (advanced lesion)
:*Formation of granulation tissue (advanced lesion)


==Gallery==
==Gallery==

Revision as of 17:55, 10 March 2016

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Yazan Daaboul, M.D.; Serge Korjian M.D.

Overview

Pathophysiology

Transmission

  • E. histolytica cyst is usually transmitted by the fecal-oral route through contaminated drinking water or food)
  • E. histolytica cyst may also be transmitted indirectly through direct contact with infected individuals.

Pathogenesis

  • Following transmission, E. histolytica trophozoites inhabit in the large intestine of the human host.
  • In the large intestine, the trophozoite invades the intestinal mucosa into the blood stream. Simultaneously, they form resistant cysts that are then excreted in human stools.
  • Once in the bloodstream, the trophozoite migrates into the portal circulation and develops amebic liver abscess.

Invasion of Intestinal Mucosa

  • E. histolytica trophozoites secrete proteases, which induce the release of mucin from goblet cells, resulting in glandular hyperplasia.
  • E. histolytica is

Gross Pathology

On gross pathology, the following findings may be present in patients with amebiasis:

  • Wavy surface epithelium (results from focal release of mucin and spasm of the muscular layer)
  • Nodular and/or irregular ulcers in the cecum (most common), sigmoid colon, and rectum. Early ulcers are usually in the interglandular epithelium.
  • Nodular: small (sub-centrimetric), rounded, elevated lesions with necrotic center and edematous rim
  • Irregular: large (1-5 cm), shallow with broad elevated margins

Note: the mucosal folds may occasionally hide small colonic ulcers (false-negative results)

Microscopic Pathology

  • On microscopic pathology, amebiasis is characterized by a flask ulcer (deep, microhemorrhagic ulceration involving the submucosa), which is a characteristic of advanced disease.
  • Additional findings may be present in patients with amebiasis:
  • Interglandular ulceration
  • Hyperemia
  • Thickened mucosa
  • Reactive glandular hyperplasia
  • Stromal edema
  • Infiltration of neutrophils, eosinophils, and macrophages
  • Lymphoid aggregates
  • Detection of amebas on surface exudate
  • Tissue necrosis, usually fibrinoid (advanced lesion)
  • Formation of granulation tissue (advanced lesion)

Gallery

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 "Public Health Image Library (PHIL)".


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