I obtained sources for this review by searching PubMed until Aug 31, 2002, with the keywords: Entamoeba histolytica, amebiasis, amoebiasis, amebic liver abscess, amoebic liver abscess, amebic colitis, amoebic colitis, amebic dysentery, and amoebic dysentery. The search was restricted to papers in the English language.
SeminarAmoebiasis
Section snippets
The organism
Unlike many protozoan parasites, E histolytica has a simple lifecycle, existing as either the infectious cyst form or the amoeboid trophozoite stage. Human beings, and perhaps some non-human primates, are the only natural hosts. Infection usually begins with the ingestion of the cysts in food or water that has been contaminated by human faeces. E histolytica cysts are round, usually 10–15 μm in diameter, and are surrounded by a refractile wall that may include chitin. They contain four nuclei,
Epidemiology—E histolytica, the doppelganger
E histolytica is distributed throughout the world, and is a substantial health risk in almost all countries where the barriers between human faeces and food and water are inadequate. Remarkably, our understanding of the worldwide and regional prevalence of E histolytica infection is now changing, thanks to the discovery that the organism called E histolytica on the basis of its morphology is, in fact, two genetically distinct species. Brumpt8 suggested in 1925 that the genus Entamoeba included
Pathophysiology
The pathological range of amoebic colitis encompasses mucosal thickening, multiple discrete ulcers separated by regions of colonic mucosa of normal appearance, diffusely inflamed and oedematous mucosa, and necrosis and perforation of the intestinal wall (figure 2). The gross findings can strongly resemble those seen in inflammatory bowel disease.48 Disease begins when E histolytica trophozoites adhere to colonic epithelial cells, probably through the galactose/N-acetylgalactosamine specific
Gastrointestinal
Many individuals with E histolytica infection have no symptoms, and can clear their infection without any signs of disease. However, 4–10% of asymptomatic individuals infected with E histolytica develop disease over a year.19, 90 Patients with amoebic colitis present with bloody diarrhoea and abdominal pain and tenderness.91, 92 The onset is often gradual, with patients reporting several weeks of symptoms. Multiple small volume mucoid stools are common, but profuse, watery diarrhoea might be
Diagnosis
The diagnosis of amoebic colitis rests on the demonstration of E histolytica in the stool or colonic mucosa of patients with diarrhoea. For years this diagnosis was done by microscopic examination of stool, a technique that probably identified most cases of amoebic colitis when used by skilled individuals (differentiation of E histolytica trophozoites from leucocytes and other intestinal protozoa can be difficult), and with the examination of at least three properly prepared stool samples.119,
Amoebiasis
In an age where drug resistance has become the rule, rather than the exception, for many microbial pathogens, I find it refreshing to report that the cornerstone of treatment for amoebiasis remains the nitroimidazole derivatives (metronidazole, tinidazole, ornidazole). Because metronidazole is the only nitroimidazole available in the USA, my recommendations (table 3) focus on this agent, but the other tinidazole agents are equally or slightly more effective. Amoebic colitis is treated by
The future
Walker and Sellards141 discovered that two different individuals infected with the same stool sample from a patient with amoebic dysentery could show completely different clinical manifestations (asymptomatic cyst passer or amoebic colitis). Since then, investigators have questioned why some hosts seem to be more susceptible to disease, and whether E histolytica isolates might differ in their virulence. We now have the techniques to try and answer both of those queries. Studies in the mouse
Search strategy
References (144)
- et al.
Entamoeba histolytica has an alcohol dehydrogenase homologous to the multifunctional adhE gene product of Escherichia coli
Mol Biochem Parasitol
(1994) - et al.
The differentiation of invasive and non-invasive Entamoeba histolytica by isoenzyme electrophoresis
Trans R Soc Trop Med Hyg
(1978) - et al.
Ribosomal RNA genes of ‘pathogenic’ and ‘nonpathogenic’ Entamoeba histolytica are distinct
Mol Biochem Parasitol
(1991) - et al.
Entamoeba histolytica infection and AIDS
Am J Med
(1991) - et al.
Microscopy, PCR and ELISA applied to the epidemiology of amoebiasis in Greece
Parasitol Int
(2001) - et al.
Gender distribution in asymptomatic and invasive amebiasis
Am J Gastroenterol
(2000) The epidemiology of amoebiasis
Adv Parasitol
(1968)- et al.
Transmission of Entamoeba histolytica within a family complex
Trans R Soc Trop Med Hyg
(1995) Structure and function of the Entamoeba histolytica Gal/GalNAc lectin
Int Rev Cytol
(2002)Amoebapores
Parasitol Today
(1997)
Entamoeba histolytica: target cells killed by trophozoites undergo DNA fragmentation which is not blocked by Bcl-2
Exp Parasitol
Extracellular matrix-induced signaling in Entamoeba histolytica: its role in invasiveness
Parasitol Today
Epithelial cell-initiated inflammation plays a crucial role in early tissue damage in amebic infection of human intestine
Gastroenterology
Isolation and partial characterization of a surface glycoconjugate of Entamoeba histolytica
Mol Biochem Parasitol
Identification and partial characterization of a lipophosphoglycan from a pathogenic strain of Entamoeba histolytica
Mol Biochem Parasitol
The major surface antigens of Entamoeba histolytica trophozoites are GPI-anchored proteophosphoglycans
J Mol Biol
Amoebic colitis: review of 295 cases
Trans R Soc Trop Med Hyg
Necrotizing amebic colitis: a frequently fatal complication
Am J Surg
The aphorisms of Hippocrates
Massenhafte Entwickelung von Amöben im Dickdarm
Arch F Path Anat
Metabolism of Entamoeba histolytica Schaudinn, 1903
Adv Parasitol
Direct evidence for secondary loss of mitochondria in Entamoeba histolytica
Proc Natl Acad Sci USA
Evidence for the bacterial origin of genes encoding fermentation enzymes of the amitochondriate protozoan parasite Entamoeba histolytica
J Bacteriol
A role for a galactose lectin and its ligands during encystment of Entamoeba
J Eukaryot Microbiol
Étude sommaire de l' ≪Entamoeba dispar≫ n sp Amibe a kystes quadrinucléés, parasite de l'homme
Bull Acad Méd (Paris)
Genomic differences between pathogenic and nonpathogenic Entamoeba histolytica
Proc Natl Acad Sci USA
Isolation of a strain-specific Entamoeba histolytica cDNA clone
J Clin Microbiol
Entamoeba histolytica as a commensal intestinal parasite in homosexual men
N Engl J Med
Prevalence and immune response to Entamoeba histolytica infection in preschool children in Bangladesh
Am J Trop Med Hyg
Entamoeba histolytica and Entamoeba dispar infection in children in Bangladesh
J Infect Dis
Seropositivity for and intestinal colonization with Entamoeba histolytica and Entamoeba dispar in individuals in northeastern Brazil
J Clin Microbiol
Field study on the distribution of Entamoeba histolytica and Entamoeba dispar in the northern Philippines as detected by the polymerase chain reaction
Am J Trop Med Hyg
A longitudinal study of asymptomatic carriers of pathogenic zymodemes of Entamoeba histolytica
S Afr Med J
Comparison of antigen-capture ELISA to stool-culture methods for the detection of asymptomatic Entamoeba species infection in Kafer Daoud, Egypt
Am J Trop Med Hyg
Diagnosis of amoebic colitis by antigen capture ELISA in patients presenting with acute diarrhoea in Cairo, Egypt
Trop Med Int Health
Prevalence of Entamoeba histolytica infection
Mexico
Seroepidemiology of amebiasis in Mexico
Am J Trop Med Hyg
Amebic abscess of the liver: ultrasound guided puncture
Ann Chir
Summary of notifiable diseases, United States
MMWR Morb Mortal Wkly Rep
Evaluation of an antigen-capture enzyme immunoassay for detection of Entamoeba histolytica in stool samples
Eur J Clin Microbiol Infect Dis
Prevalence and clinical importance of Entamoeba histolytica in two high-risk groups: travelers returning from the tropics and male homosexuals
J Infect Dis
Amebic liver abscess: a therapeutic approach
Rev Infect Dis
Amebic liver abscess
Arch Surg
Hepatic amebiasis among patients in a public teaching hospital
South Med J
A comparison of amebic and pyogenic abscess of the liver
Medicine (Baltimore)
Hepatic amebiasis: A twenty year experience and analysis of 263 cases
Surg Gync Obstet (Int Abstr Surg)
New concepts of amebic liver abscess derived from hepatic imaging, serodiagnosis, and hepatic enzymes in 67 consecutive cases in San Diego
Medicine (Baltimore)
Increased frequency of HLA-DR3 and complotype SCO1 in Mexican mestizo children with amoebic abscess of the liver
Parasite Immunol
HLA characterization in adult asymptomatic cyst passers of Entamoeba histolytica/E dispar
Parasitol Res
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Multi-locus sequence analysis reveals phylogenetically segregated Entamoeba histolytica population.
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