الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
This essay is a comprehensive review on the protozoan amoebae, discussing the different types of amoebae which cause both intestinal and extra-intestinal human infections like liver, lung, brain and skin. The morphological differences between intestinal types (parasitic and commensals) like E. histolytica, E. dispar, E. coli, E. hartmani, Endolimax nani and E. gingivalis (which is present in the oral cavity) as well as the free living types (Naegleria and Acanthamoeba spp.) were clarified. The taxonomy, morphology and different stages of these parasites (by light microscopy as well as the scanning and transmission electron microscopy) were discussed. The recent use of electron microscopy discovered the ultrastructural organelles of these organisms, in addition to the methods of nutrition and excretion of waste products (which were not previously known), as well as the ultrastructure of the outer membrane of trophozoites and cysts. However, it was noticed that electron microscopic studies were not able to illustrate definite ultrastructural features that can facilitate the differentiation between these parasites. The review also discussed the pathogenicity of the different strains of E. histolytica (some strains are non pathogenic while others are moderately and more pathogenic and invasive) and it clarified the extraintestinal infection leading to serious complications of the liver,
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brain and other tissues. Moreover, it discussed three virulence factors of E. histolytica trophozoite which enable it to penetrate the intestinal mucous membrane and the possibilities of presence other factors are not yet known. It was recommended that future studies should be done on these factors which may explain the causes of increased invasive power of some strains and phenotypes into the large intestinal mucus membrane and to reach other vital organs as the liver and brain leading to severe morbidity.
The epidemiology of amebae and its prevalence in Egypt and worldwide were discussed, however it was difficult to know the true prevalence of E. histolytica due to the similarity of its pathogenic strains and the non pathogenic E. dispar and E. moshkoviskii, and this was mainly because most researches depend on the microscopic examination of these parasites without stain or with Iodine or Hematoxyline stains or with the help of cultures. On the other hand, the recent researches used the molecular biological methods which were only helpful to distinguish between these types and enabled us to discover some cases infected by E. moshkoviskii in Bangladesh, Tunis and Australia.
Furthermore, the recent advances in the field of the immunological response of human body for E. histolytica infection (the cellular and humoral immunity) was discussed as well as the discovery and
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description of the amoebic genome which was followed by a lot of trials to produce anti-amoebiasis vaccine, however this is still not an achievable target. This review discussed also the advances in the field of serological and immunological diagnosis of amoebic infection using PCR, isoenzymes and microarray techniques. The present work also discussed the treatment of amoebic infections as well as the causes of resistance to antiamoebic drugs.
Different types of free living amoebas, their ultrastructural morphology using electron microscopy, the methods of diagnosis, as well as diseases caused by them particularly in immunocompromized individuals, clinical picture of brain invasion which may be followed by severe complications and death and their prevention were discussed in a separate part in this review.
Amoebic studies in Egypt were also an area of focus in the current review describing the different strains of amoebae which are found in Egypt, diagnosis and treatment. It was noticed that there is few researches in the field of differentiating E. histolytica, E. dispar and E. moshkoviskii. So we recommend more studies to be done on this point later on. In this study, we could not trace any work in the field of amoebiasis from all Upper Egyptian governorates, in spite of the abundance of the risk factors for amoebic infection in most villages as
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well as some urbanized districts where sewage pollution of drinking water is not uncommon putting in mind that E.moshkovskii was essentially isolated from sewage contents. In such conditions, it is surprising that this parasite was not recorded from Egypt.