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PubMed1978

[Amebiasis--retrospective analysis of 453 cases in the Zürich region].

In a retrospective study 453 cases of amebiasis were analyzed with regard to duration, purpose, and location of the patients' stay abroad. Diarrhea and abdominal complaints were the predominating features of the history, but occasionally constipation was the only symptom. The patients usually had chronic intestinal amebiasis which was intermittently slightly dysenteric, rather than non-dysenteric as defined by the WHO. There were two cases each of ameboma and colonic stricture and three liver abscesses, one of which proved fatal after complicating peritonitis. Therapy with a tissue and a lumenal amebicide proved to be the most efficient combination, with a success rate exceeding 94% in the controlled cases.

Adolescent↗
PubMed1995

Evaluation of three serological tests for the detection of antiamebic antibodies applied to sera of patients from an area endemic for amebiasis.

Two enzyme immuno assays based on a single recombinant Entamoeba histolytica antigen (P1-EIA) or soluble E. histolytica extract (SA-EIA) as well as a latex agglutination test using an E. histolytica membrane fraction (M-LA) were evaluated for its use to detect anti-amebic serum antibodies in patients from Durban, South Africa, an area endemic for amebiasis. In a previous study, all three test systems were found to be reliable in terms of sensitivity and specificity when applied to sera of European individuals. By analysing a total of 167 serum samples of patients from the Durban area, suffering from invasive amebiasis (n = 76) or miscellaneous diseases unrelated to E. histolytica infection (n = 91), the present study revealed sensitivity for the detection of anti-amebic antibodies of 97.4% for SA-EIA, 86.8% for P1-EIA and 96.1% for M-LA, respectively. Specificity was high for P1-EIA (96.7%) and M-LA (92.3%) but substantially lower for SA-EIA (62.6%). In addition, antibody responses to the recombinant P1 antigen were analysed in 16 patients with amebic liver abscess before and after anti-amebic treatment. The results indicated that most of the patients lost their specific antibody response within 7 month of follow up. Therefore, P1-EIA seems to be a valuable test for distinguishing between present and past E. histolytica infections.

Amebiasis↗
PubMed1977

[Epidemiology of amebiasis and of tropical malaria].

The steady growth of intercontinental travel is causing an increasing incidence of tropical diseases in Switzerland. Malaria and amebiasis deserve special attention, due to their frequency and potential fatality. The epidemiology, clinical findings, diagnostic approach, and current treatment of malaria and amebiasis are briefly reviewed. If these infections are recognized in time and treated according to modern standards, fatal outcome is extremely rare.

Amebiasis↗
PubMed1997

Cerebral amebiasis in the acquired immunodeficiency syndrome.

Rare cases of cerebral amebiasis have been described in AIDS patients. We report the case of a 46 year-old homosexual man with AIDS who developed an intermittent amnesia and a right palpebral ptosis. The cerebrospinal fluid contained 169 cells (75% lymphocytes). The patient died five days after hospitalization. Necropsy revealed thrombosis of small vessels of the periventricular regions as well as necrosis and hemorrhage of the periventricular tissue, cerebellum and brainstem. The inflammatory process was scarce and composed mainly of CD-68 positive macrophages. In these regions as well as in meninges there were many trophozoites of ameba of the Acanthamoeba group. Although cerebral amebiasis is rare even in AIDS, the clinician should be attentive to this diagnosis in patients with an insidious encephalitis and cerebral cognitive abnormalities, with or without focal motor signs.

AIDS-Related Opportunistic Infections↗
PubMed1989

Nondysenteric intestinal amebiasis. Colonic morphology and search for Entamoeba histolytica adherence and invasion.

There is controversy regarding the presence of colonic mucosal abnormalities or mucosal invasion by Entamoeba histolytica in patients with "nondysenteric intestinal amebiasis." To determine the role of E. histolytica in causing symptoms and mucosal changes and to detect if mucosal invasion by E. histolytica is present in nondynsenteric intestinal amebiasis, we evaluated 24 E. histolytica-infected patients (stool microscopy positive for E. histolytica) and 12 noninfected controls who presented with chronic gastrointestinal symptoms, but without dysentery, to a clinic in Calcutta. The colonic mucosa was evaluated at colonoscopy, and mucosal biopsies obtained from the cecum, sigmoid colon, and rectum were evaluated by light microscopy, indirect immunofluorescence microscopy, and scanning electron microscopy. At colonoscopy mucosal ulcerations were absent in all the controls and all except one of the E. histolytica-infected patients. E. histolytica trophozoites or cysts were not seen in the lamina propria or on the luminal surface in any infected patient by light and immunofluorescence microscopy. On scanning electron microscopy, structures that resembled rounded E. histolytica trophozoites were seen on the luminal surface in two of 19 cecal specimens from the infected patients. Moderate or severe mucosal inflammation was frequent on light microscopy in both the E. histolytica-infected patients and the noninfected controls with the cecum involved in two thirds of both groups. Antibodies to E. histolytica were detected in serum of 25% of study patients and 58% of controls. Mucosal inflammation did not correlate with stool positivity for E. histolytica or seropositivity for ameba antibody.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1998

Host-pathogen interaction in amebiasis and progress in vaccine development.

Entamoeba histolytica, the causative organism of invasive intestinal and extraintestinal amebiasis, infects approximately 50 million people each year, causing an estimated 40 to 100 thousand deaths annually. Because amebae only infect humans and some higher non-human primates, an anti-amebic vaccine could theoretically eradicate the organism. Uncontrolled epidemiologic studies indicate that acquired immunity to amebic infection probably occurs and that such a vaccine might be feasible. Application of molecular biologic techniques has led to rapid progress towards understanding how Entamoeba histolytica causes disease, and to the identification of several amebic proteins associated with virulence. These proteins are now being evaluated as potential vaccine components. Parenteral and oral vaccine preparations containing recombinant amebic proteins have been effective in preventing disease in a gerbil model of amebic liver abscess. Although systemic and mucosal cellular and humoral immunity both appear to play a role in protection against Entamoeba histolytica, the relative importance of each in the human immune response remains unknown. No animal model of intestinal amebiasis currently exists, moreover, so it has been impossible to evaluate protection against colonization and colitis. Further investigation of the fundamental mechanisms by which Entamoeba histolytica causes disease and of the human immune response to amebic infection is necessary to assess the true feasibility of an anti-amebic vaccine.

Animals↗
PubMed2003

Endoscopic view of rectal amebiasis mimicking a carcinoma.

We report the case of a 45-year-old man with rectal amebiasis, presenting with rectal bleeding and chronic diarrhea, confirmed on rectal biopsy. The endoscopic view was highly suggestive of a carcinoma and caused confusion about its etiology. The striking difference in the endoscopic view before and after medical therapy of the tumor-like lesion was remarkable. This case illustrates the importance of an accurate histologic diagnosis before definitive treatment and highlights the mimicry of rectal carcinoma by rectal amebiasis on endoscopy.

Dysentery, Amebic↗
PubMed1999

Amebiasis: Clinical Implications of the Recognition of Entamoeba dispar.

Entamoeba histolytica was recently reclassified to recognize the existence of two genetically distinct but morphologically indistinguishable species: E. histolytica, the protozoan parasite that causes amebic dysentery and liver abscess, and Entamoeba dispar, a nonpathogenic intestinal parasite. Acceptance of this redefinition has dramatically changed both our understanding of the true epidemiology of E. histolytica and the optimal methods for diagnosing amebiasis. Molecular-based diagnostic tests using polymerase chain reaction (PCR) to amplify amebic DNA or enzyme-linked immunosorbent assay (ELISA) to identify amebic antigens in stool samples have been developed to distinguish infection with E. histolytica from infection with E. dispar. Because of its ability to differentiate strains of E. histolytica, PCR is a very useful research tool. Only the ELISA-based test is simple to perform, making it clinically useful in the developing world. To avoid unnecessary treatment of individuals infected with E. dispar, the World Health Organization has stressed the importance of making a specific diagnosis of E. histolytica infection (not E. histolytica/E. dispar) before treating for amebiasis.

Journal Article↗
PubMed2006

The current status of an amebiasis vaccine.

Efficient control of infectious diseases requires the development and application of suitable vaccines. Development of vaccines against amebiasis is still in its infancy. However, in recent years progress has been made in the identification of possible vaccine candidates, the route of application and the understanding of the immune response that is required for protection against amebiasis.

Administration, Oral↗
PubMed1975

Multiple cerebral abscesses complicating hepatopulmonary amebiasis.

A 3-year-old boy with hepatopulmonary amebiasis treated with chloroquine phosphate for 20 days subsequently was found to have three brain abscesses and responded to prolonged combined therapy with metronidazole and chloroquine phosphate. Cerebral amebiasis should be considered in any patient with amebic dysentery, hepatic abscess, or pulmonary involvement in whom signs or symptoms of central nervous system involvement appear. A prolonged course of appropriate therapy with periodic brain scanning for evidence of improvement is suggested.

Brain Abscess↗
PubMed2001

Amebiasis.

Human amebiasis is caused by the protozoan parasite Entamoeba histolytica. Invasion of the colonic mucosa by the trophozoite form of this parasite generally results in the clinical syndrome of amebic dysentery, although there is a wide range of clinical presentations. Some patients will progress to disseminated disease, with resulting amebic liver abscesses. Although it is estimated that 10% of the world's population is infected with E. histolytica, only 1% of these patients will manifest disease. The diagnosis is usually made by microscopically identifying the microorganism in a stool specimen. The antibiotic of choice for treatment of amebiasis is metronidazole, 750 mg, three times daily for 10 days.

Journal Article↗
PubMed1982

An outbreak of amebiasis spread by colonic irrigation at a chiropractic clinic.

From June 1978 through December 1980, at least 36 cases of amebiasis occurred in persons who had had colonic-irrigation therapy at a chiropractic clinic in western Colorado. Of 10 persons who required colectomy, six did. Of 176 persons who had been to the clinic in the last four months of 1980, 80 had received other forms of treatment. Twenty-one per cent of the colonic-irrigation group had bloody diarrhea, as compared with 1 per cent of the non-irrigation group (P = 0.00013). Thirty-seven per cent of the colonic-irrigation group who submitted specimens had evidence of amebic infection on either stool examination or serum titer, as compared with 2.4 per cent in the non-irrigation group (P = 0.00012). Persons who were given colonic irrigation immediately after a person with bloody diarrhea received it were at the highest risk for the development of amebiasis. Tests of the colonic-irrigation machine after routine cleaning showed heavy contamination with fecal coliform bacteria. The severity of disease in this outbreak may have been related to the route of inoculation.

Adult↗
PubMed2001

Amebiasis and mucosal IgA antibody against the Entamoeba histolytica adherence lectin in Bangladeshi children.

Amebiasis is the third leading parasitic cause of death worldwide, and it is not known whether immunity is acquired from a previous infection. An investigation was done to determine whether protection from intestinal infection correlated with mucosal or systemic antibody responses to the Entamoeba histolytica GalNAc adherence lectin. E. histolytica colonization was present in 0% (0/64) of children with and 13.4% (33/246) of children without stool IgA anti-GalNAc lectin antibodies (P= .001). Children with stool IgA lectin-specific antibodies at the beginning of the study had 64% fewer new E. histolytica infections by 5 months (3/42 IgA(+) vs. 47/227 IgA(-); P= .03). A stool antilectin IgA response was detected near the time of resolution of infection in 67% (12/18) of closely monitored new infections. It was concluded that a mucosal IgA antilectin antibody response is associated with immune protection against E. histolytica colonization. The demonstration of naturally acquired immunity offers hope for a vaccine to prevent amebiasis.

Animals↗
PubMed1995

New concepts regarding the pathogenesis of amebiasis.

Our understanding of the pathogenesis of amebiasis has progressed significantly since Dr. Braude's description of the major clinical syndromes of amebic liver abscess. His hypothesis that invasive amebic strains must be resistant to complement-mediated lysis has been confirmed. We have also shown that Entamoeba histolytica activates complement by a unique mechanism, i.e., cleavage of C3 by an extracellular cysteine proteinase. Cysteine proteinases are important virulence factors encoded by at least three genes; one gene, acp1, is unique to invasive strains. The amebic cysteine proteinases are homologous to proteinases released by transformed cells and may represent a common mechanism of tissue invasion. The initial division of Entamoeba into invasive E. histolytica and noninvasive Entamoeba dispar by isoenzymes has been supported by genetic differences between amebae. Thus, a model of pathogenesis differentiating between two separate species of Entamoeba best explains the epidemiology, clinical syndromes, and pathology of amebiasis.

Animals↗
PubMed2006

Human immunodeficiency virus infection and amebiasis.

Pediatric human immunodeficiency virus (HIV) infection is a major and increasing burden worldwide, but particularly in sub-Saharan Africa. Coinfection with other pathogens increases the likelihood of progression of HIV/acquired immunodeficiency syndrome (AIDS), and the immunosuppressive consequences of the disease predispose to opportunistic infections that can run a fulminant course. Despite high prevalence, amebiasis has not appeared as a major source of morbidity during the HIV/AIDS pandemic. Information from recent sources, however, appears to suggest that amebiasis may indeed be a risk for individuals living with HIV/AIDS.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Cutaneous amebiasis in a child and review of the literature.

Cutaneous amebiasis is a rare manifestation of infection with the parasite Entamoeba histolytica. We describe this infestation in a 9-year-old Mexican immigrant who presented with diarrhea and perianal ulcers. To our knowledge, this is only the tenth child with cutaneous amebiasis reported in the literature, and only the second from the United States. We review previous reports and emphasize the importance of a high index of clinical suspicion for early diagnosis and treatment to prevent potentially serious morbidity and even mortality.

Anal Canal↗
PubMedDate not supplied

Experimental amebiasis: immunohistochemical study of immune cell populations.

Distribution of immune cell populations was studied in a C3H/HeJ mouse model of intestinal amebiasis from 5 to 60 days post-inoculation with Entamoeba histolytica, using immunoperoxidase techniques. At various time intervals, the ceca from mice were fixed in 10% formalin, dehydrated, embedded and sectioned at 5 microm. Sections were incubated with conjugated peroxidase-labelled antibodies to mouse IgA, IgM, and IgG. Color was developed with 3, 3'-diaminobenzidine tetrahydrochloride (DAB)/H2O2 solution. CD3, CD4, and CD8 cells, as well as neutrophils were detected by reacting with biotin-conjugated anti-mouse CD3, CD4, CD8, and CD11 monoclonal antibodies, followed by their incubation with avidin-peroxidase and color development with DAB/H2O2 solution. Erythrocin B and toluidine blue were used to stain eosinophils and Mast cells, respectively. It was observed that the IgA+ plasma cell was the dominating immune cell present in the mucosa, although eosinophils, neutrophils, CD3+, CD4+, CD8+, IgM+, IgG+ cells and Mast cells were also seen. Results of this study suggest that infiltration of immune cells at the mucosal surface during intestinal amebiasis might be important in the defense against this parasite.

Animals↗
PubMed1997

Progress towards development of a vaccine for amebiasis.

The application of molecular biologic techniques over the past decade has seen a tremendous growth in our knowledge of the biology of Entamoeba histolytica, the causative agent of amebic dysentery and amebic liver abscess. This approach has also led to the identification and structural characterization of three amebic antigens, the serine-rich Entamoeba histolytica protein (SREHP), the 170-kDa subunit of the Gal/GalNAc binding lectin, and the 29-kDa cysteine-rich protein, which all show promise as recombinant antigen-based vaccines to prevent amebiasis. In recent studies, an immunogenic dodecapeptide derived from the SREHP molecule has been genetically fused to the B subunit of cholera toxin, to create a recombinant protein capable of inducing both antiamebic and anti-cholera toxin antibodies when administered by the oral route. Continued progress in this area will bring us closer to the goal of a cost-effective oral combination "enteric pathogen" vaccine, capable of inducing protective mucosal immune responses to several clinically important enteric diseases, including amebiasis.

Administration, Oral↗