Entamoeba

Entamoeba histolytica infection is the third-greatest parasitic disease responsible for death in the world. Wild rats harbouring E. histolytica can be the possible reservoir hosts for human amoebiasis. There were numerous studies on prevalence of intestinal parasites among wild rats in Malaysia but none has reported E. histolytica. Rats were captured from Sentul and Chow Kit areas, Kuala Lumpur, Malaysia. The preserved stool samples were used for microscopy examination and molecular analysis. Out of 137 samples collected, 12 were positive for E. histolytica / E. dispar / E. moshkovskii microscopically. Two E. histolytica (1.4%), 1 E. dispar (0.7%) and 6 mixed infections of E. histolytica and E. dispar (4.3%) were detected using PCR. This is the first report of molecular detection of E. histolytica/dispar infection among wild rats in Malaysia. This study provides useful information about the potential risks of zoonotic agents and the importance of developing control measures to preve...

Entamoeba moshkovskii and Entamoeba dispar are impossible to differentiate microscopically from the pathogenic species Entamoeba histolytica. There are limited data on the prevalence of these commensal parasites in Iran. We utilized a single-round PCR assay to determine the prevalence of E. moshkovskii, E. dispar, and E. histolytica in stool samples from Iranian patients infected with gastrointestinal disorders. After culturing of microscopy-positive isolates and extraction of DNA, PCR was carried out to differentiate the Entamoeba isolates. Out of 3,825 stool samples examined by microscopy, 58 specimens (1.52%) were infected with E. histolytica, E. dispar, or E. moshkovskii. By PCR, 2 E. histolytica (3.45%), 53 E. dispar (91.37%), 2 E. moshkovskii (3.45%), and one mixed E. dispar/E. moshkovskii infection (1.73%) were detected. In view of the reporting of E. moshkovskii in this study in Iran and the difficulty in discriminating this ameba from two similar Entamoeba spp. by microscop...

An approximately 11-mo-old female giant anteater (Myrmecophaga tridactyla) exhibited anorexia, lethargy, hypothermia, depression, and minimal response to external stimuli. Radiography and ultrasonography revealed an enlarged heart, with free gas and fluid in the abdomen. Abdominocentesis produced a clear brown fluid with an acute to subacute septic suppurative exudate. Cardiac ultrasonography revealed a dilated, thin-walled left ventricle with a comparatively low fractional shortening. Despite intensive supportive care, the anteater died. Postmortem findings included gastric ulceration with perforation near the pylorus. Entameba spp. and Acanthamoeba spp. were both identified in large numbers at the site of the gastric ulceration and perforation.

The aim and the background of this paper was to investigate how ancient primitive eukaryotes evolved to the successful parasites they are today. In preparing this work, the most significant literature of the last years has been studied. We expand it by the results of our own research. Results and conclusion: Anaerobic single-celled eukaryotes, such as
Entamoeba invadens and Giardia lamblia , became successful invasive pathogens by using mechanisms inherited from the common ancestor (LECA). As described in previous papers pathogen protists have a surprising stem cell network (ancient
protolineage) controlled by intrinsic and extrinsic mechanisms of cell conversion and differentiation inherited from the ancestor. Mechanisms leading to pathogenicity were not acquired after the organisms became parasitic, they were present before the single-celled organisms switched to parasitism. Only organisms possessing an extended ancestral stem cell system capable of switching between most oxidative
(MO) and most hypoxic (MH) niches by changing metabolic pathways and antigenicity could develop into successful invasive pathogens like Entamoeba or Giardia. Related organisms not conserving all ancestral features evolved to become luminal commensals or free-living protists

The appearance of stem cells was a major evolutionary advance. It remains however unknown which ancestral biosystem evolved first for stemness and under what conditions. The purpose of this report is to provide an overview of the evolutionary origin of stem cells. It summarizes the current knowledge and dogmas on the origin of stem
cell evolution. Understanding stemness in metazoans illustrates the basic principles of lineage organization and stem cell hierarchy in ancient single-celled eukaryotes.

Background: In this study, a total of 426 human faecal samples were examined for the presence of Entamoeba histolytica, Entamoeba dispar, Entamoeba moshkovskii infection via a combination of microscopic examination and nested polymerase chain reaction (PCR) targeting 16S ribosomal RNA of Entamoeba species.

Methods: Faecal sample were collected from 426 participants in five rural villages in Peninsular Malaysia. The faecal samples were processed by direct wet smear and formalin ethyl acetate concentration technique followed by iodine staining and examined via microscopy for the presence of Entamoeba species and other intestinal parasites. Microscopically positive samples for Entamoeba species cysts were further characterized using a Nested Polymerase Chain Reaction (Nested-PCR) targeting 16S-like ribosomal RNA gene. The data entry and analysis was carried out using the SPSS software (Statistical Package for the Social Sciences) program for Windows version 17 (SPSS, Chicago, IL, USA).

Results: Based on single faecal examination, overall prevalence of Entamoeba infection was 17.6% (75/426). Females (19.1%) were more commonly infected compared to males (15.9%). Comparison by age groups showed that adults (23.9%) had higher infection rates than children (15.3%). The PCR results showed that 52 out of 75 microscopy positive samples successfully generated species-specific amplicons. The infection with E. histolytica (75.0%; 39/52) was the most common, followed by E. dispar (30.8%; 18/52) and E. moshkovskii (5.8%; 3/52). Of these, 33 (63.5%) were shown to contain only E. histolytica, 10 (19.2%) contained E. dispar and 3 (5.8%) contained only E. moshkovskii. Mixed infection with E. histolytica and E. dispar was found in 6 (11.5%) samples.

The present study essentially emphasized the benefit of molecular techniques in discriminating the
pathogenic Entamoeba species from the non-pathogenic for accurate diagnosis and better management of amoebiasis.
The presence of E. moshkovskii is of great public health concern as it was the first time it has been reported in Malaysia.

1. Arch Med Res. 2000 Jul-Aug;31(4 Suppl):S34-5. Prevalence of Entamoeba histolytica and Entamoeba dispar in a highly endemic rural population. Ramos F, Valdez E, Morán P, González E, Padilla G, Gómez A, Ramiro M, Melendro EI, Muñoz O, Clark CG, Ximénez C. ...

Intestinal permeability (IP) studies using some macromolecules have been assumed to demonstrate the intactness of intestinal mucosa. The aim of the present study is to determine the changes in IP among patients with protozoan infections. Thirty nine patients with protozoan infections and ten healthy controls were enrolled in the study. Protozoa were diagnosed by Native-lugol, Richie and Trichrome staining of faeces. IP was evaluated by diethyl triamine penta acetic acid labeled with 99m Technetium (99mTc labeled DTPA) assay. The IP was found to have increased in patients with protozoan infections compared with control patients (7.20±5.52 vs. 4.47±0.65%, P=0.0017). The IP values were 9.91±10.05% in Giardia intestinalis group, 6.81±2.25% in Blastocystis hominis group, 5.78±2.84% in Entamoeba coli group. In comparison with the control group, the IP was significantly higher in G. intestinalis and B. hominis patients (P=0.0025, P=0.00037, respectively), but not in E. coli patients. In conclusion, the IP increases in patients with G. intestinalis and B. hominis but not with E. coli infection. This finding supports the view that IP increases during the course of protozoan infections which cause damage to the intestinal wall while non-pathogenic protozoan infections have no effect on IP. The increase in IP in patients with B. hominis brings forth the idea that B. hominis can be a pathogenic protozoan.

Amoebiasis, a disease caused by Entamoeba histolytica, is usually diagnosed by microscopic examination, which does not differentiate the morphologically identical species of the E. histolytica/E. dispar complex. Furthermore, morphologically similar species such as Entamoeba hartmanni contribute to misidentification. Therefore, there is a need for more sensitive and specific methods. This study standardized a multiplex real-time PCR system for E. histolytica and E. dispar and a single real-time PCR for E. hartmanni. The multiplex protocol detected up to 0.0143 pg of E. histolytica DNA and 0.5156 pg of E. dispar DNA, and the average melting temperature (T(m)) was 73 °C and 70 °C, respectively. For E. hartmanni, the T(m) was 73 °C and the amplification was successful down to 0.03 fg of plasmid DNA. Negative controls and other intestinal parasites presented no amplification. Among the 48 samples tested, E. dispar DNA was detected in 37; none exhibited E. histolytica DNA and 11 were nega...

The present study was conducted to investigate the infection of Entamoeba spp by using molecular technique (Quantitative real time polymerase chain reaction) of primers and probes for gene 18S rRNA . The results revealed the presence of Entamoeba histolytica in the percentage (74%) of 200 Entamoeba microscopic positive samples. Also three primers were used in this study for detection the gene of virulence factor of Entamoeba histolytica. The Cysteine protease revealed the high percentage(86.6%) of infection then Amebopore gene (80.35%) whereas Gal/lectin gene gave the lowest (7 5%) ,without significant differences at (p<0.05).

Most parasitic intestinal infestations in humans are sub-clinical and, therefore, they are rarely diagnosed. A number of general, non-specific symptoms of parasitic invasions are often attributed to other diseases. A parasitological examination of feces performed as part of this study confirmed the presence of intestinal parasites in 21.6% of samples. Among the patients who reported 6 different symptoms, the percentage of parasite-positive samples reached 80%. The obtained results suggest that coproscopic tests may establish the diagnosis in unclear cases, particularly in children. Many parasitic invasions are zoonoses and pets owe a reservoir. In view of the above, the results for pet owners and non-pet owners were compared in the study. There was no direct correlation between pet ownership and the incidence of parasitic infections.

Cell differentiation in Entamoeba and Giardia exhibit a great deal of similarity. Unfortunately, both protists were studied over the years mostly under axenic conditions, disregarding the natural micro-ecology of host intestine. Using hypoxic culture sediments with oxygen consuming bacteria (OCB niches) we discovered in E. invadens an ancient stem cell system that shows the same basal mechanisms for stemness
that exist in highly developed stem cell systems too. The ancient stem cells of E. invadens (AnSC) have all standards of the stem cell definition (self renewing and quiescent cells, glycolytic metabolism, stem cell plasticity, reprogramming and induced totipotency recovery, and both induced and autonomous terminal differentiation  indicating that stem cells were developed by the anaerobe proterozoic LECA-as stages of its life cycle-then diverged into all eukaryotes. The more protist stem cell systems we can dechipher the more we will learn about the ancestral protolineage, its cell line hierarchy and basal mechanism of stemness. We assume that Giardia could be a good model system to expand protist stem cell biology. We found in Giardia literature evidence suggesting self renewal and quiescence, plasticity and other stem cell characteristics.
The present study is a reinterpretation of Giardia’s life cycle in the light of current stem cell knowledge. It is hoped this reinterpretation stimulates new developments.