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PubMed1985

Amebiasis presenting as rectal bleeding without diarrhea in childhood.

A 6-year-old boy with no history of foreign travel had presented with rectal bleeding without diarrhea for 2 months. Despite negative stool cultures, a diagnosis of intestinal amebiasis was made by colonoscopy with tissue biopsy. In cases of persistent rectal bleeding, even without diarrhea, a diagnosis of amebiasis should be considered. When routine stool parasite examinations are negative, unsuspected amebiasis may be diagnosed by sigmoidoscopy or colonoscopy with tissue biopsy.

Biopsy↗
PubMed1998

Hepatic amebiasis among patients in a public teaching hospital.

The increase in immigration to the United States is associated with diseases, such as amebiasis, that are endemic to developing countries. We retrospectively reviewed 49 public-hospital patients with hepatic amebiasis occurring between 1985 and 1995. Most patients were immigrants (47) from Latin America (43), male (43), and young (mean age, 39.8 years). Symptoms noted by more than half were abdominal pain and fever. Ultrasonography showed single lesions in 70% and right-sided involvement in 85%. Serologies against Entamoeba histolytica were noted in 86%. After treatment, the median interval from admission to defervescence was 2 days, to normalization of white cell count 3 days, and to resolution of abdominal pain 4 days. Morbidity (one case of pericarditis) and mortality (one death in a cirrhotic man) were low. Hepatic amebiasis continues to be diagnosed in the United States, primarily among Hispanic and Asian immigrants. When appropriately considered, current diagnostic and therapeutic modalities result in rapid improvement and excellent outcome.

Adolescent↗
PubMed2006

Entamoeba histolytica infection in children and protection from subsequent amebiasis.

The contribution of amebiasis to the burden of diarrheal disease in children and the degree to which immunity is acquired from natural infection were assessed in a 4-year prospective observational study of 289 preschool children in an urban slum in Dhaka, Bangladesh. Entamoeba histolytica infection was detected at least once in 80%, and repeat infection in 53%, of the children who completed 4 years of observation. Annually there were 0.09 episodes/child of E. histolytica-associated diarrhea and 0.03 episodes/child of E. histolytica-associated dysentery. Fecal immunoglobulin A (IgA) anti-parasite Gal/GalNAc lectin carbohydrate recognition domain (anti-CRD) was detected in 91% (183/202) of the children at least once and was associated with a lower incidence of infection and disease. We concluded that amebiasis was a substantial burden on the overall health of the cohort children. Protection from amebiasis was associated with a stool anti-CRD IgA response. The challenge of producing an effective vaccine will be to improve upon naturally acquired immunity, which does not provide absolute protection from reinfection.

Animals↗
PubMed1992

Use of a recombinant 170-kilodalton surface antigen of Entamoeba histolytica for serodiagnosis of amebiasis and identification of immunodominant domains of the native molecule.

We expressed the gene that encodes one of the major surface antigens of Entamoeba histolytica, the 170-kDa protein (1,270 amino acids), as a glutathione S-transferase fusion protein containing amino acids 1 to 1202 (lacking the putative transmembrane and cytoplasmic regions) and as separate fusion proteins containing each of three major domains of the 170-kDa molecule. Lysates from bacteria induced to express one of these proteins were used as the target antigens in a Western blot (immunoblot) analysis to determine whether a recombinant 170-kDa antigen could serve as the basis for a serologic test used to detect invasive amebiasis and whether there are differences in humoral immunogenicity among the three major domains of the 170-kDa antigen. Among patients with invasive amebiasis from three major areas where the disease is endemic and two sites in the United States, 54 (90%) of 60 had antibodies to the recombinant 170-kDa protein. Among 37 patients from regions where the disease is endemic and 20 patients from the United States without amebic disease, 1 (2%) of 57 had antibodies to the recombinant 170-kDa protein. We found significant differences in seroreactivity to each of three major domains of the molecule among patients seropositive for the complete construct, ranging from 100% seroreactivity with the fusion protein containing the domain designated cysteine rich and 89% seropositivity with the fusion protein incorporating a portion of the region designated cysteine poor to only 9% seropositivity for the fusion protein containing the pseudorepeat domain. Our study indicates that a serologic test based on the recombinant 170-kDA antigen could serve as a highly sensitive and specific test for acute invasive amebiasis.

Animals↗
PubMed1992

Sensitive and specific serodiagnosis of invasive amebiasis by using a recombinant surface protein of pathogenic Entamoeba histolytica.

A recombinantly expressed protein, recEh-P1, representing part of an immunodominant surface antigen of pathogenic Entamoeba histolytica, was used for serodiagnosis of invasive amebiasis. Expression was performed under the control of a T7-RNA promoter by using a modified procaryotic expression vector, designated pHisT7. This vector allowed high-yield expression of recEh-P1 fused to a stretch of sequence containing eight histidine residues, which facilitated purification by metal chelate affinity chromatography on Ni2+ columns under highly denatured conditions. Purified recEh-P1 was found to be water soluble after prolonged dialysis and was used as the antigen for the detection of antiamebic serum antibodies by immunoblotting and enzyme-linked immunosorbent assay. In both tests all sera of patients with invasive amebiasis reacted to recEh-P1 whereas none of those collected from healthy controls, including individuals with noninvasive amebiasis, or from patients suffering from bacterial or protozoan infections unrelated to E. histolytica did so.

Amino Acid Sequence↗
PubMed1992

Extraintestinal amebiasis.

Extraintestinal involvement is a dreaded complication of amebiasis, with a reported mortality rate of 7%-14%. The authors retrospectively studied 188 patients with extraintestinal amebiasis confirmed by means of clinical, surgical, and radiologic criteria over a 45-month period. Ultrasonography (US) was the mainstay of radiologic investigation. Liver abscess was present in 183 patients (97%); five patients (3%) had other organ involvement but a normal liver. The majority of liver abscesses were in the right lobe. US is recommended for the diagnosis and follow-up of patients with extraintestinal amebiasis. It is noninvasive, simple, easily reproducible, and less expensive than computed tomography. Portable models can be taken into remote areas of the less-developed world.

Adult↗
PubMed1977

Endemic amebiasis in an extended family.

Two cousins from a large Spanish-American family were simultaneously diagnosed as having amebic liver abscesses. Survey of 183 extended-family members revealed that 45.7% of 162 had a positive amebiasis indirect hemagglutination test and 12.6% of 111 had cysts or trophozoites of Entamoeba histolytica demonstrated in a single stool examination. A total of five family members had had liver abscesses; two deaths had occurred. In a random sample survey of the remainder of the community, only one person (0.3%) had a positive serologic test. Within the extended family, person-to-person appeared to be the predominant mode of transmission. Water supplies were not contaminated. Both community and extended family homes had the same source of water. Type and source of food supply were not correlated with infection and there was no evidence to implicate an infected food handler. Clustering of seropositivity occurred in homes without indoor toilets. Homes of the extended family were more crowded and significantly fewer of them had indoor toilets. Endemic foci of amebiasis continue to exist in the United States. Follow-up family and other close contacts of persons with amebiasis will frequently identify other cases.

Feces↗
PubMed1978

Hepatic amebiasis in spider monkeys.

In the past, investigators have been able to produce hepatic amebiasis in laboratory animals only by direct introduction of parasites into the liver or its vasculature, or by other artificial manipulations. A natural model of human visceral amebiasis has been lacking. We document an extensive outbreak of amebic dystentery which took place in a colony of spider monkeys; severe hepatic abscesses occurred in many animals. The spider monkey is highly susceptible to infection with Entamoeba histolytica and could provide a valuable model for the study of the pathogenesis of invasive amebiasis.

Animals↗
PubMed1992

Use of an enzyme-linked immunosorbent assay to detect anti-adherence protein antibodies in sera of patients with invasive amebiasis in Cairo, Egypt.

We used enzyme-linked immunosorbent assay (ELISA) to detect IgG antibodies to the Entamoeba histolytica galactose-inhibitable adherence protein in the sera of 50 uninfected controls, 50 cases with asymptomatic cyst passage, 100 patients with amebic colitis, and six patients with amebic liver abscess from Cairo, Egypt, and in 50 healthy controls from the United States. When the mean + 3 SD value above that of the controls from the United States was used as a criterion for a positive ELISA result, 100% of those with invasive amebiasis, 80% of those with asymptomatic infection, and 64% of the Egyptian controls had anti-adherence protein antibodies. However, when the mean + 2 SD value of Egyptian control sera (optical density = 0.094) was used as the criterion for positivity, 33 (89%) of 37 sera from individuals with invasive amebiasis having symptoms for at least one week were antibody positive, in contrast to only 12% of asymptomatic cyst passers (P < 0.01). In a highly endemic area such as Cairo, Egypt, detection of serum anti-adherence protein antibodies by ELISA may have greatest diagnostic use in patients with symptomatic invasive amebiasis of greater than one week duration.

Animals↗
PubMed1978

Protective immunity and possible autoimmune regulation in amebiasis.

Hamsters were injected intradermally with axenic trophozoites of a pathogenic strain of Entamoeba histolytica, and controls similarly with culture medium. Localized lesions were produced in all animals injected with amebae. After the lesions healed all the animals were challenged intrahepatically with axenic amebae. Extensive liver abscesses were produced in all the controls, but a small abscess in only one of the vaccinated hamsters. In the protected animals the indirect hemagglutination antibody titers were high (I:512), while in the controls they ranged between 1:32 and 1:128. In the vaccinated hamster with the small abscess the IHA titer was 1:32. To investigate a possibility of autoimmune regulation in amebiasis, sera of hamsters with experimental amebic liver abscesses were acidified and tested by counter-current-immunoeletrophoresis against untreated autologous sera and amebic antigen. In most cases there was a direct correlation between the two titers. With human antisera in autologous systems there was reactivity against anti-amebic IgG antibodies. These experiments showed that autoimmune complexes may be present in cases of hepatic amebiasis. As in chronic hepatitis and some malignancies, it is possible that immune complexes have an immunoregulatory function in amebiasis.

Animals↗
PubMed2000

[Suburban amebiasis: the diagnostic aspects via computed tomography and echography and the percutaneous treatment of amebic liver abscesses].

INTRODUCTION: Liver is the most common site of extraintestinal amebiasis and hepatic abscesses are the most frequent symptom, occurring in 3-9% of patients with amebic infection. Several studies have shown that drug treatment is more efficacious when combined with percutaneous drainage of the abscess, yielding quicker recovery and a positive body response. We report our US and CT findings in 16 patients with amebic abscesses, 12 of whom lived in a temperate peripheral area north-east of Naples. All patients had a clinical-diagnostic condition that we called "suburban amebiasis". Finally we report our personal experience with the US-guided therapeutic drainage of amebic abscesses with repeated cavity washings, which is important for positive parasitology. MATERIAL AND METHODS: We retrospectively reviewed the findings of 16 patients (11 men and 5 women; age range 36-78 years; mean 52) with amebic abscesses of liver examined with US and CT. US with a 3.5 MHz transducer was the technique of choice in all patients. 94% of liver abscesses and some extraintestinal complications were easily shown with this technique. CT angiography was then performed to detail and clarify US findings. Abscesses over 4 cm in diameter were submitted to US-guided percutaneous treatment which permitted abscess drainage, the collection of material for parasitology and repeated cavity washings. RESULTS: US showed multiple liver abscesses in 12 patients, which were multiseptate and formed by multiple hypo-/hyperechoic microabscesses in 4 of them. Four non-European patients had a single abscess, which is typical of tropical endemic forms. CT showed the amebic abscesses as hypodense roundish masses with clear-cut outline most often localized in the right lobe in the 12 multiple cases. After percutaneous drainage 13/16 patients (81%) reported less pain in the right hypochondrium and had a lower temperature; their hospitalization was also shorter. DISCUSSION AND CONCLUSIONS: Combined US and CT assessment facilitated the diagnosis of amebiasis and its differentiation from pyogenic abscess and hepatoma. The combination of US-guided drainage and drug treatment provides better results than either treatment alone and quicker improvement of patient conditions, with fewer extraintestinal complications. Percutaneous drainage should be used in abscesses bigger than 4-5 cm, those with questionable clinical-laboratory findings and finally those failing to respond to drug treatment alone. Positive parasitology of abscess content is related to repeated cavity washings after percutaneous drainage, likely because peripheral layers are much richer in amebae.

Adult↗
PubMed2003

[Vulvar amebiasis. Report of a case and review of the literature].

Genital amebiasis by Entamoeba histolytica is rare, even in Mexico where the disease is endemic. We report a case of genital amebiasis in a female patient with a recto-perineal fistula and two-week history of a profuse vaginal discharge, a painful and friable vulvar ulcer and induration in gluteal and inner side of thighs. The PAP smear and the biopsy showed trophozoites, no malignant cells were observed. The findings were compatible with genital amebiasis. The serology test for E. histolytica was positive (> 1: 512). The patient was treated with metronidazol 750 mg tid for 3 weeks. Complete resolution was achieved. The long term fistula, the low socioeconomic status, the poor hygiene and diabetes mellitus of a recent onset were probably the risk factors associated to this infection. We reviewed the literature.

Entamoebiasis↗
PubMed1992

IgA reactivity in patients with intestinal or hepatic amebiasis.

The antigens of E. histolytica recognized by IgA antibodies in sera from patients with either amebic liver abscess or intestinal amebiasis, as well as saliva from the latter, were determined in immunoblots of whole native trophozoite proteins. Results show that sera of patients with amebic liver abscess reacted mainly with amebic proteins of more than 200 kDa, whereas those of individuals with intestinal amebiasis recognized a protein of 145 kDa. The saliva of the latter detected a protein of 210 kDa which is not always seen when using the sera of patients with intestinal or hepatic amebiasis.

Animals↗
PubMed1992

Serodiagnosis of invasive amebiasis using a recombinant Entamoeba histolytica antigen-based ELISA.

Amebic serology remains a critical component in the diagnosis of invasive amebiasis. A recombinant serine rich-Entamoeba histolytica-protein/maltose binding protein (SREHP/MBP) fusion protein was evaluated as the target antigen in an ELISA test to detect acute invasive amebiasis. Retrospective analysis of 65 serum samples from patients with amebic liver abscess and 40 asymptomatic control patients showed the SREHP/MBP ELISA test had a sensitivity of 74% and specificity of only 55% for the diagnosis of amebic liver abscess. This study was repeated under identical conditions using a purified recombinant SREHP cleaved from the MBP component. The purified recombinant SREHP-based ELISA had a sensitivity of 79% and specificity of 87%. Our data suggest a purified recombinant SREHP-based ELISA could prove useful in the serodiagnosis of acute invasive amebiasis.

Animals↗
PubMed2004

Amebiasis and comparison of microscopy to ELISA technique in detection of Entamoeba histolytica and Entamoeba dispar.

The analysis of records of amoebal infection in various hospitals in Kilimanjaro indicated frequent occurrence of amebiasis. The population over the age of five years had higher rate of amoebal infection compared to less than that of a five-year-old population; however, both age groups had similar patterns of amebiasis during January 1999 to June 2001. To investigate misdiagnosis of amebiasis, 226 patients (passive cases) in three hospitals and 616 individuals (active cases) from three different localities in Kilimanjaro were examined. In passive cases, the prevalences of Entamoeba histolytica and Entamoeba dispar were 1% and 7.3%, respectively. Among active cases, 1% were infected with E. histolytica, and 15% were infected with E. dispar. There were no significant differences in amoebal infection between the male and female populations. A pool of 842 stool samples was used for diagnosis of E. histolytica and E. dispar by microscopic examination or ELISA kits. The microscopic examination indicated 8.7% amoebal infection; however, using ELISA as the gold standard, the prevalence of histolytica/dispar was 0.8% and 7.4%, respectively. This study indicated that E. dispar infection was 14.5 times more prevalent than E. histolytica infection.

Animals↗
PubMedDate not supplied

[Diagnostic certainty in intestinal amebiasis in Managua].

Three surveys were carried out in Managua. Nicaragua. In the first one it was found that 71% of the intestinal amebiasis cases of obligatory notification had no comparable diagnostic foundations; in the second one, 11.7% of the laboratory diagnoses as Entamoeba histolytica referred by 4 health centers were correct; and in the third one, it was obvious that only 9.4% of the doctors knew well what intestinal amebiasis is. The results suggest that intestinal amebiasis is being diagnosed excessively in Managua.

Animals↗
PubMed1991

[Histopathology of experimental hepatic amebiasis].

The method of intrahepatic inoculation was successfully used to establish an experimental model of hepatic amebiasis in golden hamsters for studying its pathological morphology. Three types of macroscopic liver lesions, i.e., isolated abscess, multinodular abscess and ruptured lesion were described. On light microscopy the alteration and the proliferation type lesions were found as distinct pathological characteristics of the early and advanced hepatic amebiasis respectively. The development pattern of hepatic amebiasis and the pathogenicity of Entamoeba histolytica were discussed.

Animals↗