Community hub
Recent from talks
Knowledge base stats:
Talk channels stats:
Members stats:
Entamoeba histolytica
Entamoeba histolytica is an anaerobic parasitic amoebozoan, part of the genus Entamoeba. Predominantly infecting humans and other primates causing amoebiasis, E. histolytica is estimated to infect about 35-50 million people worldwide. E. histolytica infection is estimated to kill more than 55,000 people each year. Previously, it was thought that 10% of the world population was infected, but these figures predate the recognition that at least 90% of these infections were due to a second species, E. dispar. Mammals such as dogs and cats can become infected transiently, but are not thought to contribute significantly to transmission.
The word histolysis literally means disintegration and dissolution of organic tissues.
The active (trophozoite) stage exists only in the host and in fresh loose feces; cysts survive outside the host in water, in soils, and on foods, especially under moist conditions on the latter. The infection can occur when a person puts anything into their mouth that has touched the feces of a person who is infected with E. histolytica, swallows something, such as water or food, that is contaminated with E. histolytica, or swallows E. histolytica cysts (eggs) picked up from contaminated surfaces or fingers. The cysts are readily killed by heat and by freezing temperatures; they survive for only a few months outside of the host. When cysts are swallowed, they cause infections by excysting (releasing the trophozoite stage) in the digestive tract. The pathogenic nature of E. histolytica was first reported by Fedor A. Lösch in 1875, but it was not given its Latin name until Fritz Schaudinn described it in 1903. E. histolytica, as its name suggests (histo–lytic = tissue destroying), is pathogenic; infection can be asymptomatic, or it can lead to amoebic dysentery or amoebic liver abscess. Symptoms can include fulminating dysentery, bloody diarrhea, weight loss, fatigue, abdominal pain, and amoeboma. The amoeba can 'bore' into the intestinal wall, causing lesions and intestinal symptoms, and it may reach the bloodstream or peritoneal cavity. From there, it can reach vital organs of the human body, usually the liver, but sometimes the lungs, brain, and spleen. A common outcome of this invasion of tissues is a liver abscess, which can be fatal if untreated. Ingested red blood cells are sometimes seen in the amoeba cell cytoplasm.
Poor sanitary conditions are known to increase the risk of contracting amebiasis E. histolytica. In the United States, there is a much higher rate of amebiasis-related mortality in California and Texas (this might be caused by the proximity of those states to E. histolytica-endemic areas, such as Mexico), parts of Latin America, and Asia. E. histolytica is also recognized as an emerging sexually transmissible pathogen, especially in male homosexual relations, causing outbreaks in non-endemic regions. As such, high-risk sex behaviour is also a potential source of infection. Although it is unclear whether there is a causal link, studies indicate a higher chance of being infected with E. histolytica if one is also infected with human immunodeficiency virus (HIV).
The E. histolytica genome was sequenced, assembled, and automatically annotated in 2005. The genome was reassembled and reannotated in 2010. The 20 million basepair genome assembly contains 8,160 predicted genes; known and novel transposable elements have been mapped and characterized, functional assignments have been revised and updated, and additional information has been incorporated, including metabolic pathways, Gene Ontology assignments, curation of transporters, and generation of gene families. The major group of transposable elements in E. histolytica are non-LTR retrotransposons. These have been divided in three families called EhLINEs and EhSINEs (EhLINE1,2,3 and EhSINE1,2,3). EhLINE1 encodes an endonuclease (EN) protein (in addition to reverse transcriptase and nucleotide-binding ORF1), which has similarity with bacterial restriction endonuclease. This similarity with bacterial protein indicates that transposable elements have been acquired from prokaryotes by horizontal gene transfer in this protozoan parasite.
The genome of E. histolytica has been found to have snoRNAs with opisthokont-like features. The E. histolytica U3 snoRNA (Eh_U3 snoRNA) has shown sequence and structural features similar to Homo sapiens U3 snoRNA.
E. histolytica may modulate the virulence of certain human viruses and is itself a host for its own viruses.[citation needed]
For example, acquired immunodeficiency syndrome (AIDS) accentuates the damage and pathogenicity of E. histolytica. On the other hand, cells infected with HIV are often consumed by E. histolytica. Infective HIV remains viable within the amoeba, although there has been no proof of human reinfection from amoeba carrying this virus.
Hub AI
Entamoeba histolytica AI simulator
(@Entamoeba histolytica_simulator)
Entamoeba histolytica
Entamoeba histolytica is an anaerobic parasitic amoebozoan, part of the genus Entamoeba. Predominantly infecting humans and other primates causing amoebiasis, E. histolytica is estimated to infect about 35-50 million people worldwide. E. histolytica infection is estimated to kill more than 55,000 people each year. Previously, it was thought that 10% of the world population was infected, but these figures predate the recognition that at least 90% of these infections were due to a second species, E. dispar. Mammals such as dogs and cats can become infected transiently, but are not thought to contribute significantly to transmission.
The word histolysis literally means disintegration and dissolution of organic tissues.
The active (trophozoite) stage exists only in the host and in fresh loose feces; cysts survive outside the host in water, in soils, and on foods, especially under moist conditions on the latter. The infection can occur when a person puts anything into their mouth that has touched the feces of a person who is infected with E. histolytica, swallows something, such as water or food, that is contaminated with E. histolytica, or swallows E. histolytica cysts (eggs) picked up from contaminated surfaces or fingers. The cysts are readily killed by heat and by freezing temperatures; they survive for only a few months outside of the host. When cysts are swallowed, they cause infections by excysting (releasing the trophozoite stage) in the digestive tract. The pathogenic nature of E. histolytica was first reported by Fedor A. Lösch in 1875, but it was not given its Latin name until Fritz Schaudinn described it in 1903. E. histolytica, as its name suggests (histo–lytic = tissue destroying), is pathogenic; infection can be asymptomatic, or it can lead to amoebic dysentery or amoebic liver abscess. Symptoms can include fulminating dysentery, bloody diarrhea, weight loss, fatigue, abdominal pain, and amoeboma. The amoeba can 'bore' into the intestinal wall, causing lesions and intestinal symptoms, and it may reach the bloodstream or peritoneal cavity. From there, it can reach vital organs of the human body, usually the liver, but sometimes the lungs, brain, and spleen. A common outcome of this invasion of tissues is a liver abscess, which can be fatal if untreated. Ingested red blood cells are sometimes seen in the amoeba cell cytoplasm.
Poor sanitary conditions are known to increase the risk of contracting amebiasis E. histolytica. In the United States, there is a much higher rate of amebiasis-related mortality in California and Texas (this might be caused by the proximity of those states to E. histolytica-endemic areas, such as Mexico), parts of Latin America, and Asia. E. histolytica is also recognized as an emerging sexually transmissible pathogen, especially in male homosexual relations, causing outbreaks in non-endemic regions. As such, high-risk sex behaviour is also a potential source of infection. Although it is unclear whether there is a causal link, studies indicate a higher chance of being infected with E. histolytica if one is also infected with human immunodeficiency virus (HIV).
The E. histolytica genome was sequenced, assembled, and automatically annotated in 2005. The genome was reassembled and reannotated in 2010. The 20 million basepair genome assembly contains 8,160 predicted genes; known and novel transposable elements have been mapped and characterized, functional assignments have been revised and updated, and additional information has been incorporated, including metabolic pathways, Gene Ontology assignments, curation of transporters, and generation of gene families. The major group of transposable elements in E. histolytica are non-LTR retrotransposons. These have been divided in three families called EhLINEs and EhSINEs (EhLINE1,2,3 and EhSINE1,2,3). EhLINE1 encodes an endonuclease (EN) protein (in addition to reverse transcriptase and nucleotide-binding ORF1), which has similarity with bacterial restriction endonuclease. This similarity with bacterial protein indicates that transposable elements have been acquired from prokaryotes by horizontal gene transfer in this protozoan parasite.
The genome of E. histolytica has been found to have snoRNAs with opisthokont-like features. The E. histolytica U3 snoRNA (Eh_U3 snoRNA) has shown sequence and structural features similar to Homo sapiens U3 snoRNA.
E. histolytica may modulate the virulence of certain human viruses and is itself a host for its own viruses.[citation needed]
For example, acquired immunodeficiency syndrome (AIDS) accentuates the damage and pathogenicity of E. histolytica. On the other hand, cells infected with HIV are often consumed by E. histolytica. Infective HIV remains viable within the amoeba, although there has been no proof of human reinfection from amoeba carrying this virus.