Factors Associated with the Detection of<i>Entamoeba Histolytica</i>in Homosexual Men

Law, Carmella; Walker, John C.; Qassim, Mohamed H

doi:10.1177/095646249100200507

Cited by 19 publications

(12 citation statements)

References 9 publications

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“…On the basis of the close social and economic relationship between Japan and Thailand and the fact that (i) sexual intercourse between homosexual men is closely associated with both HIV and amebic infections and (ii) comparison of genotypes between Thai and Japanese HIV strains indicates that a proportion of Japanese HIV strains were imported from Thailand (19,21,25,37,40), we hypothesized that the Japanese and Thai E. histolytica isolates might reveal a similar spectrum of genotypes that is indicative of similarities in the population structures of the E. histolytica strains between the two countries. However, our results appeared to argue against this hypothesis.…”

Section: Discussionmentioning

confidence: 99%

Geographic Diversity among Genotypes of Entamoeba histolytica Field Isolates

et al. 2003

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It has been known that only 5 to 10% of those infected with Entamoeba histolytica develop symptomatic disease. However, the parasite and the host factors that determine the onset of disease remain undetermined. Molecular typing by using polymorphic genetic loci has been proven to aid in the close examination of the population structure of E. histolytica field isolates in nature. In the present study, we analyzed the genetic polymorphisms of two noncoding loci (locus 1-2 and locus 5-6) and two protein-coding loci (chitinase and serine-rich E. histolytica protein [SREHP]) among 79 isolates obtained from different geographic regions, mainly Japan, Thailand, and Bangladesh. When the genotypes of the four loci were combined for all isolates that we have analyzed so far (overlapping isolates from mass infection events were excluded), a total of 53 different genotypes were observed among 63 isolates. The most remarkable and extensive variations among the four loci was found in the SREHP locus; i.e., 34 different genotypes were observed among 52 isolates. These results demonstrate that E. histolytica has an extremely complex genetic structure independent of geographic location. Our results also show that, despite the proposed transmission of other sexually transmitted diseases, including human immunodeficiency virus infection, from Thailand to Japan, the spectra of the genotypes of the E. histolytica isolates from these two countries are distinct, suggesting that the major E. histolytica strains prevalent in Japan at present were likely introduced from countries other than Thailand. Although the genetic polymorphism of the SREHP locus was previously suggested to be closely associated with the clinical presentation, e.g., colitis or dysentery and liver abscess, no association between the clinical presentation and the SREHP genotype at either the nucleotide or the predicted amino acid level was demonstrated.

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Section: Discussionmentioning

confidence: 99%

Geographic Diversity among Genotypes of Entamoeba histolytica Field Isolates

et al. 2003

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“…Entamoeba histolytica acquisition is via the fecal-oral route. In confined populations (e.g., men who have sex with men [MSM] visiting sex-on-premises venues), carriage rates are significantly higher than in the general population once the organism has been established secondary to various oral-anal sexual practices (173,254,274). As the risks for HIV acquisition and parasite acquisition in these environments overlap, apparent associations between E. histolytica and immunosuppression exist.…”

Section: Entamoeba Histolyticamentioning

confidence: 99%

Clinical Significance of Enteric Protozoa in the Immunosuppressed Human Population

et al. 2009

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SUMMARY Globally, the number of immunosuppressed people increases each year, with the human immunodeficiency virus (HIV) pandemic continuing to spread unabated in many parts of the world. Immunosuppression may also occur in malnourished persons, patients undergoing chemotherapy for malignancy, and those receiving immunosuppressive therapy. Components of the immune system can be functionally or genetically abnormal as a result of acquired (e.g., caused by HIV infection, lymphoma, or high-dose steroids or other immunosuppressive medications) or congenital illnesses, with more than 120 congenital immunodeficiencies described to date that either affect humoral immunity or compromise T-cell function. All individuals affected by immunosuppression are at risk of infection by opportunistic parasites (such as the microsporidia) as well as those more commonly associated with gastrointestinal disease (such as Giardia). The outcome of infection by enteric protozoan parasites is dependent on absolute CD4+ cell counts, with lower counts being associated with more severe disease, more atypical disease, and a greater risk of disseminated disease. This review summarizes our current state of knowledge on the significance of enteric parasitic protozoa as a cause of disease in immunosuppressed persons and also provides guidance on recent advances in diagnosis and therapy for the control of these important parasites.

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“…In another study, Law et al (8) reported a 37% prevalence of Entamoeba in men who have sex with men. However, these studies did not differentiate E. histolytica from E. dispar or E. moshkovskii.…”

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confidence: 99%

“…To date, several microscopy-based epidemiological surveys to study the prevalence of E. histolytica and E. dispar have been performed in different parts of Australia, but they were carried out without using molecular methods to accurately identify the presence of individual species. Hence, none of these studies have determined the true presence of E. histolytica, E. dispar, or E. moshkovskii (8,14).…”

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PCR Detection of Entamoeba histolytica , Entamoeba dispar , and Entamoeba moshkovskii in Stool Samples from Sydney, Australia

et al. 2007

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This study investigated the presence of Entamoeba histolytica, Entamoeba dispar, and Entamoeba moshkovskii in stool samples from a patient population in Sydney, Australia. Stool samples were tested by microscopy and PCR. Five patients were found with E. histolytica infections, while E. dispar and E. moshkovskii were observed in 63 (70.8%) and 55 (61.8%) patients, respectively, by PCR. This is the first study in Australia using molecular techniques to determine the presence of E. histolytica, E. dispar, and E. moshkovskii.The genus Entamoeba comprises six species (Entamoeba histolytica, Entamoeba dispar, Entamoeba moshkovskii, Entamoeba poleki, Entamoeba coli, and Entamoeba hartmanni) that live in the human intestinal lumen. E. histolytica, E. dispar, and E. moshkovskii are morphologically identical but are different biochemically and genetically (1,2,3,5,6). Although E. histolytica is recognized as a pathogen, the ability of the other two species to cause disease is unclear. E. moshkovskii, for example, is considered primarily a free-living ubiquitous amoeba found in anoxic sediments (2), and E. dispar is considered primarily a commensal of the human gut (3,5).Early studies of amebiasis in Australia have reported that the incidence of Entamoeba species varies from 1 to 4% in urban and rural communities, respectively (14). In another study, Law et al. (8) reported a 37% prevalence of Entamoeba in men who have sex with men. However, these studies did not differentiate E. histolytica from E. dispar or E. moshkovskii. The prevalence of E. histolytica, E. dispar, and E. moshkovskii (hereafter called the E complex) in the Australian population therefore remains unknown. The present study investigated the presence of the E complex in clinical samples by microscopy and PCR directly in stool samples collected from patients presenting with gastrointestinal symptoms.All of the stool specimens (from a diverse patient population) submitted to the Department of Microbiology at St. Vincent's Hospital, Sydney, Australia, during January 2003 to June 2006 for investigation of diarrhea were included in this study. Specimens from outpatients were collected by the patient and submitted to the laboratory as fresh specimens along with a portion mixed with sodium acetate-acetic acid-formalin (SAF). Specimens from inpatients or received without a portion fixed in SAF were immediately preserved in SAF upon arrival at the laboratory. The SAF-fixed specimens underwent permanent staining with a modified iron-hematoxylin stain according to the manufacturer's recommendations (Fronine, Australia). Patients diagnosed with members of the E complex by microscopy of stained smears underwent further investigations.DNA was extracted from fecal specimens (without fixatives) from patients either fresh or after storage at Ϫ20°C (immediately frozen upon arrival at the laboratory). Briefly, the stool sample (200 mg) was washed twice with 1 ml of sterile phosphate-buffered saline (pH 7.2), centrifuged for 5 min at 14,000 ϫ g, and DNA extracted according t...

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Factors Associated with the Detection ofEntamoeba Histolyticain Homosexual Men

Cited by 19 publications

References 9 publications

Geographic Diversity among Genotypes of Entamoeba histolytica Field Isolates

Geographic Diversity among Genotypes of Entamoeba histolytica Field Isolates

Clinical Significance of Enteric Protozoa in the Immunosuppressed Human Population

PCR Detection of Entamoeba histolytica , Entamoeba dispar , and Entamoeba moshkovskii in Stool Samples from Sydney, Australia

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