<P> In the vast majority of cases, infection is asymptomatic and the carrier is unaware they are infected . However, in an estimated 10% of cases E. histolytica causes disease . Once the trophozoites are excysted they colonize the large bowel, remaining on the surface of the mucus layer and feeding on bacteria and food particles . Occasionally, and in response to unknown stimuli, trophozoites move through the mucus layer where they come in contact with the epithelial cell layer and start the pathological process . E. histolytica has a lectin that binds to galactose and N - acetylgalactosamine sugars on the surface of the epithelial cells, The lectin normally is used to bind bacteria for ingestion . The parasite has several enzymes such as pore forming proteins, lipases, and cysteine proteases, which are normally used to digest bacteria in food vacuoles but which can cause lysis of the epithelial cells by inducing cellular necrosis and apoptosis when the trophozoite comes in contact with them and binds via the lectin . Enzymes released allow penetration into intestinal wall and blood vessels, sometimes on to liver and other organs . The trophozoites will then ingest these dead cells . This damage to the epithelial cell layer attracts human immune cells and these in turn can be lysed by the trophozoite, which releases the immune cell's own lytic enzymes into the surrounding tissue, creating a type of chain reaction and leading to tissue destruction . This destruction manifests itself in the form of an' ulcer' in the tissue, typically described as flask - shaped because of its appearance in transverse section . This tissue destruction can also involve blood vessels leading to bloody diarrhea, amebic dysentery . Occasionally, trophozoites enter the bloodstream where they are transported typically to the liver via the portal system . In the liver a similar pathological sequence ensues, leading to amebic liver abscesses . The trophozoites can also end up in other organs, sometimes via the bloodstream, sometimes via liver abscess rupture or fistulas . In all locations, similar pathology can occur . </P> <P> E. histolytica may modulate the virulence of certain human viruses and is itself a host for its own viruses . </P> <P> For example, 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 . </P> <P> A burst of research on viruses of E. histolytica stems from a series of papers published by Diamond et al. from 1972 to 1979 . In 1972, they hypothesized two separate polyhedral and filamentous viral strains within E. histolytica that caused cell lysis . Perhaps the most novel observation was that two kinds of viral strains existed, and that within one type of amoeba (strain HB - 301) the polyhedral strain had no detrimental effect but led to cell lysis in another (strain HK - 9). Although Mattern et al. attempted to explore the possibility that these protozoal viruses could function like bacteriophages, they found no significant changes in Entamoeba histolytica virulence when infected by viruses . However, no newer published research has been conducted on this species since . </P>

What is the common name for entamoeba histolytica