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PubMedDate not supplied

Cyst production and transmission of Entamoeba and Endolimax.

We studied the cyst production of 340 asymptomatic carriers with single or mixed infections of Entamoeba histolytica/Entamoeba dispar, Endolimax nana and Entamoeba coli. It was found that the main source of transmission was a small group of 37 (10.9%) carriers who produced 70.2% of all cysts. Gender was an important factor for cyst production of Ent. histolytica/Ent. dispar, since males produced 6-fold more cysts than females. Females produced 'large' (13-15 microns) Ent. histolytica/Ent. dispar cysts and males small (10-12 microns) cysts when concentration was > 2000 cysts/g. When concentration was < 2000 cysts/g, cysts were the same size for both sexes (11.6 +/- 0.3 microns). In Ent. coli infections, an inverse relationship between the number and size of cyst was found for both sexes. Cysts of End. nana were not affected by gender or cyst concentration. Following cyst production by a carrier infected with Ent. coli and Ent. histolytica for 28 days, we identified synchronized cycles of cyst production for both species. Altogether, these data suggest that cyst-mediated transmission is a highly regulated process in which synchronization among different species and gender of the host have an important role in transmission.

Amebiasis↗
PubMedDate not supplied

Species-specific field testing of Entamoeba spp. in an area of high endemicity.

Entamoeba histolytica has been separated in recent years into 2 morphologically identical species: the apathogenic E. dispar and the pathogenic E. histolytica, only the latter being pathogenic. Although various laboratory techniques allow discrimination between the 2 species there is a lack of field data about the suitability of available diagnostic tests for use in epidemiological studies and few epidemiological studies using species-specific diagnosis have been performed at community level in endemic areas, especially in sub-Saharan Africa. We conducted a repeated cross-sectional study of 967 schoolchildren in central Côte d'Ivoire to compare and evaluate light microscopy, 2 different antigen detection assays, and one polymerase chain reaction (PCR) assay. Microscopy and a non-specific antigen capture Entamoeba enzyme-linked immunosorbent assay (ELISA) were used for the primary screening of all children (time t0). The prevalence of the E. histolytica/E. dispar species complex at t0 was 18.8% by single microscopical examination and 31.4% using the non-specific ELISA. Approximately 2 months after the initial screening, fresh stool specimens were collected on 2 consecutive days (t1 and t2) from (i) all the children who were positive by microscopy at t0 (n = 182) and (ii) 155 randomly selected children who were negative at the primary screening. These samples were tested with a second antigen detection ELISA specific for E. histolytica (n = 238) and with a species-specific PCR assay (n = 193). The second and third examinations (t1 and t2) revealed an additional 43 infections with the species complex E. histolytica/E. dispar, so that the cumulative microscopical prevalence for t1 and t2 was 27.7%. The overall prevalence of E. histolytica by species-specific ELISA antigen detection was low (0.83%), while the prevalence of E. dispar was 15%. When analysing only microscopically positive samples by PCR (n = 129), the ratio E. histolytica: E. dispar was very low (1:46), suggesting that the vast majority of Entamoeba infections in this area were apathogenic. Both species-specific tests performed well but the ELISA was easier to use for large-scale field screening.

Adolescent↗
PubMedDate not supplied

Evaluation of newer diagnostic methods for the detection and differentiation of Entamoeba histolytica in an endemic area.

We evaluated the colorimetric polymerase chain reaction (PCR)-based method for the detection and differentiation of Entamoeba spp. and compared the efficacy of E. histolytica-specific antigen detection in faeces with the detection of specific antibodies to E. histolytica-specific antigen in faeces, by enzyme-linked immunosorbent assay. Faecal samples were obtained from patients attending hospital in Chandigarh, India, from March 2001 to February 2002. The PCR-based colorimetric method was found to be the most sensitive (100%) and it could differentiate between pathogenic and non-pathogenic Entamoeba spp. The present study also emphasized that the antigen detection system may prove to be a better diagnostic tool than the antibody detection system in endemic areas.

Animals↗
PubMedDate not supplied

Royal Society of Tropical Medicine and Hygiene Meeting at Manson House, London, 19 February 1998. Amoebic disease. Entamoeba histolytica and E. dispar: comparison of molecules considered important for host tissue destruction.

Entamoeba histolytica and E. dispar are genetically distinct but closely related protozoan species. Both colonize the human gut but only E. histolytica is able to invade tissues and cause disease. Comparison of the 2 species may help to elucidate the specific mechanisms involved in the pathogenicity of E. histolytica. During the last few years, various amoeba molecules considered to be important for pathogenic tissue invasion have been identified and characterized, such as a galactose-inhibitable surface lectin, pore-forming peptides and cysteine proteinases. This review summarizes present knowledge about the structure and function of these molecules, with emphasis on the differences between E. histolytica and E. dispar.

Animals↗
PubMedDate not supplied

Royal Society of Tropical Medicine and Hygiene meeting at Manson House, London, 19 February 1998. Amoebic disease. Entamoeba dispar, an organism reborn.

Entamoeba dispar was described by Emile Brumpt in 1925, and was promptly dismissed as a synonym of E. histolytica by almost all his contemporaries. In the 1970s, however, evidence began to accumulate indicating that Brumpt may have been correct and E. dispar is now accepted as a distinct species. This review introduces the organism's history and briefly summarizes what we currently know about its biology. The acceptance of E. dispar has profound implications for our understanding of the epidemiology of amoebiasis and, ultimately, may give us an insight into what makes E. histolytica a pathogen.

Animals↗
PubMed2003

Oral cavity as a potential source of infections in recipients with diabetes mellitus.

Our previous observations showed alterations of oral cavity status among hemodialyzed patients and kidney allograft recipients as well as differences in the prevalence and composition of microorganisms occurring in the mouths of patients. In the present work, we analysed the results of oral cavity examinations, the identification of microorganisms, and the assessment of their importance to kidney allograft recipients or hemodialyzed patients with diabetes mellitus, in comparison with nondiabetic recipients, dialyzed patients, and control patients.

Adult↗
PubMed1984

Entamoeba histolytica cyst passers: clinical features and outcome in untreated subjects.

To examine whether Entamoeba histolytica is the cause of a variety of intestinal disorders, as often implicated, a two-part study was conducted. In part 1, 184 patients attending a gastroenterology clinic and needing a sigmoidoscopy had a rectal biopsy specimen and a stool sample cultured for E histolytica. Part of the biopsy specimen was examined histologically. In addition, serum was tested for antibody to E histolytica. 34 (18.7%) patients were culture positive. There was no correlation between the culture results and patients' symptoms except for diarrhoea, which was more common in the culture-negative group, or with histological or serological findings. In the second part of the study, 15 culture-positive patients were followed up untreated for a mean (+/- SD) of 8.6 (+/- 4.9) months, range 1-18. In all 15 patients spontaneous eradication of the parasite occurred, and in none did symptoms of invasive amoebiasis develop. Thus E histolytica seems not to be responsible for many of the bowel complaints commonly attributed to it. In these cyst passers the cysts are probably incidental to an irritable bowel syndrome or some other organic disease. There seems to be little justification for treating cyst passers since eradication of the parasite occurs spontaneously and the danger of invasive amoebiasis is negligible. Such a practice would result in an enormous saving on the cost of drugs.

Amebiasis↗
PubMed1985

Seroepidemiological study of antibody responses to the zymodemes of Entamoeba histolytica.

In 303 apparently healthy subjects and 54 patients with confirmed invasive amoebiasis amoebae were isolated where possible, and Entamoeba histolytica was classified into its various zymodems. 20% of the healthy subjects were antibody-positive; 17 healthy subjects proved to be symptomless carriers of pathogenic zymodemes and, like patients with invasive disease, all these were seropositive. Furthermore, of subjects infected with pathogenic zymodemes 94-100% were strongly seropositive, compared with 2-4% of subjects with non-pathogenic zymodemes. Pathogenic zymodemes are therefore believed to be in constant contact with the host's tissues, even in symptom-free individuals; the presence of these potentially invasive organisms is thought to be directly related to the seropositivity in a given population, and seroepidemiological surveys would therefore provide information only on the distribution of this form of the parasite. Quantitative serological data constitute valuable information on the endemicity of an area, and the results will gain reliability from use of two complementary tests instead of one.

Antibody Formation↗
PubMed1986

Is Entamoeba histolytica in homosexual men a pathogen?

Entamoeba histolytica (EH) in homosexual men is generally considered to be pathogenic. To test this hypothesis, the generally accepted features of invasion (haematophagous trophozoites in faeces; high-titre serum antibody; moderate to severe acute inflammatory change; and presence of EH in the mucosa on rectal biopsy) and the zymodeme pattern of cultured trophozoites were assessed in twenty-three EH excretors and eleven control homosexual men. No trophozoites or antibody to EH were found in either group. When other pathogens were excluded, no patient in either group had severe, acute histopathological proctitis. Moderately severe change was seen in 38% of EH excretors and 18% of controls (not significant). All the zymodemes were non-pathogenic. Successful eradication of EH did not result in even a trend towards normalisation of the moderate inflammatory histopathology. There are, therefore, no data here to suggest that EH is a pathogen in homosexual men.

Adult↗