Amebiasis and Amebic Liver Abscess in Children.

Although rare in the developed world, amebiasis continues to be a leading cause of diarrhea and illness in developing nations with crowding, poor sanitation, and lack of clean water supply. Recent immigrants or travelers returning from endemic regions after a prolonged stay are at high risk of developing amebiasis. A high index of suspicion for amebiasis should be maintained for other high-risk groups like men having sex with men, people with AIDS/HIV, immunocompromised hosts, residents of mental health facility or group homes. Clinical presentation of intestinal amebiasis varies from diarrhea to colitis and dysentery. Amebic liver abscess (ALA) is the most common form of extraintestinal amebiasis. Various diagnostic tools are available and when amebiasis is suspected, a combination of stool tests and serology should be sent to maximize the yield of testing. Treatment with an amebicidal drug such as metronidazole/tinidazole and a luminal cysticidal agent such as paromomycin for clinical disease is indicated. However, for asymptomatic disease treatment with a luminal cysticidal agent to decrease chances of invasive disease and transmission is recommended.

Intestinal amoebiasis: 160 years of its first detection and still remains as a health problem in developing countries.

Amoebiasis is a parasitic disease caused by Entamoeba histolytica (E. histolytica), an extracellular enteric protozoan. This infection mainly affects people from developing countries with limited hygiene conditions, where it is endemic. Infective cysts are transmitted by the fecal-oral route, excysting in the terminal ileum and producing invasive trophozoites (amoebae). E. histolytica mainly lives in the large intestine without causing symptoms; however, possibly as a result of so far unknown signals, the amoebae invade the mucosa and epithelium causing intestinal amoebiasis. E. histolytica possesses different mechanisms of pathogenicity for the adherence to the intestinal epithelium and for degrading extracellular matrix proteins, producing tissue lesions that progress to abscesses and a host acute inflammatory response. Much information has been obtained regarding the virulence factors, metabolism, mechanisms of pathogenicity, and the host immune response against this parasite; in addition, alternative treatments to metronidazole are continually emerging. An accesible and low-cost diagnostic method that can distinguish E. histolytica from the most nonpathogenic amoebae and an effective vaccine are necessary for protecting against amoebiasis. However, research about the disease and its prevention has been a challenge due to the relationship between E. histolytica and the host during the distinct stages of the disease is multifaceted. In this review, we analyze the interaction between the parasite, the human host, and the colon microbiota or pathogenic microorganisms, which together give rise to intestinal amoebiasis.

Varied Clinical Manifestations of Amebic Colitis.

Invasive amebiasis is common worldwide, but infrequently observed in the United States. It is associated with considerable morbidity in patients residing in or traveling to endemic areas. We review the clinical and endoscopic manifestations of amebic colitis to alert physicians to the varied clinical manifestations of this potentially life-threatening disease. Copyright ©Most patients present with watery or bloody diarrhea. Less common presentations of amebic colitis include abdominal pain, overt gastrointestinal bleeding, exacerbation of inflammatory bowel disease, or the incidental association with colon cancer. Amebic liver abscesses are the most frequent complication. Rectosigmoid involvement may be found on colonoscopy; however, most case series have reported that the cecum is the most commonly involved site, followed by the ascending colon. Endoscopic evaluation should be used to assist in the diagnosis, with attention to the observation of colonic inflammation, ulceration, and amebic trophozoites on histopathological examination.

Burden of major diarrheagenic protozoan parasitic co-infection among amoebic dysentery cases from North East India: a case report.

Intestinal diarrheagenic polyparasitic infections are among the major public health concerns in developing countries. Here we examined stool specimens by microscopy, DNA dot blot and polymerase chain reaction (PCR) to evaluate the co-infection of four principal protozoans among amoebic dysentery cases from Northeast Indian population. The multiplex PCR confirmed Entamoeba histolytica (8.1%), Entamoeba dispar (4.8%) and mixed infection of both the parasites (3.4%) in 68 of 356 stool specimens that were positive in microscopy and/or HMe probe based DNA dot blot screening. The prevailing parasite that co-exists with E. histolytica was Giardia duodenalis (34.1%), followed by Enterocytozoon bieneusi (22.0%), Cryptosporidium parvum (14.6%) and Cyclospora cayetanensis (7.3%, P = 0.017). Symptomatic participants (odds ratio (OR) = 4.07; 95% confidence interval (CI) = 1.06, 15.68; P = 0.041), monsoon season (OR = 7.47; 95% CI = 1.40, 39.84; P = 0.046) and participants with family history of parasitic infection (OR = 4.50; 95% CI = 1.16, 17.51; P = 0.030) have significant association with overall co-infection rate. According to molecular consensus, comprehensive microscopy yielded 3.4% (12/356) false-negative and 7.6% (27/356) false-positive outcome, suggesting an improved broad-spectrum PCR-based diagnostic is required to scale down the poor sensitivity and specificity as well as implementation of integrated control strategy.

Efficacy and safety of paromomycin for treating amebiasis in Japan.

The clinical management of amebiasis is a growing concern, particularly among human immunodeficiency virus (HIV)-infected individuals who are predisposed to severe illness. Treatment with a luminal amebicide is strongly recommended following acute-stage treatment with a nitroimidazole. In 2004, the Japanese Research Group on Chemotherapy of Tropical Diseases introduced paromomycin, which was not nationally licensed, and offered it to a number of patients. From 2004 to 2011, 143 case records of amebiasis (123 with amebic colitis, 16 with amebic liver abscess, and 4 with both) in which patients were treated with paromomycin, mainly 1,500 mg/day for 9 or 10 days following metronidazole treatment, were submitted. Among 123 evaluable cases, 23 (18.7%) experienced possible adverse effects, the most common being diarrhea (17/123, 13.8%) and other gastrointestinal problems that were resolved after the completion or discontinuation of treatment. In addition, single cases of bloody stools associated with Clostridium difficile colitis, skin rash, and the elevation of liver enzymes were also reported, although the causal relationship was not clear. HIV infection did not appear to increase the incidence of adverse drug effects. Each of the 11 asymptomatic or mildly symptomatic amebic colitis cases became negative for stool cysts after paromomycin treatment. Paromomycin was shown to be safe and well tolerated, as well as effective in a special subset of amebic colitis cases.

[The distribution of intestinal parasites detected in the Uludag University Medical Faculty Hospital between 2009-2010]. / Uludag Üniversitesi Tip Fakültesi Hastanesinde 2009-2010 Yillarinda Saptanan Bagirsak Parazitlerinin Dagilimi

OBJECTIVE: Intestinal parasite infection is still an important public health problem. In this study, patients with various gastrointestinal system complaints presenting at various clinics of the Uludag University Medical Faculty, between 2009-2010 were investigated for intestinal parasites. METHODS: All fecal samples were examined with the formol ethyl acetate sedimentation method for helminth ova and protozoan cysts. For the diagnosis of coccidian protozoa, the modified Ehrlich-Ziehl-Neelsen was used. Trichrome staining was also performed in ambiguous cases. The cellophane tape method was used to detect Enterobius vermicularis egg. The prevalence of intestinal parasites was evaluated with respect to age, gender and the months in which cases were seen. RESULTS: One or more parasites were found in 195 of the 2686 stool samples. The overall prevalence of intestinal parasitic infection rate was 7.3%, and of these patients, 57.95% were female and 42.05% male. Predominant parasites were Giardia intestinalis 3.23%, followed by Entamoeba coli 2.34%, Entamoeba histolytica 0.59%, and Strongyloides stercoralis 0.44%. Enterobius vermicularis eggs were detected by the cellophane tape method in 80 (12.08%) out of 622 patients. The proportion of individuals infected with one parasite was 85.4%, two parasites 12.6%, and three parasites 2.0%. The age group 10-19 years had the highest prevalence of parasites and was predominantly infected with G. Intestinalis (p < 0.001). CONCLUSION: The results of this study emphasized that, even in the Bursa Province with a relatively high level of social hygiene, intestinal parasitic infections are still an important public health problem.

Entamoeba species associated with chronic diarrhoea in Pakistan.

We determined the prevalence of Entamoeba (E.) histolytica, E. dispar and E. moshkovskii in patients with chronic diarrhoea associated with abdominal pain or discomfort mimicking irritable bowel syndrome. Stool samples were collected from 161 patients with chronic diarrhoea and from 157 healthy controls. Stool microscopy with modified trichrome stain, culture and polymerase chain reaction (PCR) for Entamoeba spp. differentiation was performed. Microscopy demonstrated Entamoeba cysts in 44% (57/129) of patients with diarrhoea compared to 29% (44/151) of controls (P=0·009). In patients with diarrhoea, PCR for E. histolytica was positive in 9% (11/129) (P=0·008), E. dispar in 19% (24/129) (P=0·117) and E. moshkovskii in 19% (24/129) (P<0·001). E. histolytica and E. moshkovskii were significantly associated with diarrhoea while E. dispar was found equally in both groups.

Association between TNF-alpha and Entamoeba histolytica diarrhea.

An association between tumor necrosis factor alpha (TNF-alpha) and Entamoeba histolytica diarrhea was assessed in a cohort of 138 non-related Bangladeshi children who have been prospectively followed since 2001. Peripheral blood mononuclear cells (PBMCs) obtained at study entry were purified, cultured, and stimulated with soluble amebic antigen before cytokine measurement from supernatant. Higher levels of TNF-alpha were associated with increased risk of first (P = 0.01) and recurrent E. histolytica-related diarrheal episodes (P = 0.005). Children who developed E. histolytica diarrhea had significantly higher TNF-alpha protein levels than those who experienced asymptomatic E. histolytica infection (P value = 0.027) or no infection (P value = 0.017). Microarray studies performed using RNA isolated from acute and convalescent whole blood and colon biopsy samples revealed higher but non-significant TNF-alpha messenger RNA (mRNA) levels in subjects with acute E. histolytica diarrhea compared with convalescence. We conclude that there is an association between higher TNF-alpha production and E. histolytica diarrhea.

[Disentery and hepatic abscess in the colonial and republican Chile. Doctor Miguel Claro Vásquez]. / Disentería y absceso hepático en el Chile colonial y republicano: El Doctor Miguel Claro Vásquez.

The frequency and severity of dysentery and hepatic abscess during the colonial and republican era in Chile are reviewed. The amebian etiology was confirmed in both clinical entities. Also, Miguel Claro Vásquez, physician and later priest and bishop of the Catholic Church, was distinguished for his contribution to hepatic abscess surgery.

Disentería y absceso hepático en el Chile colonial y republicano: El Doctor Miguel Claro Vásquez / Disentery and hepatic abscess in the colonial and republican Chile: Doctor Miguel Claro Vásquez

The frequency and severity of dy sentery and hepatic abscess during the colonial and republican era in Chile are reviewed. The amebian etiology was confirmed in both clinical entities. Also, Miguel Claro Vásquez, physician and later priest and bishop of the Catholic Church, was distinguished for his contribution to hepatic abscess surgery.

En esta comunicación se destaca la frecuencia y gravedad en Chile, durante la época colonial y republicana, de dos entidades clínicas: disentería y absceso hepático, comprobándose finalmente la etiología amebiana en ambos procesos. Además se distingue al doctor Miguel Claro Vásquez, médico, después sacerdote y obispo de la Iglesia Católica, por su aporte a la cirugía del absceso del hígado.

[Epidemiological investigation on an outbreak of amoebic dysentery in Jiangshan City of Zhejiang Province].

The investigation was carried out from 15 May to 10 June 2006 among diarrhea patients of two schools and periphery residents in Hecun Town, Jiangshan City. Stool samples were examined for Entamoeba histolytica. Water samples were taken for microbial analysis. 31 cases with E. histolytica were found,with 74.2% (23 cases) of students and preschool children. 9 cases were found in Liuyi kindergarten and 8 cases in Hecun central primary school with a prevalence of 7.4% and 0.65%, respectively. Among 594 asymptomatic close contactors, 9 cases (1.5%) were carriers of cysts. Of the 31 cases, 22 were found with no habit of handwashing before eating or after defecation, and 14 cases had a close contact to the patients. No amoebic cysts or trophozoites were found from 12 water samples collected from schools or patient's houses, but the Escherichia coli level exceeded the national standard in 7 samples.

[Epidemiologic and molecular study of Entamoeba histolytica and Entamoeba dispar strains in pacients with diarrhea in Cumana, Sucre state, Venezuela]. / Estudio epidemiológico y molecular de cepas de Entamoeba histolytica y Entamoeba dispar en pacientes con diarrea en Cumaná, estado Sucre, Venezuela.

An epidemiological and molecular study on E. histolytica and E. dispar was carried out in 428 patients with gastrointestinal symptomatology of diarrhea from different health centers in Cumana, Sucre state. The samples were processed through: direct examination with 0.85% physiological saline solution, temporal lugol staining, trichromic staining and the Ritchie method of concentration; a sucrose gradient was used for cyst isolation. The small subunit of the 16S RNA was amplified by nested, multiplex PCR for the molecular detection. The E. histolytica/E. dispar prevalences according to the direct, Ritchie and trichromic staining methods were 20.09, 13.79 and 12.15%, respectively; while prevalences according to PCR for E. histolytica and E. dispar were 6.31% and 4.44%, respectively, also detecting four cases of mixed infection. Sequencing of the amplified fragments of E. histolytica showed 100% homology with the sequences with strains from Merida (Venezuela), USA, Brazil, Mexico and GenBank. The infections by E. histolytica and E. dispar were statistically associated with age but not with sex. The presence of mucus, blood and abdominal pain were only associated to E. histolytica infection. The moderate prevalence of E. histolytica shows the endemic status of this population and warns about the potential problem as a morbidity and mortality in Sucre state. The frequency of E. dispar in this population suggests the existence of an overestimation problem in the diagnosis of amoebiasis with its clinical and epidemiological implications, and shows the poor knowledge about the true prevalences of this protozoan. The PCR allowed for the differential identification of E. histolytica and E. dispar, as well as the presence of mixed infections, making a great tool for epidemiological amoebiasis studies.

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.

Entamoeba histolytica and Entamoeba dispar infections in cynomolgus monkeys imported into Japan for research.

Three hundred and three stool samples of cynomolgus monkeys (Macaca fascicularis) imported from China and the Philippines were examined for Entamoeba histolytica/Entamoeba dispar infections. Microscopy detected E. histolytica/E. dispar cysts in 41 samples. Positive rates were higher in the monkeys from China (37.5%) than in the monkeys from the Philippines (3.7%). PCR analysis of 25 samples successfully cultured from the cysts demonstrated that 24 were E. dispar, one of the samples from China was E. histolytica. The one sample was also identified as E. histolytica by an antigen detection kit, although the monkey was asymptomatic and serology was negative. To our knowledge, this is the first report of E. histolytica isolation from cynomolgus monkeys based on the discrimination between E. histolytica and E. dispar.

Comparison of two methods (microscopy and enzyme-linked immunosorbent assay) for the diagnosis of amebiasis.

Diagnosis of amebiasis is usually performed on a clinical basis alone in most endemic countries having limited economic resources. This epidemiological study was conducted using modern diagnostic tests for amebiasis in the southeastern region of Turkey, an endemic area for amebiasis. The population of this study included patients with symptomatic diarrhea/dysentery attending both Yuzuncu Yil University, Van and Harran University, Sanliurfa, Turkey. A total of 380 stool specimens were collected and examined for Entamoeba by light microscopy (fresh, lugol, and trichrome staining) and stool antigen detection based- enzyme-linked immunosorbent assay (EIA) test (TechLab Entamoeba histolytica II). 24% (91/380) of stool specimens were positive for E. histolytica/Entamoeba dispar trophozoites/cysts microscopically using trichrome staining. 13% (51/380) of the stool specimens were found to be positive for E. histolytica by the EIA test, including 15% (14/91) of microscopy (+) stool specimens and 13% (37/289) of microscopy (-) stool specimens. Enteric parasites were common in these populations with 66% (251/380) of the study population harboring more than one parasite. In addition to the 13% (51/380) of patients determined to have E. histolytica by EIA, eighty-six patients (22.6%) had Blastocystis hominis, 54 (14.2%) Entamoeba coli, 44 (11.5%) Giardia lamblia, 16 (4.2%) Chilomastix mesnili, 15 (3.9%) Iodamoeba bütschlii, 12 (3.1%) Hymenolepis nana, 9 (2.3%) Endolimax nana, 9 (2.3%) Dientamoeba fragilis, and 8 (2.1%) had Ascaris lumbricoides. We concluded that E. histolytica infection was found in 13% of the patients presenting with diarrhea in Van and Sanliurfa Turkey.

[Outbreak of amoebiasis in a Dutch family; tropics unexpectedly nearby]. / Uitbraak van amoebiasis in een Nederlands gezin; tropen onverwacht dichtbij.

An amoebic liver abscess, amoebic dysentery and asymptomatic cyst passage were diagnosed in a father, a mother and one of their three children, respectively. One of the other children had been in the tropics, but only after the father's symptoms had begun. All three family members were infected with the same strain of Entamoeba histolytica as determined by polymerase chain reaction (PCR)-based DNA typing. The source of infection was most probably in Southern Italy where the family regularly spent their summer holidays. All three infected patients recovered after drug treatment. In a patient with a liver abscess or colitis, amoebiasis should be considered even in the absence of a history of a stay in the tropics. Stool samples should be examined for amoebic cysts and trophozoites. PCR analysis of parasite DNA extracted directly from stool samples makes differentiation between the morphologically identical cysts of E. histolytica and the non-pathogenic Entamoeba dispar possible. In addition, serum antibodies to E. histolytica are almost always present in symptomatic patients. Invasive infections with E. histolytica require treatment with a tissue amoebicidal drug, followed by a contact amoebicide to prevent recurrence. Currently, paromomycin is considered to be the first-line luminal amoebicide because of its efficacy and safety.

Prevalencia de la Entamoeba histolytica en asentamientos temporales post terremoto de la ciudad de Armenia / Entamoeba histolytica prevalence in temporary housing after the earthquake, Armenia, Colombia

Objetivo: determinar la prevalencia de parásitos intestinales y de Entamoeba histolytica mediante la prueba ELISA de adhesina en heces en asentamientos temporales post-terromoto. Diseño: estudio de prevalencia de punto. Lugar: ocho asentamientos temporales post-terremoto de la ciudad de Armenia. Población: muestra representativa de la población entre 4 y 65 años de edad de asentamientos, en total 169 personas. Mediciones: coproscópico y prueba ELISA para adhesina de Entamoeba histolytica en heces. Resultados: Endolimax nana fue el parásito comensal más prevalente con 66 por ciento, seguido por Entamoeba coli 26 por ciento y Lodamoeba buschtlii 10 por ciento. Giardia lamblia fue la especie patógena más prevalente con 38 por ciento, seguida de Ascaris lumbricoides 10 por ciento, Strongyloides stercoralis 2 por ciento, Trichuris trichura 1.7 por ciento, Hymenolepsis nana 0.6 por ciento (1/169). Los quistes de Entamoeba histolytica/dispar fueron detectados por microscopía en 17.5 por ciento y la prueba de adhesina fue positiva en sólo una de las 169 muestras estudiadas (0.6 por ciento). Conclusiones: este estudio señala que E. histolytica es poco frecuente en asentamientos temporales post-terremoto y la necesidad en Colombia de realizar pruebas específicas, con el fin de determinar la instauración de un tratamiento antiamibiano, el cual no se puede basar en el resultado de la microscopía óptica dada la alta frecuencia de amibas no patógenas

[Epidemiological, clinical and parasitological data concerning intestinal amebiasis in northern Tunisia]. / Données épidémiologiques, cliniques et parasitologiques concernant l'amibiase intestinale dans le nord de la Tunisie.

In order to evaluate the principal characteristics of the intestinal amoebiasis in the north of Tunisia, one retrospective study review all cases diagnosed in principal gastroenterologic sections of the hospitals of Tunis. Twenty height cases of intestinal amoebiasis, 10 of which have an inflammatory bowel disease associated were included. Watery stools containing blood and mucus were the most important symptoms (25 cases). The endoscopic exam showed for all the cases non specific lesions. The diagnosis was based on histologic exam in 21 cases, on the positivity of serologic tests in 3 cases and on the presence of E. histolytica/dispar cysts in stools in 6 cases. In two cases, the diagnosis was made by therapeutic test.

Overdiagnosis of amoebiasis in the absence of Entamoeba histolytica among patients presenting with diarrhoea in Wonji and Akaki, Ethiopia.

To confirm the high reported incidence of intestinal amoebiasis among study participants at 2 cohort sites in Ethiopia where an HIV/AIDS study is taking place, stool samples of 232 patients with complaints of diarrhoea were examined for the presence of Entamoeba histolytica and E. dispar DNA between April and December 2001. By microscopy, 91 (39%) of the study participants were reported to harbour Entamoeba trophozoites and/or four-nucleated cysts. Using specific E. histolytica and E. dispar DNA amplification and detection, none of the study participants were found to be infected with E. histolytica and only 21 (9%) with E. dispar. The consequences of the overdiagnosis of E. histolytica are briefly discussed.

Intestinal parasites in children with diarrhea in Delhi, India.

The parasitic causes of diarrhea in children in Delhi were determined by the direct smear technique; stool specimens of 127 children were examined for intestinal parasites. In 59 cases (46.5%) intestinal helminths and protozoa were demonstrated. Ascaris lumbricoides was observed in 1 (0.8%) case, while Trichuris trichiura was the finding in 3 (2.4%). Protozoal parasites included Giardia intestinalis and Entamoeba histolytica in 14 (11%) cases each, Balantidium coli in 3 (2.4%) cases and Cryptosporidium spp in 24 (18.9%) patients. Mixed infection was not seen in any of the cases. Intestinal parasites may increase susceptibility to infection with other intestinal pathogens and therefore with the help of a simple technique, like direct fecal smear examination. rapid diagnosis can be made and specific therapy instituted.