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PubMed1983

Secondary cerebral amebiasis.

Four cases of E. histolytica infection of the brain among 80 cases of hepatic amebiasis collected over a period of 18 years are reported. The patients were males aged 2, 30, 40 and 50 years. Three cases presented with chest and neurological manifestations. Intestinal and hepatic lesions were present in all and lung lesions in three cases. The cases with neurological manifestations showed extensive, almost confluent lesions in the brain. It is proposed that the condition should be called "Secondary cerebral amebiasis".

Adult↗
PubMed1991

Laboratory diagnosis of amebiasis.

The procedure used to diagnose amebiasis varies depending on the geographic location of the laboratory. However, in general, the microscopic diagnosis and differentiation of E. histolytica from other intestinal amebae is most satisfactorily achieved when the specimen is preserved immediately and both a concentration and stained smear are examined. The number of additional positive findings achieved by the cultivation of fecal material does not justify the time and cost involved. On the other hand, serology is a useful adjunct to diagnosis, especially in patients with extraintestinal amebiasis. The commercial development of antigen detection kits and DNA probes may provide more rapid, accurate, and less costly diagnostic procedures for the future. New guidelines need to be formulated regarding the number of specimens to be submitted, and the cost effectiveness of various diagnostic procedures should be evaluated.

Animals↗
PubMed2000

Ultrastructure of the Endolimax nana cyst.

This is the first report on the ultrastructure of the Endolimax nana cyst. These cysts are mostly ovoid in shape and have a distinct cyst wall measuring 80 nm. The nuclear membrane is without pores or associated chromatin deposits. The cytoplasm does not have mitochondria or a Golgi apparatus but shows elongated tubular structures made up of a double row of ribosome-like particles. The nature and function of this structure is not known, but it appears to be characteristic of this species and has not been reported from any other intestinal ameba.

Amebiasis↗
PubMed1992

Growth inhibition of Entamoeba histolytica by rat colon components.

Susceptibility to invasive amebiasis has been suggested to be due to intrinsic amebic factors and/or to such host factors as intestinal microflora, mucus and colonic redox potential. We investigated the effect of rat colon components on the growth of axenically cultured E. histolytica trophozoites. Extracts of rat colon tissue produced a 57% amebic growth inhibition. The main growth inhibitory components were precipitated by 65% ammonium sulfate and were heat-sensitive. These components were partially separated by ultrafiltration and gel filtration chromatography. Thus, we found colonic components (Mr 50-100 kDa) that produced strong growth inhibition (75%). These results suggest that rat colonic products may play an active role in resistance to amebic infection.

Animals↗
PubMedDate not supplied

[Intestinal parasitism in eastern Gabon].

A survey of 1,548 stools samples carried out in Gabon showed in the adult population a parasitism ratio of about 100%. Among the protozoa, D. fragilis was found in 0.3% of the cases. In contradiction with the usual observations in tropical Africa, A. lumbricoides and T. trichiura infestation is very high in the villages. The demonstration of S. intercalatum in almost every place of the survey and an important focus at Okondja proves the extension of this bilharziosis.

Adult↗
PubMed1981

Prevalence of intestinal helminths and protozoans in a rural population segment of the Dominican Republic.

There are few reports of parasitic disease prevalence in the Dominican Republic. The most recent study was that by Mackie et al. (1951). Examination of purged specimens from individuals employed by two sugar plantations demonstrated generally high prevalences of a number of helminths and protozoans. We report here the findings of a prevalence study using a population sample of 453 individuals. Ascaris lumbricoides, Trichuris trichiura, hookworm, Enterobius vermicularis, Giardia lamblia and Entamoeba coli were found.

Adolescent↗
PubMedDate not supplied

Risk of cancer onset in sub-Saharan Africans affected with chronic gastrointestinal parasitic diseases.

Gastrointestinal Schistosomiasis and Amebiasis are uncommon in the western world, while such infections are frequent in the African community. In addition to the problems associated with the clinical symptoms of these parasitic infections, it is important to stress the increase in cancer of the Gastro-Intestinal (GI) tract. In this study we evaluate the prevalence of cancer in patients affected by chronic inflammatory diseases caused by the above named parasites. In three years, from January 2000 to December 2003, we observed a total of 1199 subject. Of these, 950 presented with complaints of diarrhoea, vomiting, abdominal pain, melena, hematemesis, rectal discharges and alteration of bowel habits. A total of 818 patients were evaluated in Uganda (Mulago and Arua hospitals) and 381 at Luisa Guidotti Hospital in Zimbabwe. An exhaustive clinical history was collected for each patient and then physical and laboratory examinations were performed. The clinical files of all patients previously admitted to the respective hospitals were obtained and the information taken from these files was then integrated with our clinical findings. Subjects who were found free of gastro-intestinal disease after examinations and did not have a clinical history of infective GI disease but presented with other pathologies, were regarded as control group. The control group was composed of 249 subjects. The subjects who were positive on examination underwent further investigations. The number of patients affected by schistosomiasis and amebiasis were 221 and 224 respectively. The number of patients who suffered from aspecific enterocolitis was 454, intestinal tuberculosis was present in 21 patients and we found 30 patients with esophageal candidiasis. Patients who had the above mentioned GI diseases were then divided into 3 groups. First group was composed of patients who had a clinical history of infective GI diseases and were re-admitted for similar symptoms, and on examination were positive for the presence of the same infective GI diseases. Such patients were placed in the Chronic group. The second group was formed of patients who had previously undergone treatment for infective GI diseases but on readmission were found free of infective GI disease, and this group was described as the Cured group. They had symptoms associated with other pathologies. A third group, which we described as the Acute group was composed of patients who did not have any previous case of GI infection and were admitted for the first time. Such patients were found positive on examination for infective GI diseases. In the 950 patients, we found a total of 45 tumors. The tumors were prevalent (42 tumors) in the chronic group. In 34 patients the tumor was in the colo-rectal region, in 3 patients in the stomach, in 4 patients in the esophagus and 1 patient had cancer in the small bowel. Our results show a strong association between the chronic infection of the GI tract and the likelihood to develop tumors. However, it is not clear which biological mechanisms are implicated in such transformations. They may depend on the chronic inflammation of the GI mucous which permits the entrance of carcinogenic materials or on the effects of mutagenic products produced by the parasites or both.

Africa South of the Sahara↗
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↗
PubMedDate not supplied

Immunologic tools in the diagnosis of amebiasis: epidemiology in the United States.

Several immunodiagnostic tests that detect antibody to Entamoeba histolytica are now available. Such tests are useful when demonstration of the etiologic agent is difficult (as in liver abscess), when routine diagnostic tests fail to disclose the organisms (as in severe intestinal disease compromised by failure of the laboratory to identify the organism or by the patient's use of interfering substances), and as epidemiologic tools for determining the prevalence of invasive disease in populations. Knowledge of the prevalence of amebiasis in the United States is incomplete because the disease is not routinely reported. Information currently available on the prevalence of amebiasis has accumulated from studies of selected groups that include children, institutionalized persons, members of extended families, immigrants, and male homosexuals.

Amebiasis↗
PubMed2000

Entamoeba histolytica cysteine proteinases with interleukin-1 beta converting enzyme (ICE) activity cause intestinal inflammation and tissue damage in amoebiasis.

The protozoan parasite Entamoeba histolytica causes intestinal inflammation and ulceration. Amoebic trophozoites activate the transcription factor NF-kappa B in human intestinal epithelial cells, initiating an inflammatory response programme with resultant damage to the intestinal tissue. Amoebic cysteine proteinases have been proposed as important virulence factors for amoebiasis. To test the role of amoebic cysteine proteinases in the pathogenesis of amoebic colitis, human intestinal xenografts in SCID mice were infected with E. histolytica trophozoites expressing an antisense message to ehcp5. The cysteine proteinase-deficient amoeba failed to induce intestinal epithelial cell production of the inflammatory cytokines interleukin (IL)-1B and IL-8, and caused significantly less gut inflammation and damage to the intestinal permeability barrier. The critical role of amoebic cysteine proteinases in human gut inflammation and tissue damage may be explained by our discovery that amoebic cysteine proteinases possess IL-1B converting enzyme (ICE) activity. This ICE activity could contribute to intestinal inflammation by activating human pIL-1B released by damaged intestinal cells. These results demonstrate for the first time that amoebic cysteine proteinases are a key virulence factor in amoebic colitis, and provide a novel mechanism for their activity.

Amebiasis↗
PubMed1986

Entamoeba histolytica: effect of growth conditions and bacterial associates on isoenzyme patterns and virulence.

In xenic culture, isolates of Entamoeba histolytica from asymptomatic carriers are characterized, with rare exception, by possession of a nonpathogenic zymodeme. During the process of axenizing such an isolate, strain CDC:0784:4, a change in the pattern of the isoenzymes from nonpathogenic zymodeme I to pathogenic zymodeme II was observed 40 days after the amebae had been transferred from a medium for xenic cultivation to one used for axenic cultivation, but before axenization of the amebae had actually occurred. Axenization was accomplished by feeding the amebae lethally irradiated bacteria while suppressing and finally eradicating with antibiotics the bacterial flora accompanying the amebae in the original xenic culture. The change in zymodeme was accompanied by a change in virulence as evidenced by the ability of the amebae to produce hepatic abscesses in hamsters and to destroy monolayers of tissue culture cells. Two explanations are offered for the observed changes in zymodeme and virulence: a zymodeme is not a stable inherent property of the ameba. Alternatively, the original isolate consisted of two zymodeme populations and the conditions of growth selected for one or the other of the populations. In either case, our results suggest that the finding of a particular zymodeme in a culture of E. histolytica isolated from an asymptomatic carrier of the parasite cannot be used to predict a clinical condition or serve as a basis for the recommendation of therapy.

Amebiasis↗