Entamoeba histolytica introduction there is a large number of species of amoebae which parasitise the human intestinal tract. The cyst wall of entamoeba invadens ei, a model for the human pathogen entamoeba histolytica, is composed of fibrils of chitin and three chitinbinding lectins called jacob, jessie3, and chitinase. Entamoeba invadens is a species that can cause a disease similar to e. Entamoeba histolytica is an anaerobic parasitic protozoan that infects the digestive tract of predominantly humans and other primates.
Pathogenesis of infection by entamoeba histolytica springerlink. Giardiasis is the most frequently diagnosed intestinal parasitic disease in the united states and among travelers with chronic diarrhea. Entamoeba histolytica causes about 50 million infections worldwide with a death rate of over 100,000 annually. Entamoeba histolytica and entamoeba dispar basic guidelines a. Itis taxonomy is based on the latest scientific consensus available, and is provided as a general reference source for interested parties. Detection of the endosomal sorting complex required for. The other species are important because they may be confused with e.
Our understanding of its epidemiology has dramatically changed since this amoeba was distinguished from another morphologically similar one, entamoeba dispar, a non. Differential detection of entamoeba histolytica, entamoeba dispar, and entamoeba. Entamoeba histolytica trophozoites and lipopeptidophosphoglycan. Entamoeba histolytica a number of outbreaks have resulted from a breakdown in sanitation or behavioral practices of people. Structure of the nuclei of amoebas in the family entamoebidae. In endemic developing countries where resources are limited, microscopic examinations based on wheatley trichrome staining is commonly used for diagnosis of intestinal amoebiasis. A higher prevalence in tropical and subtropical countries 10 % of the world population.
Morphology of entamoeba protozoa microorganisms zoology. Predominantly infecting humans and other primates causing amoebiasis, e. Further inspection of that zone revealed a network of. Hostparasite interactions in entamoeba histolytica and entamoeba dispar. Like morphology, this too demonstrates the elusiveness of clear. Although many people harbour this organism world wide, only about 10% develop clinically. Entamoeba histolytica is the cause of high levels of morbidity and mortality throughout the developing world, having been ranked as the third most important parasitic agent of disease after malaria and schistosomiasis. Entamoeba histolytica is the responsible parasite of amoebiasis and remains one of the top. Entamoeba histolytica is a an anaerobic parasitic protozoan that is responsible for the development of amoebiasis. The human intestinal protozoan parasite entamoeba histolytica produces a number of virulence factors such as a galspecific adhesin, cysteine proteinases and a family of small 77 a.
The outer ectoplasm is clear, transparent and refractile. The majority of infections are asymptomatic and apparently nonpathogenic. Jan 23, 2016 morphology entamoeba histolytica occurs in 3 forms trophozoite precyst cyst 4. Intestinal amoebiasis caused by entamoeba histolytica occurs throughout the world and. In 1981, it was estimated that up to 500 million people are infected annually 265. Entamoeba histolytica is an invasive intestinal amoeba morphologically indistinguishable from. Cytoplasm of trophozoite is divided into clear ectoplasm. Start studying microbiology parasites entamoeba histolytica, acanthamoeba, naegleria free living amoebae.
Some interesting features include evidence for lateral gene transfer from bacteria and large numbers of vesicle trafficking genes, transmembrane. The genome is predicted to be 24 mb with 14 chromosomes and is functionally tetraploid. Others such as entamoeba coli not to be confused with escherichia coli and entamoeba dispar are harmless. The tree shown is the one inferred using the neighborjoining. In its life cycle, it passes through three distinct morphological stages or forms. Pdf pentamoeba histolytica is a cosmopolitan, parasitic. The pathogenic or invasive species has retained the name e. While the parasitic amoebozoan entamoeba histolytica has been wellstudied for its role in human. Entamoeba coli introduction entamoeba coli is a nonpathogenic amoeba with world wide distribution. Some important species of entamoeba are described below. In vitro induction of entamoeba histolytica cystlike structures from. It is the cause of amebic dysentery bloody diarrhea as well as colonic ulcerations. Learn vocabulary, terms, and more with flashcards, games, and other study tools.
While every effort has been made to provide the most reliable and uptodate information available, ultimate legal requirements with respect to species are contained in. The tree shown is the one inferred using the neighbor joining. Entamoeba histolytica was first reported by losch 1875 in russia, but he described it as amoeba coli. The structure and life cycle of entamoeba with diagram. Fecal oral spread amoeba invade colonic crypts, burrow into lamina propria, create flask shaped ulcer with broad base 40% invade portal vessels, embolize to. It inhabits the mucous and submucous layers of the large intestine.
The trophozoites are 2030 m in diameter and contain a vesicular nucleus with a central endosome, peripheral chromatin and radial achromatic fibrils imparting a cartwheel appearance. It is a parasite that infects an estimated 50 million people around the world and is a significant cause of morbidity and mortality in developing countries. Worldwide, approximately 50 million people develop colitis or extraintestinal disease, with over 100,000 deaths annually 3. Tolllike receptor signaling activation by entamoeba histolytica induces beta defensin 2 in human colonic epithelial cells. Identification of entamoeba histolytica trophozoites in. Here, we showed the presence and expression of homologous escrt genes in entamoeba histolytica. Entamoeba histolytica is a pseudopodforming nonflagellate protozoan parasite.
Entamoeba histolytica is a microscopic, naked, parasitic amoeba. Molecular differentiation of entamoeba histolytica entamoeba. Entamoeba histolytica causes amoebic dysentery in man and primates. In 1984, at least 40,000 deaths were attributed to amoebiasis. Of these entamoeba histolytica is the only species found to be associated with intestinal disease. Entamoeba histolytica distribution parasite has worldwide distribution but is most common in the tropical and subtropical areas of the world. The genus entamoeba was established by leidy in 1879. Entamoeba histolytica is an anaerobic parasitic amoebozoan, part of the genus entamoeba. Entamoeba histolytica is an invasive, pathogenic protozoan, causing amoebiasis, and an important cause of diarrhea in developing countries. In a small percentage of infections, the trophozoites become invasive and. Its possible role as an element of the innate immune response jorgetonatiuh ayalasumuano, victor m. Infection ranges from mostly asymptomatic colonization of the large bowel to invasive and potentially fatal intestinal and extraintestinal disease, with a special predilection for liver abscess formation. Entamoeba hartmanni is a nonpathogenic amoeba with world wide distribution.
View entamoeba histolytica research papers on academia. Introduction the protozoan parasite, entamoeba histolytica, is the causative agent of amoebiasis in humans. Worldwide, approximately 50 million people develop colitis or extraintestinal disease, with. The concerted action of these virulence factors causes intestinal inflamation, kills the mucosal cells. Intestinal amebiasis is caused by the protozoan entamoeba histolytica. Life cycle of entamoeba histolytica infective cysts are ingested excystation occurs in small intestine, releasing 4 amoebae which divide into 8 amoebae pass to large intestine and divide into trophozoites form cysts that pass with feces. Several protozoan species in the genus entamoeba colonize humans, but not all of them are associated with disease. Identification of the parasite is possible because of characteristic morphology of. Differential detection of entamoeba histolytica, entamoeba dispar. Entamoeba histolytica, a protozoan parasite, is the etiologic agent of amoebiasis in humans. Although the majority of individuals infected with e. We cloned and expressed the ehvps4 gene, an escrt member, to obtain the recombinant ehvps4 and generate specific antibodies, which immunodetected ehvps4 in. In a small percentage of infections, the trophozoites become. Combining serological testing with pcr or antigen detection is currently the best diagnostic approach 2.
Entamoeba histolytica is a parasite and lives in the mucous and submucous layers of the large intestine of man. Entamoeba histolytica is the pathogen responsible for invasive amoebiasis which includes amoebic dysentery and amoebic liver abscesses. It is responsible for amoebic dysentery bloody diarrhea and invasive extraintestinal amebiasis such as liver abscess, peritonitis, pleuropulmonary abscess. In most infected individuals the trophozoites exist as commensals. Pdf amoebiasis is a disease caused by the cosmopolite parasitic protozoa e.
A detergentresistant structure was found showing an apparent hole in the surface. A higher prevalence in tropical and subtropical countries 10 % of the world population carries the parasite. Entamoeba coli life cycle and location identical to. Entamoeba histolytica is microscopic and lives as an endoparasite in the upper part of the large intestine, i. Microbiology parasites entamoeba histolytica, acanthamoeba. This study identifies the first rhomboid protease in e. Morphology, life cycle, pathogenesis, clinical manifestation, lab diagnosis and treatment entamoeba histolytica is a common protozoan parasite found in the large intestine of human. It exists in two formsthe trophozoite which is the active, dividing form, and the cyst which is dormant and can survive for prolonged periods outside the host. Creation scientists suggest, as a result of the curse, e. The lifecycle of entamoeba histolytica in human host is unknown. These may merge and cause denudation of overlying mucosa, producing a minute hole of communication. Read this article to learn about the structure and life cycle of entamoeba. Pdf entamoeba histolytica pathogenic protozoan of the large.
Eukaryotic endocytosis involves multivesicular bodies formation, which is driven by endosomal sorting complexes required for transport escrt. Although a large number of people throughout the world are infected with this organism, only a small. Tonkal 3 entamoeba histolytica epidemiology a worldwide distribution. Analysis of the genome allows new insight into the. In view of the above, isoenzyme analysis, used already for 20 years sargeaunt et al. An entamoeba histolytica rhomboid protease with atypical specificity cleaves a surface lectin involved in phagocytosis and immune evasion. Entamoeba coli are a nonpathogenic ameba with world wide distribution. Phylogeny and diversity of entamoeba in cockroaches, with. Previously, it was thought that 10% of the world population was infected, but these. Multiple stool samples at least 3 should be tested before a negative result is reported. It occurs usually in the large intestine and causes internal inflammation as its name suggests histo tissue, lytic destroying. Entamoeba histolytica an overview sciencedirect topics. It is the active, motile, growing and feeding form which is pathogenic to. Entamoeba histolytica is an enteric protozoan parasite with worldwide distribution.
New insights into entamoeba histolytica pathogenesis. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. Possible function of entamoeba histolytica in creation model. The parasite is responsible for amoebiasis and liver absceses. The genus entamoeba phylum sarcodina, order amoebida, family endamoebidae is one of the many amoebae that inhabit the human gastrointestinal tract, including dientamoeba fragilis, entamoeba histolytica, entamoeba coli, entamoeba dispar, entamoeba gingivalis, entamoeba hartmanni, entamoeba moshkovskii, entamoeba polecki, chilomastix mesnili, endolimax nana, and iodamoeba butschlii. Entamoeba coli is a nonpathogenic species of entamoeba that frequently exists as a commensal parasite in the human gastrointestinal tract. To maximize recovery of cysts, stool samples in formalin, or other fixatives, should be concentrated prior to microscopic examination e. Overexpression of differentially expressed genes identified in nonpathogenic and pathogenic entamoeba histolytica clones allow identification of new pathogenicity factors involved in amoebic liver abscess. It is the third leading parasite cause of death in the developing countries. Entamoeba histolytica, the causative agent of amebiasis, was first described in 1875. Morphology entamoeba histolytica occurs in 3 forms trophozoite precyst cyst 4.
General description entamoeba histolytica is an ameba that feeds on cells in the human colon. Identification of entamoeba histolytica trophozoites in fresh. Entamoeba histolytica, the causative agent of amebiasis, is a protozoan parasite that accounts for an estimated 100,000 annual deaths globally. However, it is not a legal authority for statutory or regulatory purposes. Entamoeba histolytica is well recognized as a pathogenic ameba, associated with intestinal and extraintestinal infections. Reaction conditions were optimized to combine the forward primer entaf with each. It feeds mainly on the tissues of the intestinal wall and often produces severe ulcers and abscesses. With the exception of entamoeba gingivalis, which lives in the mouth, and e. Molecular differentiation of entamoeba histolytica.
1268 1004 646 346 801 1290 344 1111 1271 911 1072 161 932 1485 266 1109 1326 1120 207 1115 1081 1158 941 425 512 1336 1241 1140 1427 1397 1227 1035 1224