Amebiasis, or amoebic dysentery Dysentery Acute inflammation of the intestine associated with infectious diarrhea of various etiologies, generally acquired by eating contaminated food containing toxins, biological derived from bacteria or other microorganisms. Dysentery is characterized initially by watery feces then by bloody mucoid stools. It is often associated with abdominal pain; fever; and dehydration. Gastroenteritis, is an infection caused by the parasite Entamoeba Entamoeba A genus of ameboid protozoa characterized by the presence of beaded chromatin on the inner surface of the nuclear membrane. Its organisms are parasitic in invertebrates and vertebrates, including humans. Nitroimidazoles histolytica. Transmission is through the fecal-oral route Fecal-oral route Echovirus or by consumption of contaminated food and water. Most patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship infected with E. histolytica are asymptomatic, but about 10% may develop dysentery Dysentery Acute inflammation of the intestine associated with infectious diarrhea of various etiologies, generally acquired by eating contaminated food containing toxins, biological derived from bacteria or other microorganisms. Dysentery is characterized initially by watery feces then by bloody mucoid stools. It is often associated with abdominal pain; fever; and dehydration. Gastroenteritis. Invasive infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease are characterized by abdominal pain Abdominal Pain Acute Abdomen, fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, and bloody diarrhea Bloody diarrhea Diarrhea, and can lead to serious complications including liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy abscesses, intestinal fistulas, or fulminant colitis Colitis Inflammation of the colon section of the large intestine, usually with symptoms such as diarrhea (often with blood and mucus), abdominal pain, and fever. Pseudomembranous Colitis. Diagnosis is usually made based on stool studies or the detection of immunologic markers. Treatment consists of both an absorbable amebicidal agent such as metronidazole Metronidazole A nitroimidazole used to treat amebiasis; vaginitis; trichomonas infections; giardiasis; anaerobic bacteria; and treponemal infections. Pyogenic Liver Abscess and an intraluminal amebicidal agent such as paromomycin Paromomycin An aminoglycoside antibacterial and antiprotozoal agent produced by species of streptomyces. Amebicides.
Last updated: 10 Mar, 2022
Causative organism: anaerobic protozoan parasites of the Entamoeba Entamoeba A genus of ameboid protozoa characterized by the presence of beaded chromatin on the inner surface of the nuclear membrane. Its organisms are parasitic in invertebrates and vertebrates, including humans. Nitroimidazoles genus
Transmission occurs through the ingestion of cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change:
Risk factors and high-risk populations:
Entamoeba Entamoeba A genus of ameboid protozoa characterized by the presence of beaded chromatin on the inner surface of the nuclear membrane. Its organisms are parasitic in invertebrates and vertebrates, including humans. Nitroimidazoles histolytica photomicrograph, cyst stage
Image: “ Entamoeba Entamoeba A genus of ameboid protozoa characterized by the presence of beaded chromatin on the inner surface of the nuclear membrane. Its organisms are parasitic in invertebrates and vertebrates, including humans. Nitroimidazoles histolytica cyst” by Yasser. License: CC BY 2.0
Trophozoites
Trophozoites
Cells or feeding stage in the life cycle of sporozoan protozoa. In the malarial parasite, the trophozoite develops from the merozoite and then splits into the schizont. Trophozoites that are left over from cell division can go on to form gametocytes.
Amebicides of
Entamoeba
Entamoeba
A genus of ameboid protozoa characterized by the presence of beaded chromatin on the inner surface of the nuclear membrane. Its organisms are parasitic in invertebrates and vertebrates, including humans.
Nitroimidazoles histolytica with ingested
erythrocytes
Erythrocytes
Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production.
Erythrocytes: Histology stained with trichrome:
Ingested
erythrocytes
Erythrocytes
Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production.
Erythrocytes: Histology appear as dark inclusions. The parasites contain nuclei that have the typical small, centrally located karyosome and thin, uniform peripheral
chromatin
Chromatin
The material of chromosomes. It is a complex of dna; histones; and nonhistone proteins found within the nucleus of a cell.
DNA Types and Structure. Erythrophagocytosis, or ingestion of
RBCs
RBCs
Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production.
Erythrocytes: Histology, is the distinguishing feature between E. histolytica and E. dispar.
The life cycle Cycle The type of signal that ends the inspiratory phase delivered by the ventilator Invasive Mechanical Ventilation of Entamoeba Entamoeba A genus of ameboid protozoa characterized by the presence of beaded chromatin on the inner surface of the nuclear membrane. Its organisms are parasitic in invertebrates and vertebrates, including humans. Nitroimidazoles spp. is dependent on the infection of a host because transition through the life stages occurs within the host’s intestinal tract.
Cyst stage:
Trophozoite stage:
The pathogenesis of invasive
Entamoeba
Entamoeba
A genus of ameboid protozoa characterized by the presence of beaded chromatin on the inner surface of the nuclear membrane. Its organisms are parasitic in invertebrates and vertebrates, including humans.
Nitroimidazoles histolytica infection:
In 10% of cases, E. histolytica colonizes the
large intestine
Large intestine
The large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal.
Colon, Cecum, and Appendix: Anatomy mucosa and invades via
secretion
Secretion
Coagulation Studies of proteinases and lytic
enzymes
Enzymes
Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body’s constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules.
Basics of Enzymes. This causes cellular
necrosis
Necrosis
The death of cells in an organ or tissue due to disease, injury or failure of the blood supply.
Ischemic Cell Damage and lysis of the membranes, respectively. This chain of events induces mucosal cell
apoptosis
Apoptosis
A regulated cell death mechanism characterized by distinctive morphologic changes in the nucleus and cytoplasm, including the endonucleolytic cleavage of genomic DNA, at regularly spaced, internucleosomal sites, I.e., DNA fragmentation. It is genetically-programmed and serves as a balance to mitosis in regulating the size of animal tissues and in mediating pathologic processes associated with tumor growth.
Ischemic Cell Damage and disrupts
tight junctions
Tight junctions
Cell-cell junctions that seal adjacent epithelial cells together, preventing the passage of most dissolved molecules from one side of the epithelial sheet to the other.
The Cell: Cell Junctions between cells, allowing for flask-shaped ulcers, abscesses, and fistulas to form. Invasion may reach the portal venous system, through which E. histolytica can spread to other organs.
The incubation Incubation The amount time between exposure to an infectious agent and becoming symptomatic. Rabies Virus period is usually 2–4 weeks once ingested, but symptoms may develop up to 1 year after infection.
90% of all Entamoeba Entamoeba A genus of ameboid protozoa characterized by the presence of beaded chromatin on the inner surface of the nuclear membrane. Its organisms are parasitic in invertebrates and vertebrates, including humans. Nitroimidazoles infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease are asymptomatic:
“Anchovy paste” aspirate from the liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy abscess Abscess Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection. Chronic Granulomatous Disease of a patient with invasive E. histolytica infection
Image: “Aspirate of “anchovy paste”” by Palak Patel et al AL Amyloidosis. License: CC BY 4.0Amoebic
abscess
Abscess
Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection.
Chronic Granulomatous Disease in the left lobe of the
liver
Liver
The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood.
Liver: Anatomy:
Coronal
Coronal
Computed Tomography (CT) T2-weighted
magnetic resonance cholangiopancreatography
Magnetic resonance cholangiopancreatography
Non-invasive diagnostic technique for visualizing the pancreatic ducts and bile ducts without the use of injected contrast media or x-ray. Mri scans provide excellent sensitivity for duct dilatation, biliary stricture, and intraductal abnormalities.
Primary Sclerosing Cholangitis (MRC) showing a collection of heterogeneous material in the left lobe of the
liver
Liver
The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood.
Liver: Anatomy
The diagnosis of amebiasis is based on clinical suspicion as well as confirmatory testing. Several testing modalities may be used.
All E. histolytica infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease should be treated regardless of the absence or severity of symptoms; however, E. dispar infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease do not need to be treated.
All conditions that cause nonspecific or bloody diarrhea Bloody diarrhea Diarrhea are differential diagnoses for amebiasis.