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PubMed1982

The epidemiology of Entamoeba histolytica in a rural and an urban area of Mexico. A pilot survey II.

Stocks of intestinal amoebae grown in monoxenic culture, were compared against each other and against those previously reported from Mexico City. These were isolated from subjects in San Cristobal de las Casas, Chiapas (rural area) and hospital patients in Merida, Yucatan (urban area). Electrophoretic patterns of the four enzymes: glucose phosphate isomerase (GPI), phosphoglucomutase (PGM), L-malate: NADP+ oxido-reductase (oxalacetate-decarboxylating) (ME) and hexokinase (HK) demonstrated the presence of five groups (zymodemes) of Entamoeba histolytica already described from Mexico City, together with two new zymodemes, one of which gave a recognizable pathogenic pattern, whilst the other gave a contradictory pattern. Zymodemes of Entamoeba coli, Entamoeba hartmanni, Iodamoeba buetschlii and Dientamoeba fragilis, previously described were also isolated. One new zymodeme of D. fragilis was demonstrated.

Amebiasis↗
PubMed1983

Safety and efficacy of diphetarsone in the treatment of amoebiasis, non-pathogenic amoebiasis and trichuriasis.

Eighty-nine patients infected with Entamoeba histolytica, non-pathogenic amoebae or Trichuris trichiura were studied prospectively to determine the safety and efficacy of diphetarsone therapy. An additional 75 patients were studied retrospectively to assess further the efficacy of diphetarsone in the treatment of E. histolytica cyst passers. Side effects were noted in 9% and included gastrointestinal upset, lightheadedness and headache. Transient liver function abnormalities were recorded in 5.6%. diphetarsone was completely effective in the treatment of Dientamoeba fragilis, Entamoeba hartmanni, Iodamoeba buetschlii and Trichuris trichiura. 99% of the patients with E. histolytica, 97% of those with E. coli and 98% of those with Endolimax nana were cured.

Adult↗
PubMed1983

Amoebiasis and giardiasis in Bangladesh: parasitological and serological studies.

To determine the prevalence of infections with Entamoeba histolytica and Giardia lamblia in Bangladesh, we screened stool specimens from patients with diarrhoea attending urban (N = 2,246) and a rural (N = 2,791) hospital and a group of healthy urban residents (N = 440). Sera from 200 healthy villagers were also examined for antibody to E. histolytica using the immunofluorescent antibody test. The prevalence of E. histolytica cysts or trophozoites in all groups assessed by examination of a single stool specimen ranged from 0% among infants (less than 1 year) to 34% among healthy adults 30 to 44 years old. G. lamblia was uncommon in infants and found most frequently in urban hospital patients aged five to nine (21%). 12% of one- to two-year-old children had serum antibody to E. histolytica at a titre of 1:40. By age 14 years, 80% of those tested were seropositive, and this prevalence declined thereafter with increasing age. Amoebiasis and giardiasis occur frequently in Bangladeshi populations and the morbidity and mortality associated with these infections need to be assessed.

Adolescent↗
PubMed1984

An outbreak of amoebic infection in a kibbutz population.

The cause of a reported outbreak of abdominal cramps and diarrhoea in a kibbutz in the Western Negev, Israel, was sought. Over 25% of the kibbutz population was found to harbour Entamoeba histolytica, a very high rate by Israeli standards. The highest frequency of infection was in the nought to nine-year-old group. High frequencies were also observed among 30- to 49-year-old women. The sanitary and hygienic conditions in the kibbutz, checked at the time of the epidemic and five years later, were extremely poor. These findings support the generally accepted idea of the close relationship between personal hygiene, sanitary food conditions and amoebic infection.

Adolescent↗
PubMed1984

Anti-Ia reactivity in sera from subjects with Entamoeba histolytica infection.

Sera from 15 patients with Entamoeba histolytica infection were tested for anti T-cell antibodies by assessing cross-reacting specificities with the antigens defined by an anti-Ia hybridoma antibody. T cells prepared by sheep erythrocyte rosetting were preincubated with the test sera and then with the anti-Ia antibody. Binding of the specific monoclonal antibody was assessed by rosetting with ox erythrocytes conjugated with goat anti-mouse IgG. Eight sera from amoebic patients were found to block the binding of monoclonal mouse hybridoma anti Ia-antibody to T cells. Blocking of anti-Ia binding was not due to Fc IgG receptor binding by immune complexes nor was it HLA-DR restricted. T cells pre-treatment with the amoebic sera positive for anti-Ia activity showed reduced activity when tested in the autologous mixed lymphocyte reaction (AMLR). The results of our study seem to suggest the existence of specific anomalies of immunoregulation during E. histolytica infection which may play a role in inducing immune disregulation in vivo.

Adult↗
PubMed1984

Influence of geographical factors in the distribution of pathogenic zymodemes of Entamoeba histolytica: identification of zymodeme XIV in India.

Stocks of Entamoeba histolytica isolated and maintained in a variety of culture media, both axenic and polyxenic, were compared with each other and with strains previously characterized. The present stocks were isolated from subjects living in various cities in India. Using the enzyme patterns of: E C 5319 glucose phosphate isomerase (GPI); E C 11140 L-malate: NADP+ oxidoreductase (oxaloacetate decarboxylating) (ME): E C 2751 phosphoglucomutase (PGM); and E C 2711 hexakinase (HK), developed after electrophoresis, three zymodemes were identified in 54 individual isolations of E. histolytica. Most importantly only one zymodeme associated with pathogenicity occurred, identified 28 times, among the collection, one of which was from a liver abscess.

Adult↗
PubMed1984

Attempts at oral infection of rats and mice with trophozoites of Entamoeba histolytica.

Groups of athymic rnu rats were found to be susceptible to SAW 408 Entamoeba histolytica introduced intra-intestinally. The same strain of rat could be infected orally with cultured trophozoites using a gastric secretion inhibitor, cimetidine, as a pretreatment. Groups of Lac:P and Wistar rats similarly treated were also found to be susceptible although the parasite population growth was slow. A similar regimen attempted on susceptible mice was unsuccessful.

Amebiasis↗
PubMed1985

Lethal recognition between Entamoeba histolytica and the host tissues.

Lethal recognition between Entamoeba histolytica and the tissues and defence systems of the host results in a continuous interplay that determines the development of pathological lesions: (i) we have identified several of the steps and mediators utilized by the trophozoites to destroy host cells by contact-mediated cytolysis; (ii) we have established that the alternative complement system represents the main defence available to the host against the invading parasite. The amoebae recognize target cells by means of a lectin specific for N-acetylgalactosamine-containing surface glycoproteins. This recognition appears to activate the amoeba to release, in the area of contact, an attack complex that induces the host cells to undergo cytolysis. The main component of the attack complex is thought to be amoebapore, an ion-channel forming protein that incorporates spontaneously into target cells leading to their depolarization by creating a pathway for ions to flow down their concentration gradient. The known properties of amoebapore are described. The acquisition of complement resistance by the invading trophozoites is essential for their survival within the host and therefore underlies virulence. The resistance to complement killing is not a permanent property of the amoebae. It is lost during axenization and reappears on passage through the host or when the trophozoites are grown axenically in the presence of active complement.

Acetylgalactosamine↗
PubMed1986

Immunodiagnosis of Entamoeba histolytica and Ascaris lumbricoides infections in Caucasian and aboriginal Australians.

The immunodiagnostic efficiency of an indirect immunofluorescence test (IFAT) and in vitro lymphocyte proliferative responsiveness (cell mediated immunity test, CMIT) used to measure the immunological responses of individuals with known natural Entamoeba histolytica and Ascaris lumbricoides infections, was studied under survey conditions. E. histolytica was common among Aborigines from Cherbourg, Kowanyama and Central Australia, but it was not found in Brisbane Caucasians. The protozoan was selected for the study because it was prevalent and purified antigen was commercially available. Immunodiagnosis for A. lumbricoides was made using an antigen prepared by affinity chromatography. Diagnosis based on frequency distribution of immunological data gave valid assessment of the number of infected individuals in each population studied.

Adolescent↗
PubMed1987

Enzyme linked protein-A: an ELISA for detection of amoebic antibody.

Enzyme linked protein-A was used to develop an enzyme linked immunosorbent assay (ELISA) system for the detection of circulating antibodies to amoebic antigen. The specificity of protein-A to bind IgG only through Fc receptors, makes the test more specific for the detection of IgG antibodies to amoebic antigen. The ELISA system was used to detect amoebic antibody in control subjects (56), patients with amoebic liver abscess (79) and Entamoeba histolytica cyst-passers (10) and the results compared with those of indirect haemagglutination assay (IHA). The ELISA was more sensitive and detected 74.7% of cases with amoebic antibody in amoebic liver abscess compared with 66.7% detected by IHA. The test was more specific, sensitive and easy to perform and is recommended as a test of choice for the serological diagnosis of amoebic liver abscess.

Antibodies↗
PubMed1987

Immunocytochemical detection of Entamoeba histolytica.

Human anti-Entamoeba histolytica immunoglobulin was used to detect Entamoeba histolytica in 74 positive samples from several different sources, using an indirect immunoperoxidase method. In 73 samples, the protozoan was easily identified. Trophozoites and cysts of all cultured Entamoeba strains examined were strongly stained, and as few as 3 trophozoites per microscope slide could be detected. In addition, 51 negative control samples were also tested and non-specific reactions were not observed. These preliminary results show that this method is both sensitive and specific, and can easily detect trophozoites and cysts of different E. histolytica strains.

Amebiasis↗
PubMed1988

The prevalence of Entamoeba histolytica in lactating women and in their infants in Bangladesh.

Entamoeba histolytica was studied in 33 lactating women and their infants in a periurban village in Bangladesh. Infant-mother pairs were followed for a period of 10-15 months: 67% of mothers excreted E. histolytica during the observation period, the majority for 3 months or more. Only one mother was symptomatic, with a mild, non-dysenteric diarrhoea. 58% of mothers were seropositive, several of them continuously and with a high titre, indicating past invasive infection. 67% had detectable antibodies in breast milk and 36% in saliva. Despite the high prevalence of E. histolytica in these mothers, infants were mostly uninfected: E. histolytica cysts in small numbers were found in only 2 of 1200 samples from infants aged 6 and 10 months. Several of the children were infected with Giardia lamblia. Although lower exposure to E. histolytica than to Giardia may account for the difference in infant infection rates with these parasites, defence mechanisms possibly exist which protect against E. histolytica but are ineffective against Giardia.

Adolescent↗
PubMedDate not supplied

Virulence of pathogenic and non-pathogenic zymodemes of Entamoeba histolytica (Indian strains) in guinea-pigs.

Guinea-pigs were inoculated with Entamoeba histolytica strains isolated from cases of amoebic liver abscess, amoebic dysentery and asymptomatic cyst passers and the strains were classified in zymodemes by isoenzyme electrophoresis. It was observed that certain non-pathogenic zymodemes were potentially pathogenic for the guinea-pigs. The relationship of zymodemes and virulence in laboratory animals is discussed.

Amebiasis↗
PubMedDate not supplied

Entamoeba histolytica infections in flight personnel of an international airline.

A cohort of 99 subjects, members of the flight staff of Lufthansa German airlines, all infected with Entamoeba histolytica, were followed over a period of 2.5 years to monitor their clinical and parasitological status. All but 4 of the subjects were infected with non-pathogenic zymodemes of E. histolytica and had negative amoebic serology, and most were clinically well. One male heterosexual carrying a pathogenic zymodeme was found, despite massive treatment regimes, to carry the infection persistently for 12 months. Most non-pathogenic infections were left untreated.

Aircraft↗