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Entamoeba Histolytica Overview
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Entamoeba Histolytica Overview

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Questions and Answers

Where are liver abscesses usually located in cases of hepatic amoebiasis?

  • Lower right lobe
  • Upper right lobe (correct)
  • Upper left lobe
  • Lower left lobe

    • What is a common complication of untreated liver abscesses?

  • Chronic abscess formation in the intestine
  • Complete recovery without intervention
  • Formation of new abscesses in the liver
  • Rupture into the diaphragm (correct)

    • Which of the following is a luminal amoebicide used for treating amoebic infections?

  • Metronidazole
  • Emetine
  • Diloxanide furoate (correct)
  • Chloroquine

    • In the treatment of amoebic liver abscess, what is the initial dosage of chloroquine recommended?

    <p>1 g for 2 days</p> Signup and view all the answers

    What is a critical measure for the prophylaxis of hepatic amoebiasis?

    <p>Protection of food and water from fecal contamination</p> Signup and view all the answers

    What characterizes the mature cyst of E. histolytica?

    <p>Contains four nuclei</p> Signup and view all the answers

    In what part of the ileum does excystation of E. histolytica occur?

    <p>Lower ileum</p> Signup and view all the answers

    Which staining method shows nuclear chromatin and chromatoid bodies appearing deep blue or black?

    <p>Iron hemotoxylin stain</p> Signup and view all the answers

    Which stage of E. histolytica is characterized by amoeboid movements and liberation of quadrinucleate amoeba?

    <p>Metacyst stage</p> Signup and view all the answers

    What role does the lytic enzyme histolysin play in E. histolytica pathogenesis?

    <p>Damages mucosal epithelium</p> Signup and view all the answers

    What is the typical lesion seen in intestinal amoebiasis?

    <p>Ulcer</p> Signup and view all the answers

    What is the primary form of transmission for E. histolytica?

    <p>Consumption of contaminated food and water</p> Signup and view all the answers

    What outcome does the invasion of metacystic trophozoites typically lead to in the colon?

    <p>Development of abscesses and ulcers</p> Signup and view all the answers

    Which protozoan is known to cause amoebic dysentery and is prevalent in tropical regions?

    <p>Entamoeba histolytica</p> Signup and view all the answers

    What is the average size of a trophozoite of Entamoeba histolytica?

    <p>20 μm</p> Signup and view all the answers

    At what temperature can trophozoites of Entamoeba histolytica survive for a limited time?

    <p>37°C</p> Signup and view all the answers

    Which of the following statements is TRUE regarding the trophozoites of Entamoeba histolytica?

    <p>They may contain phagocytosed erythrocytes.</p> Signup and view all the answers

    In which stage does Entamoeba histolytica undergo a transformation to form a cyst?

    <p>Precystic stage</p> Signup and view all the answers

    What is a distinguishing feature of trophozoites in acute dysentery compared to other intestinal amoebae?

    <p>Containment of phagocytosed RBCs</p> Signup and view all the answers

    Which cystic stage is identifiable as having a defined cyst wall?

    <p>Mature cyst</p> Signup and view all the answers

    What is the spherical size range of a cyst of Entamoeba histolytica?

    <p>10-20 μm</p> Signup and view all the answers

    What is the typical shape of an amoebic ulcer in cross section?

    <p>Flask-shaped</p> Signup and view all the answers

    How far do the ulcers typically extend into the intestinal wall?

    <p>To the submucosal layer</p> Signup and view all the answers

    What is a common characteristic of the stools in typical amoebic dysentery?

    <p>Large and foul-smelling with blood-streaked mucus</p> Signup and view all the answers

    What complication may arise from chronic involvement of the caecum due to amoebic infection?

    <p>Simulated appendicitis</p> Signup and view all the answers

    What type of abscess may occur in about 5-10% of patients with intestinal amoebiasis?

    <p>Liver abscess</p> Signup and view all the answers

    What does the center of a hepatic amoebic abscess typically contain?

    <p>Thick chocolate brown pus</p> Signup and view all the answers

    Which clinical feature is typically seen in patients with fulminant colitis due to amoebic infection?

    <p>Febrile and toxic state</p> Signup and view all the answers

    What is the incubation period variability range for intestinal amoebiasis?

    <p>1–4 months</p> Signup and view all the answers

    Liver abscesses in hepatic amoebiasis are most commonly found in the upper left lobe of the liver.

    <p>False</p> Signup and view all the answers

    Chocolate brown sputum is a characteristic symptom in pulmonary amoebiasis due to hepatobronchial fistula.

    <p>True</p> Signup and view all the answers

    Chloroquine is the preferred luminal amoebicide for treating amoebic liver abscess.

    <p>False</p> Signup and view all the answers

    The incidence of liver abscess is more common in women compared to men.

    <p>False</p> Signup and view all the answers

    Both luminal and tissue amoebicides can effectively treat amoebic colitis and amoebic liver abscess.

    <p>True</p> Signup and view all the answers

    Entamoeba histolytica is primarily found in temperate climate regions.

    <p>False</p> Signup and view all the answers

    The trophozoite stage of Entamoeba histolytica divides by binary fission approximately every 8 hours.

    <p>True</p> Signup and view all the answers

    Cysts of Entamoeba histolytica are oval in shape and typically measure 20–30 μm in size.

    <p>False</p> Signup and view all the answers

    The outer ectoplasm of a trophozoite is typically granular in appearance.

    <p>False</p> Signup and view all the answers

    Phagocytosed erythrocytes in trophozoites are a diagnostic feature specific to Entamoeba histolytica.

    <p>True</p> Signup and view all the answers

    Trophozoites can initiate infections if they survive in the stomach after being ingested.

    <p>False</p> Signup and view all the answers

    Entamoeba histolytica is the fourth leading cause of parasitic mortality after malaria, schistosomiasis, and leishmaniasis.

    <p>False</p> Signup and view all the answers

    The average size of a trophozoite of Entamoeba histolytica is around 30 μm.

    <p>False</p> Signup and view all the answers

    The early cyst of E.histolytica contains four nuclei.

    <p>False</p> Signup and view all the answers

    Excystation occurs in the duodenum after the cyst wall is damaged by trypsin.

    <p>False</p> Signup and view all the answers

    With iodine stain, chromatoid bodies appear bright yellow.

    <p>False</p> Signup and view all the answers

    The typical amoebic ulcer in intestinal amoebiasis does not extend deeper than the muscular layer.

    <p>False</p> Signup and view all the answers

    The optimal habitat for metacystic trophozoites is in the mucosal tissue of the stomach.

    <p>False</p> Signup and view all the answers

    In hepatic amoebiasis, the center of the abscess is filled with thick yellow pus.

    <p>False</p> Signup and view all the answers

    The incubation period for amoebiasis is always 4 days.

    <p>False</p> Signup and view all the answers

    Patients with intestinal amoebiasis are typically febrile and toxic.

    <p>False</p> Signup and view all the answers

    Amoebic dysentery is characterized by small, odorless stools that contain mucus.

    <p>False</p> Signup and view all the answers

    Amoebic ulcers are characteristically solitary and confined to the rectum.

    <p>False</p> Signup and view all the answers

    The incubation period for intestinal amoebiasis can vary between 1 week and 4 months.

    <p>False</p> Signup and view all the answers

    Metacystic trophozoites undergo division to form eight nuclei, each surrounded by cytoplasm.

    <p>True</p> Signup and view all the answers

    Histolysin is a protective enzyme that enhances the healing of ulcers caused by E.histolytica.

    <p>False</p> Signup and view all the answers

    The ulcers in intestinal amoebiasis can lead to strictures and thickening of the gut wall.

    <p>True</p> Signup and view all the answers

    Only about 1% of individuals with intestinal amoebiasis develop liver abscesses.

    <p>False</p> Signup and view all the answers

    Chronic involvement of the caecum due to amoebic infection can present symptoms resembling appendicitis.

    <p>True</p> Signup and view all the answers

    What are the three forms of Entamoeba histolytica?

    <p>Trophozoite, Precyst, and Cyst.</p> Signup and view all the answers

    What characteristic distinguishes the trophozoites of Entamoeba histolytica found in dysenteric stools?

    <p>They often contain phagocytosed erythrocytes.</p> Signup and view all the answers

    At what temperature can trophozoites of Entamoeba histolytica survive, and how long do they live at that temperature?

    <p>They can survive at 37°C for up to 5 hours.</p> Signup and view all the answers

    What occurs during the encystment of trophozoites in Entamoeba histolytica?

    <p>Trophozoites extrude their food vacuoles and become round or oval, secreting a cyst wall.</p> Signup and view all the answers

    What is the range of sizes (in μm) for a mature cyst of Entamoeba histolytica?

    <p>The cyst measures about 10–20 μm in size.</p> Signup and view all the answers

    How often do trophozoites of Entamoeba histolytica divide by binary fission?

    <p>They divide every 8 hours.</p> Signup and view all the answers

    What is a notable feature of the endoplasm of the trophozoite stage of Entamoeba histolytica?

    <p>It has a finely granular appearance with a ground glass texture.</p> Signup and view all the answers

    Why are live trophozoites not transmitted through stool ingestion in Entamoeba histolytica infections?

    <p>They are rapidly destroyed in the stomach and cannot initiate infection.</p> Signup and view all the answers

    What is the expected outcome if untreated liver abscesses in hepatic amoebiasis rupture?

    <p>Untreated liver abscesses may rupture into adjacent tissues such as the lungs, pleural cavity, pericardium, or abdominal wall.</p> Signup and view all the answers

    Describe the characteristics of the sputum produced in cases of pulmonary amoebiasis.

    <p>The sputum is typically chocolate brown and results from a hepatobronchial fistula.</p> Signup and view all the answers

    How do luminal amoebicides differ from tissue amoebicides in the treatment of amoebic infections?

    <p>Luminal amoebicides act in the intestinal lumen, while tissue amoebicides are effective in systemic infection but not in the intestine.</p> Signup and view all the answers

    What population is at a lower risk for developing liver abscesses in the context of hepatic amoebiasis?

    <p>The incidence of liver abscesses is less common in women and rare in children under 10 years of age.</p> Signup and view all the answers

    What role does health education play in the prophylaxis of hepatic amoebiasis?

    <p>Health education promotes healthy personal habits and prevents contamination of food and water.</p> Signup and view all the answers

    What is the characteristic appearance of the typical amoebic ulcer in cross section?

    <p>It is flask-shaped with a narrow mouth and neck, and a large rounded base.</p> Signup and view all the answers

    In cases of fulminant colitis, how does the clinical presentation differ from typical intestinal amoebiasis?

    <p>Patients are febrile and toxic, displaying confluent ulceration and necrosis of the colon.</p> Signup and view all the answers

    What type of pus is commonly found in the center of a hepatic amoebic abscess?

    <p>The center contains thick chocolate brown pus, often referred to as 'anchovy sauce pus'.</p> Signup and view all the answers

    Describe the typical stool characteristics associated with amoebic dysentery.

    <p>The stools are large, foul-smelling, brownish black, often mixed with bloodstreaked mucus.</p> Signup and view all the answers

    What complications can arise from chronic involvement of the cecum due to amoebic infection?

    <p>It can lead to conditions mimicking appendicitis and the formation of strictures or partial obstruction.</p> Signup and view all the answers

    During the incubation period of intestinal amoebiasis, what symptomatology is generally observed?

    <p>The clinical course is characterized by prolonged latency, relapses, and intermissions.</p> Signup and view all the answers

    How can amoebic granulomas be misdiagnosed, and why is this significant?

    <p>Amoebic granulomas may be mistaken for malignant tumors, leading to inappropriate treatment.</p> Signup and view all the answers

    What role do lysosomal enzymes and cytokines play in hepatic amoebiasis?

    <p>They likely contribute to liver damage rather than the amoebae directly causing it.</p> Signup and view all the answers

    What structural change occurs to the cyst wall during excystation in E. histolytica?

    <p>The cyst wall gets damaged by trypsin, leading to excystation.</p> Signup and view all the answers

    What is the role of the histolysin enzyme in the pathogenesis of E. histolytica?

    <p>Histolysin facilitates the penetration of trophozoites into the colonic epithelium, causing tissue damage.</p> Signup and view all the answers

    Describe the typical appearance of amoebic ulcers in intestinal amoebiasis.

    <p>Amoebic ulcers appear as multiple lesions confined to the colon, with raised nodules and pouting edges.</p> Signup and view all the answers

    What distinguishes the metacystic trophozoite stage from the earlier cyst stage of E. histolytica?

    <p>Metacystic trophozoites exhibit amoeboid movements and have four nuclei that can further divide.</p> Signup and view all the answers

    Which part of the gastrointestinal tract is optimal for the survival of metacystic trophozoites?

    <p>The submucosal tissue of the caecum and colon is optimal for metacystic trophozoites.</p> Signup and view all the answers

    How does the staining with iron hemotoxylin assist in identifying E. histolytica?

    <p>Iron hemotoxylin stain colors nuclear chromatin and chromatoid bodies deep blue or black.</p> Signup and view all the answers

    What impact does the motility of trophozoites have on the severity of intestinal amoebiasis?

    <p>The motility enhances their ability to penetrate host tissues, leading to severe damage and necrosis.</p> Signup and view all the answers

    How does the lifecycle of E. histolytica complete its transmission cycle?

    <p>Cysts are passed in feces and can contaminate food and water, leading to infection in new hosts.</p> Signup and view all the answers

    Entamoeba histolytica is the third leading parasitic cause of mortality, after malaria and ______.

    <p>schistosomiasis</p> Signup and view all the answers

    The trophozoite is the only form of Entamoeba histolytica present in ______.

    <p>tissues</p> Signup and view all the answers

    The cyst of Entamoeba histolytica is approximately ______ μm in size.

    <p>10–20</p> Signup and view all the answers

    Trophozoites divide by ______ fission approximately every 8 hours.

    <p>binary</p> Signup and view all the answers

    The trophozoites from acute dysenteric stools often contain phagocytosed ______.

    <p>erythrocytes</p> Signup and view all the answers

    Entamoeba histolytica undergoes ______ in the intestinal lumen before forming a cyst.

    <p>encystment</p> Signup and view all the answers

    The outer ectoplasm of a trophozoite is clear, transparent, and ______.

    <p>refractile</p> Signup and view all the answers

    Typical amoeboid motility is a crawling or ______ movement, not a free swimming one.

    <p>gliding</p> Signup and view all the answers

    The mature cyst of E.histolytica is characterized as being ______

    <p>quadrinucleate</p> Signup and view all the answers

    E.histolytica passes its life cycle only in ______

    <p>man</p> Signup and view all the answers

    The optimal habitat for the metacystic trophozoite is the submucosal tissue of the ______ and colon

    <p>caecum</p> Signup and view all the answers

    Excystation occurs when the cyst reaches the lower part of the ______

    <p>ileum</p> Signup and view all the answers

    Penetration of the amoeba is facilitated by motility and the tissue lytic enzyme, ______

    <p>histolysin</p> Signup and view all the answers

    The cysts pass through the stomach ______ and enter the small intestine

    <p>undamaged</p> Signup and view all the answers

    Amoebic ulcers typically appear initially as raised nodules with ______ edges

    <p>pouting</p> Signup and view all the answers

    The average incubation period for amoebiasis ranges from ______ to 4 months

    <p>4 days</p> Signup and view all the answers

    Liver abscesses are usually located in the upper right lobe of the ______.

    <p>liver</p> Signup and view all the answers

    A hepatobronchial fistula may result in expectoration of ______ brown sputum.

    <p>chocolate</p> Signup and view all the answers

    Luminal amoebicides act in the intestinal lumen but not in ______.

    <p>tissues</p> Signup and view all the answers

    Metronidazole is the drug of choice for treating both amoebic colitis and amoebic liver ______.

    <p>abscess</p> Signup and view all the answers

    General prophylaxis for hepatic amoebiasis includes protecting food and water from ______ with human excreta.

    <p>contamination</p> Signup and view all the answers

    The typical amoebic ulcer is ______-shaped in cross section.

    <p>flask</p> Signup and view all the answers

    In chronic amoebic infections, the ______ of the gut wall may occur.

    <p>thickening</p> Signup and view all the answers

    The ulcers in intestinal amoebiasis do not extend deeper than the ______ layer.

    <p>submucosal</p> Signup and view all the answers

    The stools in typical amoebic dysentery are large, foul-smelling, and often ______ with bloodstreaked mucus.

    <p>brownish black</p> Signup and view all the answers

    Hepatic amoebiasis may lead to the formation of liver ______.

    <p>abscesses</p> Signup and view all the answers

    The center of a hepatic amoebic abscess contains thick ______ pus.

    <p>chocolate brown</p> Signup and view all the answers

    The patient with fulminant colitis often presents as ______ and toxic.

    <p>febrile</p> Signup and view all the answers

    The incubation period for intestinal amoebiasis is highly variable, ranging from 1 to ______ months.

    <p>4</p> Signup and view all the answers

    Match the following amoebicides with their classification:

    <p>Diloxanide furoate = Luminal amoebicide Emetine = Tissue amoebicide Metronidazole = Both luminal and tissue amoebicide Iodoquinol = Luminal amoebicide</p> Signup and view all the answers

    Match the following clinical features with their corresponding conditions:

    <p>Expectoration of chocolate brown sputum = Pulmonary amoebiasis Severe pleuritic chest pain and dyspnea = Pulmonary amoebiasis Rupture into the pleural cavity = Untreated liver abscess Jaundice due to multiple lesions = Hepatic amoebiasis</p> Signup and view all the answers

    Match the following treatment dosages with the respective drug:

    <p>1 g for 2 days followed by 5 g daily for 3 weeks = Chloroquine in amoebic liver abscess Acts in the intestinal lumen but not in tissues = Luminal amoebicides Effective in systemic infection but less in the intestine = Tissue amoebicides Drugs of choice for amoebic colitis = Metronidazole and related compounds</p> Signup and view all the answers

    Match the following preventive measures with their descriptions:

    <p>Protecting food and water from contamination = General prophylaxis for fecal-oral infections Exclusion from food handling occupations = Detection and treatment of carriers Health education = Limiting the spread of infection Healthy personal habits = Control of hepatic amoebiasis spread</p> Signup and view all the answers

    Match the following statements with their accuracy:

    <p>Liver abscess is less common in women = True Untreated liver abscesses typically resolve spontaneously = False Amoebic empyema develops frequently = False Chloroquine is a preferred luminal amoebicide = False</p> Signup and view all the answers

    Match the stages of Entamoeba histolytica with their characteristics:

    <p>Early cyst = Contains a single nucleus and two chromatid bars Mature cyst = Contains 4 nuclei 'quadrinucleate' Metacystic trophozoite = Capable of amoeboid movements Excystation = Occurs in the lower part of the ileum</p> Signup and view all the answers

    Match the staining methods with their observed results:

    <p>Iron hemotoxylin stain = Nuclear chromatin and chromatoid bodies appear deep blue or black Iodine stain = Nuclear chromatin and karyosome appear bright yellow Hemotoxylin stain = Cysts appear colorless Giemsa stain = Nuclei are stained red</p> Signup and view all the answers

    Match the forms of amoebiasis with their descriptions:

    <p>Intestinal amoebiasis = Causes discrete ulcers in the colon Extraintestinal amoebiasis = Can lead to abscess formation in organs like the liver Asymptomatic amoebiasis = Patients show no clinical symptoms despite cyst presence Fulminant amoebiasis = Presents rapid and severe symptoms</p> Signup and view all the answers

    Match the life cycle stages of E. histolytica with their respective roles:

    <p>Mature quadrinucleate cyst = Infective form of the parasite Metacystic trophozoite = Grows and penetrates the intestinal walls Cyst = Passed in feces to continue the cycle Excystation = Initiates the transition from cyst to trophozoite</p> Signup and view all the answers

    Match the pathological effects of E. histolytica with their outcomes:

    <p>Mucosal penetration = Produces ulcerative lesions Histolysin activity = Causes lytic necrosis Amoebic dysentery = Characterized by bloody diarrhea Cyst formation = Protection for parasites during unfavorable conditions</p> Signup and view all the answers

    Match the characteristics of cysts found in E. histolytica with their details:

    <p>Size range = 20–30 μm in diameter Shape = Oval Stage identification = Defined cyst wall Presence of nuclei = Typically quadrinucleate in mature stage</p> Signup and view all the answers

    Match the incubation periods with their respective durations:

    <p>Amoebiasis = 4 days to 4 months Fulminant colitis = Typically shorter than standard amoebiasis Asymptomatic infection = May have a prolonged incubation Acute dysentery = Manifestation often occurs within 1-2 weeks</p> Signup and view all the answers

    Match the transmission methods with their mechanisms:

    <p>Ingestion of contaminated food = Primary route of infection Water contamination = Common source of cysts Direct fecal contact = Less common but possible route Aerosol transmission = Not applicable for E. histolytica</p> Signup and view all the answers

    Match the amoebic diseases with their related clinical features:

    <p>Intestinal Amoebiasis = Large foul-smelling stools with blood-streaked mucus Hepatic Amoebiasis = Enlarged tender liver without detectable liver function impairment Pulmonary Amoebiasis = Chocolate brown sputum due to hepatobronchial fistula Cutaneous Amoebiasis = Skin lesions due to amoebic infection</p> Signup and view all the answers

    Match the specific features with the type of amoebic infection:

    <p>Flask-shaped ulcer = Intestinal Amoebiasis Thick chocolate brown pus = Hepatic Amoebiasis Strictures and partial obstruction = Chronic intestinal involvement Foul-smelling diarrhea = Amoebic dysentery</p> Signup and view all the answers

    Match the symptoms with their respective amoebic conditions:

    <p>Confluent ulceration and necrosis of colon = Fulminant Colitis Vague abdominal symptoms and discomfort = Uncomfortable belly Clumped reddish-brown RBCs in stools = Typical intestinal amoebiasis Febrile and toxic state = Severe amoebic infection</p> Signup and view all the answers

    Match the abscess characteristics with their corresponding type of amoebiasis:

    <p>Liver abscess = Hepatic Amoebiasis Pulmonary abscess = Pulmonary Amoebiasis Cutaneous lesions = Cutaneous Amoebiasis Urinary tract lesions = Genitourinary Amoebiasis</p> Signup and view all the answers

    Match the incubation periods with their corresponding amoebic infections:

    <p>1 month = Intestinal Amoebiasis 2 months = Chronic symptoms in Intestinal Amoebiasis 3 months = Fulminant Colitis onset 4 months = Prolonged latency phase</p> Signup and view all the answers

    Match the amoebic ulcer characteristics with their descriptions:

    <p>Mouth and neck narrow = Flask-shaped ulcer Base large and rounded = Typical amoebic ulcer Submucosal spread = Amoebiasis characteristic Extensive undermining = Lateral spread of amoebae</p> Signup and view all the answers

    Match the following stages of Entamoeba histolytica with their descriptions:

    <p>Trophozoite = The vegetative or growing stage of the parasite, irregular in shape. Precyst = Stage where trophozoite becomes round or oval with a glycogen vacuole. Cyst = Spherical form about 10-20 μm in size with a defined cyst wall. Mature cyst = Contains two chromatid bars and is the result of encystment.</p> Signup and view all the answers

    Match the amoebic manifestations with their clinical importance:

    <p>Necrotic material containing trophozoites = Amoebic infection diagnosis Chronic gut wall thickening = Potential for obstruction Patchy mucosal loss = Extension of ulcerative process Liver damage from inflammatory response = Indirect effect of amoebic presence</p> Signup and view all the answers

    Match the types of amoebic infections with their associated complications:

    <p>Hepatic Amoebiasis = Liver abscess formation Pulmonary Amoebiasis = Respiratory symptoms Genitourinary Amoebiasis = Urinary tract issues Intestinal Amoebiasis = Dysentery and diarrhea</p> Signup and view all the answers

    Match the following characteristics with the correct forms of Entamoeba histolytica:

    <p>Trophozoite = Contains phagocytosed erythrocytes, diagnostic feature. Cyst = Spherical shape, capable of surviving outside the host. Precyst = State before encystment, has a large glycogen vacuole. Mature cyst = Ready for excystation, with a complete cyst wall.</p> Signup and view all the answers

    Match the following terms related to Entamoeba histolytica with their meanings:

    <p>Amoebic dysentery = Severe intestinal infection caused by E. histolytica. Binary fission = Method of division for trophozoites every 8 hours. Encystment = Process of forming a cyst from a trophozoite. Erythrophagocytosis = The process of trophozoites ingesting red blood cells.</p> Signup and view all the answers

    Match the following descriptions of Entamoeba histolytica with their corresponding forms:

    <p>Trophozoite = Motile form present in tissues, grows in intestine. Precyst = Form that has just extruded its food vacuoles. Cyst = Form that can be ingested and leads to infection. Mature cyst = Prepared form that is resistant to adverse conditions.</p> Signup and view all the answers

    Match the following diseases with their causative form of Entamoeba histolytica:

    <p>Amoebic dysentery = Infection characterized by severe diarrhea. Amoebic liver abscess = Infection marked by abscess formation in liver. Intestinal amoebiasis = General term for intestinal infection by E. histolytica. Pulmonary amoebiasis = Rare infection linked to spread from liver to lungs.</p> Signup and view all the answers

    Match the following features with the correct stage of Entamoeba histolytica:

    <p>Trophozoite = Average size approximately 20 μm. Cyst = Resistant to drying, heat, and harsh environments. Precyst = Form not found outside the intestinal lumen. Mature cyst = Form likely ingested for potential infection.</p> Signup and view all the answers

    Match the following terms with their specific characteristics concerning Entamoeba histolytica:

    <p>Amoeboid motility = Crawling or gliding movement rather than free swim. Pseudopodia = Finger-like projections aiding movement. Karyosome = Central structure found in the nucleus of trophozoites. Glycogen vacuole = Large storage structure in the precyst form.</p> Signup and view all the answers

    Match the following components of the life cycle of Entamoeba histolytica with their functions:

    <p>Trophozoite = Invades tissues and causes disease. Cyst = Facilitates transmission in host environments. Precyst = Transition stage for the formation of a mature cyst. Mature cyst = Resistant to harsh conditions, crucial for infection.</p> Signup and view all the answers

    Study Notes

    Entamoeba Histolytica

    • Entamoeba histolytica is a protozoan parasite that causes amoebic dysentery and amoebic liver abscess.
    • The parasite is found worldwide but is more common in tropical regions.
    • It's estimated that 10% of the global population and 50% of people in developing countries are infected with the parasite.
    • E. histolytica is a leading cause of parasitic mortality, ranking third after malaria and schistosomiasis.

    Morphology

    • E. histolytica exists in three forms: trophozoite, precystic stage, and cyst.
    • The trophozoite is the vegetative or active form of the parasite.
    • It's the only form present in tissues, ranging in size from 12-60 µm with an average of 20 µm.
    • Trophozoites are characterized by their irregular shape and amoeboid movement.
    • They have a clear outer ectoplasm and a finely granular inner endoplasm.
    • Trophozoites in acute dysenteric stool often contain ingested red blood cells (RBCs), which is a diagnostic feature.
    • Trophozoites divide by binary fission (splitting into two) every 8 hours.
    • They can survive for up to 5 hours at 37°C and are killed by drying, heat, and chemical sterilization.
    • Infection is not transmitted by trophozoites because they cannot survive outside the body to initiate infection.
    • The precystic stage is a transition phase where the trophozoite prepares for encystment.
    • The cyst is the spherical, dormant form of the parasite.
    • It's 10-20 µm in size and can contain one to four nuclei.

    Life Cycle

    • E. histolytica completes its life cycle solely in humans.
    • The mature cyst with four nuclei is the infective stage.
    • Infection occurs when humans ingest food or water contaminated with cysts.
    • Cysts survive passage through the stomach and reach the small intestine, where excystation occurs.
    • During excystation, the cyst wall breaks down due to trypsin.
    • The liberated quadrinucleate amoeba then divides into eight smaller metacystic trophozoites.
    • These trophozoites are found in the submucosal tissue of the caecum and colon.
    • Some metacystic trophozoites develop into precystic forms and cysts.
    • Cysts are passed in feces, completing the cycle.

    Pathogenesis

    • E. histolytica can cause both intestinal and extraintestinal amoebiasis.
    • The incubation period is highly variable, typically ranging from four days to four months.
    • Symptoms and severity depend on the organ affected and the extent of damage.

    Intestinal Amoebiasis

    • Metacystic trophozoites penetrate the colon's epithelial lining.
    • Penetration is aided by the amoeba's motility and the enzyme "histolysin," which damages the mucosal cells.
    • Amoeba penetration creates distinctive ulcers with a pinhead center and raised edges.
    • Amoebic ulcers are the characteristic lesion of intestinal amoebiasis.
    • Ulcers are often multiple and concentrated in the caecum and sigmoidorectal region.
    • The ulcers can undermine and spread laterally, causing extensive mucosal loss.
    • Occasionally, ulcers penetrate deeper into the colon wall, leading to perforation and peritonitis.
    • Deep ulcers can form scars that constrict the colon, leading to obstruction.
    • These amoebic granulomas can be mistaken for malignant tumors.

    Clinical Features

    • Amoebic dysentery is the typical manifestation of intestinal amoebiasis.
    • Patients experience large, foul-smelling, bloody stools with mucus.
    • The stools contain clumped, reddish-brown RBCs.
    • Trophozoites with ingested RBCs can be observed in the stool.
    • Patients are usually afebrile (not feverish) and nontoxic.
    • Fulminant colitis (acute inflammation of the colon) causes confluent ulceration and necrosis.
    • Other intestinal symptoms like diarrhea or vague abdominal discomfort can occur.
    • Chronic involvement of the caecum can mimic appendicitis.

    Extraintestinal Amoebiasis

    • E. histolytica can spread beyond the intestines and cause complications in other organs.
    • The most common extraintestinal complication is hepatic amoebiasis, which can lead to liver abscesses.
    • Pulmonary amoebiasis can occur due to the spread of liver abscesses to the lungs.
    • Metastatic amoebiasis can involve other organs like the brain, skin, and genitourinary tract.

    Hepatic Amoebiasis

    • Liver damage might not be directly caused by amoeba but by enzymes and inflammatory mediators released by surrounding cells.
    • Liver abscesses are present in about 5%-10% of patients with intestinal amoebiasis.
    • Abscesses typically occur in the upper right lobe of the liver and contain thick, chocolate-brown pus.
    • Abscesses can rupture into surrounding tissues, causing complications depending on the location.
    • Liver abscesses are less common in women and rare in children under 10 years old.

    Pulmonary Amoebiasis

    • Pulmonary amoebiasis often results from a hepatobronchial fistula and can lead to amoebic empyema.
    • Patients present with chest pain, dyspnea (difficulty breathing), and non-productive coughs.

    Treatment

    • Luminal amoebicides like diloxanide furoate, iodoquinol, paromomycin, and tetracycline target the intestinal lumen but have limited effect on tissue amoebae.
    • Tissue amoebicides such as emetine and chloroquine are effective against systemic infection but less potent against intestinal amoebae.
    • Metronidazole and its related compounds (tinidazole, ornidazole) are the drugs of choice for treating both intestinal and liver involvement.
    • Metronidazole dosage for liver abscess is 1 g for two days, followed by 5 g daily for three weeks.

    Prophylaxis

    • General prophylaxis measures for fecal-oral infections are crucial.
    • Food and water must be protected from contamination with human excreta.
    • Detection and treatment of carriers and their exclusion from food handling jobs help limit infection spread.
    • Healthy personal hygiene practices and education contribute to control efforts.

    Entamoeba Histolytica: A Brief Overview

    • Entamoeba histolytica is responsible for amoebic dysentery and amoebic liver abscess.
    • Its prevalence is widespread, particularly in tropical regions.
    • Around 10% of the global population and 50% of inhabitants in developing countries are estimated to be infected.

    Morphology of Entamoeba Histolytica

    • Entamoeba histolytica exists in three forms: trophozoite, precystic stage, and cyst.
    • Trophozoite: The vegetative or growing stage, present only in tissues.
      • Size: 12–60 μm, averaging 20 μm
      • Active in fresh dysenteric stool, smaller in convalescents and carriers.
      • Cytoplasm: Consists of clear, transparent outer ectoplasm and finely granular inner endoplasm.
      • Motility: Exhibits amoeboid movement, crawling or gliding, driven by pseudopodia.
      • Nucleus: Spherical, 4–6 μm, containing a central karyosome.
      • Important diagnostic feature: Contains phagocytosed erythrocytes, not found in other intestinal amoebae.
      • Divides via binary fission every 8 hours.
      • Survival: Survives for up to 5 hours at 37°C. Killed by drying, heat, and chemical sterilization.
    • Precystic Stage:
      • Forms in the intestinal lumen during encystment.
      • Trophozoites round or oval, extruding food vacuoles.
      • Contains a large glycogen vacuole and two chromatid bars.
      • Secretes a cyst wall, transforming into a cyst.
    • Cystic Stage:
      • Spherical shape, 10–20 μm.
      • Early cyst: Contains a single nucleus and two chromatid bars.
      • Mature cyst: Contains four nuclei, known as a quadrinucleate cyst.
      • Staining:
        • Hematoxylin: Nuclear chromatin and chromatoid bodies appear blue or black.
        • Iodine: Nuclear chromatin and karyosome bright yellow, chromatoid bodies appear clear (unstained).

    The Life Cycle of Entamoeba Histolytica

    • Involves only one host: Humans.
    • Infective form: Mature quadrinucleate cyst.
    • Transmission: Ingestion of contaminated food and water containing cysts.
    • Cysts pass through the stomach unharmed, reaching the small intestine.
    • Excystation: In the lower ileum, trypsin damages the cyst wall, leading to excystation.
    • Metacyst stage: The cytoplasm detaches from the cyst wall, freeing the quadrinucleate amoeba.
    • Metacystic trophozoites: The nuclei divide, forming 8 nuclei, each surrounded by cytoplasm, resulting in 8 small metacystic trophozoites.
    • Optimal habitat: Submucosal tissue of the caecum and colon.
    • Some metacystic trophozoites develop into precystic forms and cysts, which are eliminated in feces, continuing the cycle.

    Pathogenesis of Entamoeba Histolytica

    • Causes intestinal and extraintestinal amoebiasis.
    • Incubation period: Variable, ranging from 4 days to 4 months.
    • Forms and severity of amoebiasis depend on the affected organ and extent of damage.

    Intestinal Amoebiasis

    • Metacystic trophozoites invade the columnar epithelial cells of the colon.
    • Penetration facilitated by trophozoite motility and the tissue lytic enzyme, histolysin, which breaks down the mucosal epithelium.
    • Results in ulcers with pinhead centers and raised edges.
    • May heal spontaneously if invasion remains superficial.
    • More often, amoebae penetrate the submucosal layer, multiplying rapidly and causing lytic necrosis, leading to abscess formation.
    • Abscesses break down, forming ulcers.
    • Ulcers are multiple, mainly located in the caecum and the sigmoidorectal region.
    • Initially appear as raised nodules with pouting edges, later breaking down, releasing brownish necrotic material containing numerous trophozoites.
    • Typical amoebic ulcer is flask-shaped with a narrow mouth and neck, and a large, rounded base.
    • Ulcers generally don't extend beyond the submucosal layer but spread laterally in the submucosa, causing undermining and patchy mucosal loss.
    • Amoebae are found at the periphery of the lesions and extend into surrounding healthy tissues.
    • In rare instances, ulcers may affect the muscular and serous coats of the colon, causing perforation and peritonitis.
    • Deep ulcers form scars, leading to strictures, partial obstruction, and thickening of the gut wall.
      • This amoebic granuloma or amoeboma may be mistaken for a malignant tumor.

    Clinical Features of Intestinal Amoebiasis

    • Incubation period: Variable, ranging from 1 to 4 months.
    • Clinical course: Characterized by prolonged latency, relapses, and intermissions.
    • Amoebic dysentery:
      • Large, foul-smelling, brownish-black stools with blood-streaked mucus and feces.
      • Erythrocytes in stools appear clumped and reddish-brown.
      • Presence of E.histolytica trophozoites with ingested erythrocytes is a key diagnostic feature.
    • Patient is usually afebrile and non-toxic.
    • Fulminant colitis: Confluent ulceration and necrosis of the colon, accompanied by fever and toxicity.
    • Not all intestinal amoebiasis manifests as dysentery.
      • It can present as diarrhea or vague abdominal symptoms.
    • Chronic involvement of the caecum can mimic appendicitis.

    Extraintestinal Amoebiasis

    • Entamoeba histolytica can affect organs beyond the intestines.
    • Major sites of extraintestinal amoebiasis:
      • Hepatic amoebiasis (including liver abscesses)
      • Pulmonary amoebiasis
      • Metastatic amoebiasis
      • Cutaneous amoebiasis
      • Genitourinary amoebiasis

    Hepatic Amoebiasis

    • Liver enlargement and tenderness are common, without significant liver function impairment or fever.
    • Damage may not be directly caused by amoebae but by lysosomal enzymes and cytokines from inflammatory cells surrounding the trophozoites.
    • Liver abscesses occur in 5–10% of individuals with intestinal amoebiasis.
    • Liver abscesses usually solitary, located in the upper right lobe of the liver, contain thick chocolate brown pus.
    • Multiple abscesses and abscesses pressing on the biliary tract can lead to jaundice.
    • Uncontrolled abscesses can rupture into surrounding tissues, including the lung, pleural cavity, pericardium, peritoneal cavity, stomach, intestine, inferior vena cava, or externally through the abdominal wall and skin.
    • Lower incidence in women and rare in children younger than 10 years.

    Pulmonary Amoebiasis

    • Often results from a hepatobronchial fistula, characterized by expectoration of chocolate brown sputum.
    • Less commonly, amoebic empyema can develop.
    • Clinical presentation: Severe pleuritic chest pain, dyspnea (difficulty breathing), and non-productive cough.

    Treatment of Amoebiasis

    • Luminal amoebicides:
      • Diloxanide furoate, iodoquinol, paromomycin, and tetracycline act within the intestinal lumen but not in tissues.
    • Tissue amoebicides:
      • Emetine, chloroquine, etc., effective in systemic infections, but less so in the intestine.
      • Dosage of chloroquine for amoebic liver abscess: 1 g for 2 days followed by 500 mg daily for 3 weeks.
    • Both luminal and tissue amoebicides:
      • Metronidazole and related compounds (tinidazole and ornidazole) are effective in both the intestine and tissues, and are preferred for treating amoebic colitis and amoebic liver abscess.

    Prophylaxis

    • General measures:
      • Similar to other fecal-oral infections.
      • Food and water must be protected from contamination with human excreta.
    • Additional approaches:
      • Detection and treatment of carriers.
      • Exclusion of carriers from food-handling professions.
      • Health education and promotion of healthy personal hygiene habits.

    Entamoeba histolytica

    • A parasitic protozoan responsible for amoebic dysentery and amoebic liver abscess.
    • Found globally, with higher prevalence in tropical regions.
    • Estimated to infect 10% of the world's population and 50% of those in developing countries.
    • Third leading parasitic cause of death worldwide, after malaria and schistosomiasis.

    Morphology

    • Entamoeba histolytica exists in three forms:
      • Trophozoite: The vegetative or growing stage. Present in tissues. Irregular shape, 12-60 μm in size. Actively motile in dysenteric stool.
      • Precyst: Transition stage between trophozoite and cyst.
      • Cyst: The infective stage, passed in feces. Spherical, 10-20 μm in size.

    Life Cycle

    • Entamoeba histolytica has a single-host life cycle (human).
    • Infective form: Mature quadrinucleate cyst
    • Transmission: Ingestion of contaminated food and water containing cysts.
    • Excystation occurs in the ileum, releasing metacystic trophozoites.
    • Metacystic trophozoites multiply in the colon.
    • Some trophozoites transform into precystic stages and cysts, completing the cycle.

    Pathogenesis

    • Causes intestinal and extraintestinal amoebiasis.
    • Incubation period varies from 4 days to 4 months.
    • Intestinal amoebiasis:
      • Metacystic trophozoites penetrate the colonic epithelium, causing ulcers.
      • Amoeba utilize histolysin to penetrate the mucosal barrier.
      • Ulcers may be superficial or deep.
      • Deep ulcers may lead to scarring, strictures, and amoebomas.

    Clinical Features

    • Intestinal amoebiasis presents as:
      • Amoebic dysentery: Characterized by bloody, foul-smelling stools.
      • Diarrhea: Often asymptomatic or with vague abdominal complaints.
      • Chronic caecal involvement: Mimicking appendicitis.

    Extraintestinal Amoebiasis

    • Hepatic Amoebiasis:
      • Liver abscesses: Usually solitary, located in the right lobe.
      • Characterized by chocolate-brown pus (anchovy sauce pus).
      • May lead to complications such as rupture into surrounding organs.
    • Pulmonary Amoebiasis:
      • Often secondary to liver abscesses.
      • Results in hepatobronchial fistula with expectoration of chocolate brown sputum.
    • Other forms:
      • Metastatic amoebiasis: Affecting various organs.
      • Cutaneous amoebiasis: Skin infections.
      • Genitourinary amoebiasis: Affecting reproductive organs.

    Treatment

    • Luminal amoebicides: Act in the intestinal lumen (Diloxanide furoate, iodoquinol, paromomycin, Tetracycline)
    • Tissue amoebicides: Act systemically (Emetine, chloroquine)
    • Both luminal and tissue amoebicides: Preferred treatment (Metronidazole, tinidazole, ornidazole)

    Prophylaxis

    • General measures for fecal-oral infections.
    • Food and water protection from contamination with human excreta.
    • Detection and treatment of carriers, exclusion from food handling.
    • Health education and promotion of healthy personal habits.

    Entamoeba histolytica

    • Entamoeba histolytica causes amoebic dysentery and amoebic liver abscess
    • It is a common parasite, particularly in tropical regions
    • It is the third leading parasitic cause of death worldwide

    Morphology

    • Entamoeba histolytica exists in three forms: trophozoite, precystic, and cyst
    • The trophozoite is the active, feeding stage, found in tissues
    • It is irregular in shape, ranging from 12-60 µm in size
    • The trophozoite displays amoeboid movement with finger-like projections
    • It contains a single nucleus with a central karyosome
    • Trophozoites from acute dysenteric stools often contain phagocytosed red blood cells, a distinguishing feature
    • The trophozoite divides by binary fission
    • The precystic stage is a transition form, losing food vacuoles and becoming rounder
    • It contains a glycogen vacuole and two chromatid bars
    • The cyst is the infective stage, spherical and 10-20 µm in size
    • Mature cysts contain four nuclei (quadrinucleate)
    • Cysts are resistant to environmental conditions and can survive for extended periods

    Life Cycle

    • The life cycle of Entamoeba histolytica occurs solely in humans
    • Infection occurs through ingestion of mature cysts
    • Cysts reach the small intestine unharmed and undergo excystation
    • The metacyst stage releases quadrinucleate amoebae which then divide to form 8 metacystic trophozoites
    • Optimal habitat for metacystic trophozoites is the submucosal tissue of the caecum and colon

    Pathogenesis

    • E. histolytica causes both intestinal and extraintestinal amoebiasis
    • Incubation period ranges from 4 days to 4 months
    • The severity and manifestation of amoebiasis depend on the affected organ and extent of damage

    Intestinal Amoebiasis

    • Metacystic trophozoites penetrate the colon's epithelium
    • Penetration is facilitated by the amoebae's motility and histolysin, a tissue lytic enzyme
    • Amoebic penetration creates discrete ulcers with a central pinhead and raised edges
    • Deeper penetration leads to submucosal abscess formation
    • Amoebic ulcers are flask-shaped, forming scar tissue that may lead to strictures and thickening of the gut wall

    Clinical Features

    • Intestinal amoebiasis presents with diverse symptoms, from mild diarrhea to severe dysentery
    • Patients with amoebic dysentery experience bloody, foul-smelling stools and can exhibit fever and toxicity in more severe cases
    • In chronic cases, involvement of the caecum can mimic appendicitis

    Extraintestinal Amoebiasis

    • Liver abscess is the most common extraintestinal manifestation
    • Other forms include pulmonary, metastatic, cutaneous, and genitourinary amoebiasis

    Hepatic Amoebiasis

    • Liver abscesses are often solitary and located in the upper right lobe
    • Jaundice occurs with multiple abscesses or blockage of the biliary tract
    • Untreated abscesses can rupture into surrounding tissues, including the lung, pleura, pericardium, and peritoneum

    Pulmonary Amoebiasis

    • Often arises from a hepatobronchial fistula, resulting in brown sputum
    • Symptoms include pleuritic chest pain, dyspnea, and non-productive cough

    Treatment

    • Luminal amoebicides (diloxanide furoate, iodoquinol, paromomycin, and tetracycline) act in the intestinal lumen but not tissues
    • Tissue amoebicides (emetine, chloroquine) target systemic infection and are less effective in the intestine
    • Metronidazole and related compounds (tinidazole, ornidazole) are the drugs of choice for both intestinal and systemic amoebiasis

    Prophylaxis

    • Prevention measures focus on avoiding fecal-oral contamination of food and water
    • Detection and treatment of carriers are essential
    • Promoting healthy personal habits and sanitation practices is vital for control

    Entamoeba Histolytica

    • A parasitic protozoan that causes amoebic dysentery and amoebic liver abscess.
    • Globally prevalent, with higher rates in tropical regions.
    • Estimated to infect 10% of the world population and 50% of those in developing countries.
    • Third leading parasitic cause of death, after malaria and schistosomiasis.

    Morphology

    • Exists in three forms: trophozoite, precyst, and cyst.
    • Trophozoite:
      • Active, growing stage.
      • Found in tissues, irregularly shaped, 12-60 μm in size (average 20 μm).
      • Larger and more active in dysenteric stool, smaller in convalescent and carrier stages.
      • Cytoplasm: clear outer ectoplasm and finely granular inner endoplasm.
      • Possesses finger-like pseudopodia for movement.
      • Contains a spherical nucleus (4-6 μm) with a central karyosome.
      • Often contain phagocytosed red blood cells, a diagnostic feature.
      • Divides via binary fission every 8 hours.
      • Survives for up to 5 hours at 37°C, but is killed by drying, heat, and chemical sterilization.
    • Precystic Stage:
      • Formed when trophozoites undergo encystment in the intestinal lumen.
      • Round or oval shape with a large glycogen vacuole and two chromatid bars.
      • Secretes a cyst wall around itself.
    • Cystic Stage:
      • Spherical, 10-20 μm in diameter.
      • Early cyst has one nucleus and two chromatid bars.
      • Mature cyst has four nuclei.
      • Nuclear chromatin and chromatoid bodies stain dark blue or black with hematoxylin.
      • With iodine stain, nuclear chromatin and karyosome appear bright yellow, while chromatoid bodies remain clear.

    Life Cycle

    • Only occurs in humans.
    • Infective form: Mature quadrinucleate cyst.
    • Mode of transmission: Ingestion of cysts through contaminated food and water.
    • Excystation: Cyst wall breaks down in the ileum by trypsin, releasing the amoeba.
    • Metacystic stage: The amoeba (now quadrinucleate) detaches from the cyst wall.
    • Metacystic trophozoites: The amoeba undergoes division to form 8 nuclei, each surrounded by cytoplasm, resulting in smaller metacystic trophozoites.
    • Ideal habitat: Submucosal tissue of the caecum and colon.
    • Some trophozoites develop into precystic forms and cysts, which are excreted in feces, completing the cycle.

    Pathogenesis

    • Causes intestinal and extraintestinal amoebiasis.
    • Incubation period: Highly variable, typically 4 days to 4 months.
    • Amoebiasis severity depends on the affected organ and extent of damage.

    Intestinal Amoebiasis

    • Metacystic trophozoites penetrate the colon's epithelial cells, facilitated by their motility and the enzyme histolysin.
    • Penetration creates small ulcers with raised edges.
    • Some invasions are superficial and heal spontaneously.
    • Deeper penetration results in submucosal abscesses due to amoeba multiplication and tissue lysis.
    • Abscess rupture leads to ulcers, which are often multiple and primarily localized in the caecum and sigmoidorectal region.
    • Amoebic ulcers appear as raised nodules with pouting edges and later discharge necrotic material with trophozoites.
    • Typically flask-shaped in cross-section, with a narrow mouth and a wide, rounded base.
    • Amoebae spread laterally in the submucosa, causing undermining and mucosal loss.
    • Ulceration may involve the muscular and serous coats, leading to perforation, peritonitis, and scarring.
    • Scarring can result in strictures, obstruction, and thickening of the gut wall.
    • Amoebic granulomas (amoebomas) may mimic malignant tumors.

    Clinical Features

    • Incubation period: 1-4 months.
    • Symptoms:
      • Prolonged latency, relapses, and intermissions.
      • Amoebic dysentery: characterized by large, foul-smelling stools with bloodstreaked mucus.
      • Erythrocytes in stools are clumped and reddish-brown.
      • Fever and toxicity are usually absent.
      • Fulminant colitis: Extensive ulceration and necrosis of the colon are present.
      • Diarrhea or vague abdominal discomfort (uncomfortable belly or growling abdomen).
      • Chronic caecal involvement mimicking appendicitis.

    Extraintestinal Amoebiasis

    • Occurs when the amoeba spreads beyond the intestines.
    • Common forms:
      • Hepatic amoebiasis (liver abscess)
      • Pulmonary amoebiasis
      • Metastatic amoebiasis
      • Cutaneous amoebiasis
      • Genitourinary amoebiasis

    Hepatic Amoebiasis

    • Enlarged, tender liver without significant liver dysfunction or fever.
    • Liver damage may be caused indirectly by enzymes and cytokines from inflammatory cells surrounding the amoeba.
    • Amoebic liver abscesses develop in 5-10% of cases.
    • Abscesses contain thick, chocolate-brown pus (anchovy sauce pus) composed of liquefied necrotic liver tissue.
    • Usually solitary and located in the upper right lobe of the liver.
    • Multiple abscesses can cause jaundice by pressing on the biliary tract.
    • Untreated abscesses can rupture into adjacent tissues, such as the lung, pleural cavity, pericardium, peritoneal cavity, stomach, intestine, inferior vena cava, or externally through the abdomen and skin.
    • Less common in women and rare in children under 10 years old.

    Pulmonary Amoebiasis

    • Results from a hepatobronchial fistula, leading to expectoration of chocolate-brown sputum.
    • Less commonly, amoebic empyema develops.
    • Symptoms: Severe pleuritic chest pain, dyspnea, and non-productive cough.

    Treatment

    • Luminal amoebicides:
      • Target amoebae in the intestinal lumen.
      • Include diloxanide furoate, iodoquinol, paromomycin, and tetracycline.
    • Tissue amoebicides:
      • Effective for systemic infections but less effective in the intestine.
      • Examples include emetine and chloroquine.
      • Chloroquine dosage for amoebic liver abscess: 1 g for 2 days followed by 5 g daily for 3 weeks.
    • Both luminal and tissue amoebicides:
      • Preferred for treating amoebic colitis and liver abscess.
      • Examples include metronidazole, tinidazole, and ornidazole.

    Prophylaxis

    • Similar to other fecal-oral infections.
    • Prevention includes protecting food and water from contamination with human excreta.
    • Detecting and treating carriers and excluding them from food handling helps control spread.
    • Promoting healthy personal habits and education are essential.

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    Description

    This quiz covers the essential aspects of Entamoeba histolytica, a protozoan parasite responsible for amoebic dysentery. Explore its morphology, lifecycle stages, and global impact on human health. Understanding this parasite is crucial for studying infectious diseases.

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