Entamoeba Histolytica: Clinical Manifestations

Ans. is `a’ i.e., Man

Ans. is ‘c’ i.e., Vertical transmission

.        The cystic form (cyst) is the infective form of E. histolytica.

.        Most of transmission are :-

i) Feco oral route :‑

–   This may readily take place through intake of contaminate water or food.

–      Amoebiasis occur when parasites are taken in by the mouth.

ii) Sexual transmission :‑

–       Sexual transmission by oral- rectal contact is also recognised. In developing countries transmission of E. histolytica mainly occurs as a result of low standards of hygiene but in western countries where the incidence of amoebiasis is low, transmission by sexual contact is important.

iii) Transmission through vectors ( Parija 3rd/e p 39) :

–  Vectors such as flies, cockroaches and rodents are capable of carrying cysts and contaminated food & drink.

Ans. is ‘b’ i.e., Liver

Liver abscess is the most common extra-intestinal manifestation of amoebiasis.

Ans. is ‘d’ i.e., The infection reaches the skin through the blood stream

.  Skin is involved directly over the region adjoining a visceral lesion, such as, in the areas of drainage of liver abscess or colostomy wound, in the sites of ruptured appendicular and peri-colic abscesses.

.  Extensive necrosis and sloughing of the skin and subcutaneous tissues are caused by the trophozoites of E. histolytica.

.  Granulomatous ulceration and granulomatous mass may occur in the peri-anal region.

Ans. is ‘b’ i.e., Caecum & ‘c’ i.e., Ascending colon

• E. histolytica forms flask shaped ulcers.

o Amebiasis most frequently involves the cecum and ascending colon, followed in order by the sigmoid, rectum, and appendix.

Ans. is ‘c’ i.e., Abscess due to suppuration

Amebic liver abscess

o Pus in amoebic liver abscess is not due to suppuration, but is a mixture of sloughed liver tissue and blood. o It is chocolate brown in colour and thick in consistency (anchovy sauce pus)

o In the tropics 2-10% of the individuals infected with entamoeba histolytica suffer from hepatic complications. The trophozoites are carried from the large intestine to the liver by portal vein. In the liver the capillary system acts as efficient filter and holds these parasites.

o In case of amoebic liver abscess the diagnostic aspiration is done from the abscess wall because the trophozoites are confined to the periphery.

Ans. is ‘a’ i.e., Flask shaped; ‘b’ i.e., Undermined edges

o Amebiasis most frequently involves the cecum and ascending colon, followed in order by the sigmoid, rectum and appendix.

o The ulcerative lesions develop undermining of margins of the ulcer due to lytic action of the trophozoites.

o Ulcer has a flask shaped with a narrow neck and broad base.

Answer is ‘b’ Most common in right lobe liver; ‘c’ Can rupture into pleural cavity

Amoebic Liver abscess

• Caused by Entamoeba histolytica whose cysts are acquired through the feco-oral route and their trophozoites reach the liver through portal venous system.
• Like pyogenic abscess they are also common in rt. lobe of liver.
• Clinical Picture

– the typical clinical picture is of a patient 20-40 yrs of age who has travelled to an endemic area, presents with fever, chills, anorexia, rt. upper quadrant pain.

– although liver abscess results from an obligatory colonic infection, a recent history of diarrhoea is uncommon.

– jaundice is rare. (c.f. in pyogenic abscess jaundice is seen in —25% of pts.)

• Liver function tests may show mild abnormalities, hyperbilirubinemia is uncommon.
• CT > U/S are the mainstay of investigation.
• Diagnosis is confirmed by serological tests (enzyme immuno assay) for antiamoebic antibodies.
• Cultures of amoebic abscess are usually negative.
• Treatment
• Metronidazole is the mainstay of t/t and is curative in over 90% of patients.(other nitroimidazoles i.e. secnidazole, tinidazole, are also effective)
• Therapeutic needle aspiration is avoided. Done only when

– pt. fails to respond to metronidazole

– high risk of rupture

– abscess secondarily infected with pyogenic organism.

• Complications may occur uncommonly; these are

– rupture into the peritoneum, pleural cavity or pericardium.

Ans is a i.e. More common in females & b i.e. More common in left lobe of liver 

Ans. is ‘c>b’ i.e., Surgical drainage is always indicated > Patient is toxic. 

Answer is B (Direct spread from liver):

An amoebic lung abscess is almost always secondary to spread from the liver.

Extraintestinal infection by E. histolytica most often involves the liver. Further involvement most commonly leads to Amoebic lung abscess.

Infact pleuropulmonary involvement (Lung): is the most frequent complication of Amoebic liver abscess.

Remember:

Most common cause of a lung abscess is – ‘Aspiration’. However this holds true for pyogenic (bacterial lung abscess)

Ans. B: Liver

E histolytica exists in 2 forms. The cyst stage is the infective form, and the trophozoite stage causes invasive disease. People who chronically carry E histolytica shed cysts in their feces; these cysts are transmitted primarily by food and water contamination. Cysts are resistant to gastric acid, but the wall is broken down by trypsin in the small intestine. Trophozoites are released and colonize the cecum. To initiate symptomatic infection, E histolytica trophozoites present in the lumen must adhere to the underlying mucosa and penetrate the mucosal layer.

Liver involvement occurs following invasion of E histolytica into mesenteric venules. Amebae then enter the portal circulation and travel to the liver where they typically form large abscesses.

The abscess contains acellular proteinaceous debris, which is thought to be a consequence of induced apoptosis and is surrounded by a rim of amebic trophozoites invading the tissue.

The right lobe of the liver is more commonly affected than the left lobe. This has been attributed to the fact that the right lobe portal laminar blood flow is supplied predominantly by the superior mesenteric vein, whereas the left lobe portal blood flow is supplied by the splenic vein.

Ans. B: Pleural

Pleuropulmonary infection is the most common complication.

Mechanisms of infection include development of a sympathetic serous effusion; rupture of a liver abscess into the chest cavity, leading to empyema; or hematogenous spread, resulting in parenchymal infection.

Cardiac involvement results following the rupture of an abscess involving the left lobe of the liver. It usually is associated with very high mortality.

Intraperitoneal rupture occurs in 2-7% of patients. Left lobe abscesses are more likely to progress to rupture because of their later clinical presentation

Ans: B i.e. Serum Entamoeba antibodies

• Analysis of serum for Entamoeba antibodies by immunoassay carries 99% sensitivity and more than 90% specificity, and is more accurate than stool analysis in amoebic liver disease
• Diagnosis may depend on cyst aspiration revealing the classic anchovy sauce appearance of the cyst fluid

Ans. B: Alcoholics are susceptible to develop amoebic liver abscess

The right lobe (posterior superior quadrant) of the liver is more commonly affected than the left lobe. This has been attributed to the fact that the right lobe is supplied predominantly by the superior mesenteric vein, whereas the left lobe is supplied by the splenic vein.

Histologic Findings of abscess

The abscess contains acellular proteinaceous debris and is surrounded by a rim of amebic trophozoites invading tissue. The abscess contains a chocolate-colored fluid that resembles anchovy paste and consists predominantly of necrotic hepatocytes.

Complications

• Pleuropulmonary infection is the most common complication.
• Cardiac involvement results following the rupture of an abscess involving the left lobe of the liver. It usually is associated with very high mortality.
• Intraperitoneal rupture occurs in 2-7% of patients. Left lobe abscesses are more likely to progress to rupture because of their later clinical presentation.
• Bacterial superinfection can occur.