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PubMed1980

A seroepidemiological study of amebiasis in Surinam by the enzyme-linked immunosorbent assay (ELISA).

Sera from nine populations in Surinam, South America, were screened for antibodies against Entamoeba histolytica by the enzyme-linked immunosorbent assay (ELISA) technique and a precipitin test (gel diffusion or counterimmunoelectrophoresis). In two small surveys in 1974 and 1978, a high rate of clinically significant ELISA titers was found in a rather isolated group of Amerindians living near the Brazilian border, predominately in the youngest age groups. Amerindians living near the coast showed a low level of seropositivity. Low levels were also found in Bush Negro villages in the interior of Surinam and in Hindustani school children from the savannah area. A high frequency of ELISA titers greater than or equal to 320, indicating a high rate of invasive amebiasis, was detected in persons in a mental institution in Paramaribo. It is concluded that the ELISA, which is much more sensitive than the precipitin tests, is a useful screening test for assessing the prevalence of invasive amebiasis on an epidemiological scale.

Amebiasis↗
PubMed1985

Intestinal invasive amebiasis: an experimental model in rodents using axenic or monoxenic strains of Entamoeba histolytica.

A new experimental model for the production of early stages of invasive intestinal amebiasis in hamsters or guinea pigs with axenic or monoxenic cultures of Entamoeba histolytica of the HM1:IMSS strain is reported. The model is called the washed-closed cecal loop, because it involves the washing out of the cecum contents of conventionally raised animals and the formation of a closed loop, into which amebas are inoculated. Colonization occurred in all inoculated animals. After 48 hr, macroscopic ulcerations of the cecal mucosa were found in approximately one-half (5/12) of the animals inoculated with axenic amebas and in more than two-thirds (10/12) of those inoculated with monoxenic parasites. The amebic nature of the mucosal ulcerations was confirmed by light and transmission electron microscopy, as well as by scanning electron microscopy (SEM) of fractured samples of cecal mucosa. SEM provided a rapid and reliable technique to assess both the extent and the nature of the lesions. This model is particularly useful for the study of the pathogenesis of early intestinal lesions produced by virulent amebas, and may also be applied to experimental studies on the immunology of invasive intestinal amebiasis.

Amebiasis↗
PubMed1986

Cutaneous amebiasis of the face: a case report.

This paper describes a case of cutaneous amebiasis of the face in a 17-month-old girl. About four weeks prior to admission she had diarrhea with high suspicion of intestinal amebiasis. Fifteen days later she presented with edema of the right lower eyelid and epiphora. There was a vesicle in the inner angle of the eye which spontaneously drained, causing loss of the underlying tissue. The ulcer developed rapidly, destroying periorbital tissue. Both cytology and biopsy of the ulceration border showed abundant trophozoites of Entamoeba histolytica. Treatment was specific therapy and surgery.

Amebiasis↗
PubMed2002

Epidemiology of amebiasis in a region of high incidence of amebic liver abscess in central Vietnam.

The recent identification of Entamoeba dispar as a separate species, which is nonpathogenic for humans but morphologically indistinguishable from Entamoeba histolytica, has prompted the World Health Organization to recommend reinforced efforts for reassessment of the epidemiology of amebiasis and, in particular, of E. histolytica. In this regard, the distribution of amebic liver abscess (ALA) cases were analyzed in the province of Thua Thien Hué (TT Hué) in central Vietnam, a region known for its high incidence of invasive amebiasis. In addition, in a particular area of Hué City, a parasitologic and seroepidemiologic survey was performed to identify possible risk factors for transmission of E. histolytica. Based on the analysis of hospital charts from April 1990 to April 1998, 2,031 cases of ALA were identified, indicating an ALA incidence of at least 21 per 100,000 inhabitants per year. Incidence varied substantially between the various districts of TT Hué and directly correlated with population density. The risk for ALA was significantly higher in summer and was age and sex dependent because 95% of the cases were adults, of which more than 80% were males. There was no clustering of cases within households and recurrent cases of ALA occured more frequently than predicted in the study population. Despite the higher incidence of ALA in males, the parasitologic and seroepidemiologic survey revealed a significant higher infection rate for intestinal protozoon parasites, including E. histolytica in females. Besides level of education and access to a toilet or tapwater, use of river water was identified as an important risk factor for E. histolytica infection.

Amebiasis↗
PubMed2005

[Utility and limitations of laboratory diagnosis of amebiasis].

Entamoeba histolytica is an invasive and pathogenic protozoan parasite that causes amebiasis. It must be distinguished from Entamoeba dispar, a nonpathogenic commensal parasite of the human gut lumen that is morphologically identical to Entamoeba histolytica. Diagnosis of amoebic colitis currently requires combination of microscopic examination of stool specimens with another technique allowing positive identification of the two species. Stool culture followed by zymodem analysis is considered as gold standard but is not applicable in routine practice. Detection of specific Entamoeba histolytica antigens in stools is a fast, sensitive technique that should be considered as the method of choice. Stool PCR is a highly sensitive and specific technique but high cost make it unsuitable for use in endemic areas where economic conditions are difficult. The utility of serologic tests in distinguishing Entamoeba dispar from Entamoeba histolytica is controversial. However serology is still considered as the method of choice for diagnosis of extraintestinal amebiasis. Circulating Gal/GalNac lectin antigens can be detected in the serum of 96% of patients with untreated amoebic liver abscess. In the future this method should allow early diagnosis and treatment of extraintestinal amoebiasis in patients who have not yet developed detectable serum antibodies.

Amebiasis↗
PubMed2005

A rare cause of colonic stricture: amebiasis.

A 41-year-old man presenting with lower abdominal pain, constipation, abdominal distention, fever (37.5 degrees C) and fatigue was evaluated, and a mass localized to the left lower abdomen was identified. Radiographic and colonoscopic examination revealed a stricture 10 cm in length localized to the sigmoid-descending colon junction. The diagnosis of amebiasis was confirmed by histological examination of a biopsy specimen taken from the stricture and stool examination. One month after the initiation of metronidazole treatment, complete clinical and laboratory improvement was observed. In the differential diagnosis of colonic stricture, amebiasis should also be considered.

Adult↗
PubMed1975

Serological study of amebiasis and toxoplasmosis in the Lindu Valley, Central Sulawesi, Indonesia.

Results of a serology survey in April 1972 for Entamoeba histolytica and Toxoplasma gondii antibodies among 484 inhabitants of the isolated Lake Lindu Valley of Central Sulawesi (Celebes) are presented. Indirect hemagglutination antibody titers for amebiasis were found in over 10% of the population, although only 3.7% demonstrated significant titers of 1:128 or greater. There appeared to be no relationship between antibody titers and the age and sex of individuals tested, and the frequency distribution of antibody titers indicates a low prevalence of invasive amebiasis in the population. Indirect hemagglutination antibody titers for Toxoplasma gondii equal to or greater than 1:32 were found in 27.1% of the total population, and it appeared that the prevalence of titers increased with age in both sexes. More families with cats had Toxoplasma gondii antibody titers than families without cats.

Adolescent↗
PubMed1990

[Urinary amebiasis: a parasitosis of exceptional presentation].

We report a case of urinary tract amebiasis localized to the bladder. We reviewed the different ways secondary infection can spread to the urinary tract (rupture of hepatic amebic abscess, perforation in amebic dysentery, or hematogenous spread of amebas) and the primary form of presentation and spread that have been recently focussed upon, i.e. via the "ascending route" in deviant sexual habits of bisexuals and homosexuals, parasites in the anorectal area can colonize the urethra. We discuss the different diagnostic methods and treatment of urinary and intestinal amebiasis, as well as their possible relationship.

Amebiasis↗
PubMedDate not supplied

[Amebiasis. Surgical treatment in 1989].

Even when the number of patients with invasive amebiasis has decreased, the internist and surgeon must be alert in case that the patient requires an operation. Amebic liver abscess is treated medically; percutaneous evacuation is rarely used and surgical drainage is made when there is not response to medical treatment or there is high risk of abscess rupture. Operation is mandatory when the abscess has ruptured to the abdominal cavity or through the pericardial sac. In fulminant colitis it is necessary to resect the diseased portion of the colon without primary anastomoses. Amebic apendicitis is difficult to diagnosis before an operation. It may be suspected in cases of apendicitis if the cecal wall is inflammed. Colon ameboma requires medical treatment except if it is associated with necrosis or perforation. In a four year period (1985-1988) 294 patients with diagnosis of invasive amebiasis were admitted to three hospitals of the Instituto Mexicano del Seguro Social in Mexico City. 218 had hepatic abscess, 45 required surgical drainage with four deaths (9%) and four not operated patients died. In this series only four patients had their abscess drained percutaneously. 31 patients with amebic colitis were treated; three required colonic resection with one death. Ameboma was seen in five patients and there were 11 cases of amebic apendicitis. No deaths occurred in these last two groups.

Adolescent↗
PubMed1988

Inflammatory reaction in experimental hepatic amebiasis. An ultrastructural study.

One of the hallmarks of tissue necrosis produced by the human protozoan parasite Entamoeba histolytica, the causative agent of human amebiasis, appeared to be the lack of inflammatory reaction to the invading trophozoites. Recent evidence suggests, however, that inflammatory cells do appear during early stages of amebic destructive lesions and that they contribute to the establishment of foci of tissue necrosis in intestinal and liver lesions. The present analysis of the fine-structural changes that take place during early stages of amebic liver abscesses induced in hamsters after the intraportal inoculation of axenic amebas has shown that large numbers of polymorphonuclear leukocytes (PMNs) are recruited around invading amebas. These leukocytes lyse as a consequence of contact-mediated damage induced by the trophozoites. Amebas were also capable of ingesting apparently intact PMNs. Macrophages and eosinophils were also recruited at the foci of inflammation. At all times examined, trophozoites of Entamoeba histolytica survived in spite of being in close contact with PMNs or degranulating eosinophils. The ultrastructural observations have also shown the lack of direct contact between amebas and liver parenchymal cells during the initial stages of the focal liver necrosis induced by the parasite, therefore supporting the view that hepatic damage may be effected indirectly through lysis of inflammatory cells. The results also provide a basis for the understanding of the induction of experimental protective immunity against invasive amebiasis, a process which seems to be mostly dependent on cellular mechanisms.

Amebiasis↗
PubMed1985

The pathology of experimentally induced cecal amebiasis in gerbils (Meriones unguiculatus). Liver changes and amebic liver abscess formation.

The pathogenesis of experimentally induced cecal amebiasis in gerbils (Meriones unguiculatus) was studied from 5 to 60 days after inoculation. Ulcerative lesions were noted 10 to 60 days after inoculation. The sequential development of lesions was asynchronous and progressed from destruction of the interglandular epithelium and of glandular crypt elements to loss of mucosa and formation of granulomatous lesions in the submucosa involving the muscularis mucosae. Pathologic changes in the liver correlated with the formation of ulcerative cecal lesions. Subacute hepatic changes showed lymphocytic portal infiltrate, Kupffer cell hyperplasia, multinucleated giant cells, granuloma formation, and sinusoidal mononuclear and granulocytic infiltrates. Metastatic amebic liver abscesses occurred as early as 10 days after inoculation, and small abscesses were found in the portal areas of the right liver lobe. The sequential development and pathologic manifestation of the infection and the usefulness of the gerbil for the study of human intestinal amebiasis are discussed.

Amebiasis↗
PubMed1982

[Pleuropulmonary manifestations in amebiasis. Sixty-one cases seen in Abidjan over a three-year period (author's transl)].

Sixty-one observations of pleuropulmonary amebiasis are reported with a detailed analysis of radioclinical features In 13.1% of the cases there were no clinical signs of associated hepatic involvement. Diagnostic difficulties were encountered in 42.6% of the cases which were suggestive of bacterial pleuropulmonary disease, tuberculosis or carcinoma. Serologic tests for amebiasis, which were positive in 95% of the cases, are very helpful diagnostic tools. Metronidazole and its derivatives were used in 80% of the cases with satisfactory results: death occurred in 3.5% of the cases and good short-term results in 84.6%. Sequelae were mainly observed after amebic empyema which resulted in chronic pleural disorders in 27.7% of the cases.

Amebiasis↗
PubMed1982

[Amebiasis].

Infections with Entamoeba histolytica do not necessarily cause disease in those infected. The parasite may act as commensal (cysts living in the bowel) or it may cause a broad spectrum of clinical illness. Some of the factors causing overt disease are poorly understood. An acute amebic dysentery is accompanied by bloody stools, abdominal pain and indigestion. The most important extraintestinal complication of an amebic infection is a liver abscess causing severe pain, fever, nausea and vomiting. The diagnosis of an amebic infection is based upon isolation of the parasite from the stools. Extraintestinal amebiasis is diagnosed - apart from the clinical picture - by serology. For treatment of intestinal amebiasis so-called contact-amebicides can be recommended. An amebic abscess of the liver usually responds well to dehydroemetine, metronidazole or any other derivative or imidazole and chloroquine. Surgical treatment of amebic liver abscess is only required if complications arise.

Amebiasis↗
PubMedDate not supplied

Amebiasis: host-pathogen biology.

Invasive amebiasis caused by Entamoeba histolytica, and particularly amebic liver abscess, is a major public health problem in Mexico and some other countries because of the high incidence and mortality of this disease. This paper first discusses the pathogenic effect of E. histolytica and the defensive response of the host and then reports studies concerning the experimental induction of protective immunity to amebic infection. The pathogenic effect of E. histolytica is probably initiated by a lectin-mediated adhesion of trophozoites to target cells; the adhesion is followed by cytopathic activity and phagocytosis by the ameba. The defensive response is characterized by humoral and cellular immune reactions. Humoral immunity manifests itself by specific circulating antibodies useful in the diagnosis and seroepidemiology of amebiasis. Cellular immunity is shown by several characteristic reactions. Experimental induction of immunoprophylaxis with E. histolytica antigens represents the first stage in the development of a vaccine against E. histolytica for use in humans.

Adolescent↗
PubMed1983

Hepatic and gastric amebiasis in black and white colobus monkeys.

Three cases of hepatic amebiasis and one case of gastric amebiasis were diagnosed in black and white colobus monkeys during a 9-month period. The diagnosis was difficult because of the absence of trophozoites and cysts in the feces and because of few trophozoites found in many of the hepatic lesions. Indirect hemagglutination titers were diagnostic in 2 monkeys.

Amebiasis↗
PubMed1984

[A case of a single pleural localization of amebiasis].

The diagnostic of isolated pleural amebiasis is exceptional even in endemic countries. The reported observation illustrates this eventuality. The relation of this clinical factor leads to a general review on the pleuro-pulmonary manifestations of amebiasis, their mechanism and their treatment.

Adolescent↗
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↗