Entamoeba Histolytica Research Articles

Progress in the research on diagnosis and vaccines in amebiasis.

Entameba histolytica causes amebiasis, which includes both intestinal and extraintestinal amebiasis. E. histolytica causes 34 million to 50 million symptomatic cases of amebiasis worldwide every year, causing 40 thousand to 100 thousand deaths annually. E. histolytica, the pathogenic species of amebae is indistinguishable in its cyst and trophozoite stages from those of E. moshkovskii, a free-living ameba, and E. dispar, a non-invasive ameba, by microscopy, except in cases of invasive disease, where E. histolytica trophozoite may contain ingested red blood cells, but such a finding is rarely seen. This leads to a confusing scenario for the definite identification and differentiation of E. histolytica from E. moshkovskii and E. dispar by conventional microscopy, in the diagnosis of intestinal amebiasis. The advent of molecular methods such as multiplex PCR and real time PCR have facilitated a better and accurate diagnosis of E. histolytica, E. moshkovskii, and E. dispar in stool, urine, saliva, and other specimens. Multiplex PCR for the diagnosis of amebic liver abscess, using urine and saliva as clinical specimens, has been used, and the results have been encouraging. Real-time PCR is a new and a very attractive methodology for laboratory diagnosis of amebiasis, because of its characteristics that eliminate post-PCR analysis, leading to a shorter turnaround time. Microarray-based approaches represent an attractive diagnostic tool for the detection and identification of amebae in clinical and epidemiological investigations. 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, which is required for protection against amebiasis. Thus, it is just a matter of time, and hopefully, amebiasis vaccine for human trials will be available in the next few years.

Neonatal amoebiasis

The authors report a case of neonatal amebiasis presenting with vomiting, refusal to feeds, abdominal distension and mucoid stools. The diagnosis was made on the basis of clinical appearance of stools and the presence of Entameba Histolytica. The purpose of this report is to alert to the possibility of amoebiasis in newborns, if baby presents with NEC like picture in an endemic area and to send the stool sample immediately to examine for trophozoites, especially because the diarrheal stool starts autolyzing within 30 min of defecation. This 14-day-old newborn, who was possibly infected with orally given jaggery solution is presented. He was successfully treated with intravenous tinidazole.

Antigen detection of entamoeba histolytica intestinal infection: cost-associated challenge in a resource poor country

Purpose: Laboratory diagnosis of Entamoeba histolytica infection is still being made through compound light microscopy in resource limited countries despite the associated flaws. This study is aimed at applying and determining the usefulness of ELISA antigen detection technique for E. histolytica intestinal infection diagnosis in a resource poor nation. Methods: A total of 150 subjects with acute and persistent diarrhoea had their stool specimens examined by compound light microscopy for E. histolytica/dispar and other intestinal parasites. Ninetyfour of them (62.67%) had their stool specimens examined with ELISA antigen detection for E. histolytica Results: Two (1.33%) of the subjects were positive for E. histolytica/ dispar on microscopy but none was positive for E. histolytica by ELISA antigen detection. Subjects positive by microscopy were identified as E. dispar (1.33%) carriers. Conclusion: ELISA antigen detection technique is a preferred method of detection of parasites even in resource poor settings to avoid confusing results. At present, the best use of E. histolytica II kit in resource poor nations should be limited to screening of E. histolytic/dispar microscopically positive stool samples for E. histolytica infection. Keywords: Amoebasis; Antigen detection; ELISA; Entamoeba histolytica; Laboratory diagnosis; Nigeria.

Antigen detection of entamoeba histolytica intestinal infection: cost-associated challenge in a resource poor country

Antigen detection of entamoeba histolytica intestinal infection: cost-associated challenge in a resource poor country

How to live with short bowel syndrome?

Introduction: Absorption of nutrients in short bowel syndrome (SBS) is seriously impaired. The adequate treatment of SBS are parenteral and enteral fluid, electrolyte, nutrient and vitamin substitutions. If more than 80 percent of the small bowel is resected, generally life-long total or supplementary parenteral nutrition is required. A 63 year-old male patient with the hystory of ulcerative colitis and mesalazine therapy since 1986 has been treated several times for entamoeba histolytica and dyspar infection. In 2003 the relapse of ulcerative colitis was treated with olsalazine and parenteral methyprednisolon, but on the second day of therapy acute abdomen developed. Laparotomy revealed ileal necrosis. Resection and later reresection was necessary due to progressive ileal necrosis. In 2004 subtotal colectomy, ileostomy with rectal restoration and also ileal segment resection were performed for necrosis. After the surgery only 80cm of small bowel remained. His weight decreased from 79 to 50kg, laboratory tests showed severe malnutrition, electrolyte disorder and frequent tetanic cramps occured. Initially parenteral infusion with calcium, potassium, magnesium and orally Protifar, Fantomal and Ensure were administered. Since 2005 the patient has been on methylprednisolone, oral and rectal mesalamine, high-dose oral potassium, calcium, magnesium, ferrous sulfate, folic acid, A, B1, B6, C, E vitamins. At present the patient is symptom-free, and only fed orally, and his laboratory parameters are normal. In the last 5 years his body weight has been constant at 55kg, and there was no need for hospitalization. Conclusion: Our case demonstrates possible adaptation in the absorption of small intestine, therefore the expansive and uncomfortable parenteral nutrition can be replaced to enteral nutrition.

Cardiac Tamponade Due to Liver Amebiasis Rupture

Amebiasis is common cases in Asia, Africa, and South Africa. Liver amebiasis has become a serious problem worldwide especially in health and social aspect. The protozoa named Entamoeba histolytica was easily found in area with poor sanitation, low socioeconomic status, and poor nutrition status. The incidence of amebiasis in several hospitals in Indonesia is 5-15% per year. Epidemiological observation showed the comparison of incidence among male and female population and it was approximately 3 : 1 until 22 : 1 with male predominance. The potential age suffered from amebiasis is around 20 - 50 years old. The route of infection spread to oral-fecal and oral-anal-fecal. The most common complication is abscess rupture (5-15.6%). Rupture may be located in pleural cavity, pericardial cavity, lung, bowel, intraperitoneal, and skin. Rupture of liver amebias spread to pleural and pericardial cavity is a rare case and frequently under reported. This case report illustrates a 40-year-old male with cardiac tamponade due to rupture of liver amebiasis. Patient’s was admitted with chief complaint of shortness of breath, positive Beck’s triad, hepatomegaly, pleural effusion, liver abscess on sonography and swinging of heart on echocardiography. This patient was treated with metronidazole as a drug of choice, and pericardiocentesis for the cardiac tamponade. Keywords: cardiac tamponade, Entamoeba histolytica, oral-anal-fecal, metronidazole, pericardiocentesis

Etiological approach to chronic urticaria

Background:In 1769, William Cullen introduced the word “urticaria” (transient edematous papules, plaque with itching). Urticaria affects 15-25% of people at least once in their life time. It is a clinical reaction pattern triggered by many factors causing the liberation of vasoactive substances such as histamine, prostaglandins and kinins. Urticaria is classified according to its duration into acute (< 6 weeks duration) and chronic (>6 weeks duration). Various clinical investigations may be initiated to diagnosis the cause.Aims:To evaluate the types of chronic urticaria with reference to etiology from history and investigations.Materials and Methods:A total of 150 patients with chronic urticaria of more than six weeks were studied. Autologous serum skin test (ASST) was performed after physical urticarias were excluded. Standard batteries of tests were performed after ASST in all patients; and other specific investigations were done where necessary. Skin prick test was done in idiopathic urticaria.Results:The study sample consisted of 62 male and 88 female patients with a mean age of 21-40 years. About 50% of patients showed an ASST positive reaction, 3.9% were positive for antinuclear antibody (ANA), IgE titer was elevated in 37%, H. pylori antibodies was positive in 26.7%. Thyroid antibodies were positive in 6.2%. Giardia and entamoeba histolytica was reported in 3.3% on routine stool examination and on urinalysis 8% had elevated WBC counts; 12% showed para nasal sinusitis, with maxillary sinusitis of 7.3%. Random blood sugar was high in 5.3%. Four patients had ASOM, two had positive KOH mount for dermatophytes, abdominal USG showed cholecystitis in two patients. Recurrent tonsillitis was noted in two patients. Urticaria following intake of NSAIDs was observed in four patients and with oral contraceptive pills in one patient. Contact urticaria to condom (latex) was seen in one patient. Cholinergic (4.7%) and dermographic (4.7%) urticaria were the predominant physical urticarias. Prick test was performed in idiopathic urticaria with maximum reactions to food antigens (25%) where brinjal was the commonest, 9% to dust in which spider web was the most common, 8% to pollen where parthenium and amaranthus were the commonest, followed by A. flavus in fungi, pigeon in epithelia and cockroach in insects.Conclusion:Nearly half of the patients had chronic autoimmune urticaria on the basis of ASST. A significant number of them had serological makers of autoimmune activity. ASST provides an easy, inexpensive investigation in CU and helps direct attention to underlying systemic auto immune diseases. The presence of these auto antibodies was significantly associated with more frequent and longer lasting urticarial attacks. Exhaustive work ups with extensive laboratory diagnostics, challenge tests, and prick testing should be reserved for individual cases following detailed history.

Acute amebic appendicitis: Report of a rare case

Acute appendicitis of amebic origin is considered a rare cause of acute appendicitis. We report a case of amebic appendicitis presenting with fever, severe pain in the right lower quadrant of the abdomen and rebound tenderness. Lab investigations revealed neutrophilic leukocytosis. The patient underwent appendectomy. Histopathological examination revealed numerous Entameba histolytica trophozoites in the mucosa of the appendix. Acute appendicitis of amebic origin does not appear frequently. Appendicular amebiasis can give the clinical features of acute appendicitis and should be treated accordingly.

Intestinal amoebiasis in children and its effect on nutritional status.

To determine the frequency and clinical presentation of amoebic diarrhea in children and its effect on the nutritional status of the affected children. Descriptive. Department of Diarrhea Treatment Unit (DTU), Dow Medical College and Civil Hospital, Karachi, from November 1998 to April 2001. Paediatric patients between the ages of > 1 month to 15 years were included, who visited the DTU of the department with diarrhea. Stool samples of all these patients were checked under microscope for the vegetative forms of Entamoeba Histolytica (E.H.). Patients who were positive for E.H. were evaluated for the symtomatology including the type of diarrhea {acute watery diarrhea (AWD) or dysentery}, abdominal pain, tenesmus and nausea/vomiting. Examination carried out was assessed for state of hydration, fever and anaemia and nutritional status of those less than 5 years of age. The patients were divided into three age groups to assess the association of the age with severity and type of clinical presentation. Chi- square test was applied to calculate the p-values. P-values of 0.05 or less were considered statistically significant. The stool samples of 3870 patients with diarrhea were examined under microscope. Three hundred and twenty eight (8.47%) of these samples were positive for E.H. The difference between the number of patients presenting with acute watery diarrhea n=157, 47.86% and with dysentery n=171, 52.13% was found to be statistically non-significant (p=0.364). Two hundred and seventy seven (84.45%) patients had tenesmus, while abdominal pain was present in 287 (87.5%). Fever and malnutrition were present in 169 (51.52%) patients each. Malnutrition was significantly most frequent in 1-5 years of age groups (n=98, 57.98%, p=0.026). The nutritional evaluation of the 272 under-5 children with amoebic diarrhea showed a significantly normal status in 123 (45.55%, p-value < 0.001). All the signs and symptoms followed a similar trend with 1-5 years age group being the most affected group. However, the frequency of blood in stools increased in direct proportion to the increasing age. Although dysentery was the more common presenting complaint, almost half of the patients presented with watery diarrhea. Most of the patients with dysentery were under the age of 5 years. Fever was present in a high number of patients. The age group most affected by amoebiasis and malnutrition was 1-5 years.

Clinical Efficacy of Saccharomyces boulardii and Metronidazole Compared to Metronidazole Alone in Children with Acute Bloody Diarrhea Caused by Amebiasis: A Prospective, Randomized, Open Label Study

The aim was to evaluate the efficacy of Saccharomyces boulardii (Sb) in addition to metronidazole in amebiasis. A prospective, randomized, open clinical trial was performed in 50 children presenting with acute bloody diarrhea caused by Entameba histolytica. Group A and B (each N = 25) was treated with metronidazole, but Sb (250 mg, twice daily) during the 7 days was added to Group B patients who were re-evaluated 2, 3, 5, 10, and 30 days after diagnosis. Duration of bloody diarrhea was significantly longer in Group A (72.0 +/- 28.5 versus 42.2 +/- 17.4 hours, P < 0.001). On day 5, amebic cysts had disappeared in all children in Group B, whereas in Group A, amebic cysts were still present in 6 children (P < 0.05). On day 10, all children were cured and cysts had disappeared in all. The addition of Sb to metronidazole in amebiasis significantly decreases duration of (bloody) diarrhea and enhances clearance of cysts.

Infectious Colitis: Diagnosis and Treatment

Generally, the term infectious colitis is the same with the term infective colitis. Infective or infectious colitis can be defined as colon inflammation due to infections or infectious organism. In Indonesia the most frequent cause of acute or chronic colitis is still infections. From researches, we know that the frequent cause of infective colitis were bacterias (pathogenic Escherichia coli, Clostridium difficile, Salmonella, Shigella, Campylobacter, etc), parasites (Entamoeba histolytica), helminth (Trichuriasis, Strongiloides, etc). Most infections of these causes are food borne illnesses or food poisoning. The clinical manifestations of infective or infectious colitis are fever, abdominal pain, diarrhea or constipation, bloating etc. Diagnosis of infective colitis is made by history taking (anamnesis), physical examination, supporting laboratories (blood, stool), and colonoscopy/sigmoidoscopy examination. From the history we can have a history which the patient contacted the infected people, recent mountain camping or travel abroad, drinking unpurified water, eating raw meat, seafood, or unhygienic food preparation, recent uses of antibiotics. Bloody diarrhea, fever and tenesmus (pain on defecation) are the clue for inflammatory enterocolitis or systemic disease. Physical examination can find abnormalities such as dehydration, hyperactive bowel sounds, abdominal tenderness etc. The findings that showed dehydration are dry mucous membranes, sunken eyes, decreased skin tension (turgor), lethargy, increased heart rate, decreased blood pressure, etc. Supporting examination which can be performed is stool examination (macroscopic and microscopic examination) three times, stool’s culture. The gold standard to diagnose infectious colitis is still by colonoscopy and histopathologic examination (biopsy). The sensitivity and specificity of Infectious Colitis: Diagnosis and Treatment

Amebic Liver Abscess

Purpose: Abstract: Liver abscess is the most common manifestation of systemic amebiasis. Common in endemic areas like Mexico, India, South and East Africa, with increased travel, the incidence is increasing in USA. We present an interesting case of massive amebic liver abscess involving both lobes. Methods: Case Report:48 year old Guyanese male with history of seizure disorder was admitted with the chief compliant of RUQ abdominal pain for one week, with three to four loose stools per day. Pain was worse on coughing and was accompanied by nausea, anorexia and occasional shortness of breath. Patient had a history of alcohol, smoking and was HIV negative. He was taking Dilantin and Ibprofen and had no allergies. Review of systems was unremarkable. On admission patient was afebrile but drowsy with incomprehensible speech. Physical exam was unremarkable except mild RUQ tenderness, with a liver of 2 cm below right costal margin. Stool was positive for occult blood. Lab studies were unremarkable except Hb 11.5, hct 35.2, WBC 42K with 65% toxic bands. LFTs revealed alk phos 277, AST 51, GGT 191, Albumin 2.1, t.bil 1.7, conj. bil 0.8 and LDH 183. On CT was a 16 cm liver mass with surrounding edema, perihepatic fluid and a nonspecific multifocal colitis involving right colon, hepatic flexure, sigmoid and rectum. Patient underwent CT guided drainage of liver abscess, yielding about 800 cc of brown colored thick fluid without evidence of bacteria, mycobacteria, but with presence of ova. Serology was positive for entamoeba histolytica. Subsequent CT revealed decrease in the size of the abscess and patient improved clinically. Colonoscopy revealed ulcerations with overhanging edges, throughout colon, with areas of normal intervening mucosa. Patient was placed on flagyl, zosyn and paramomycin was added as a luminicidal agent. With drainage and treatment, his lab data improved with resolution of colitis and sepsis. Results: Discussion: Ameba is more prevalent in areas of overcrowding and poor sanitation and spread from person to person by fecal oral route. Risk increases with old age, pregnancy, immunosuppression, malnutrition, homosexuality, alcoholism and travel to endemic areas. Cyst ingestion releases trophozoites which adhere to the wall of the large intestine, causing ulceration with subsequent passage into the blood stream. Amebiasis may be acute or chronic, causing symptoms of epigastric pain, jaundice, encephalopathy and sepsis. Abscess is usually solitary involving right lobe with only 10–15% cases revealing multiple small abscesses. Conclusion: Small liver abscess can be successfully treated with antiamebics only, but the larger abscesses, especially those involving the left lobe are more effectively treated with amebicides and aspiration.

Antiamoebic activity of marine sponge Haliclona exigua (Krikpatrick)

The methanol and methanol-chloroform (1:1) extracts of the freshly collected Haliclona exigua showed minumim inhibitory concentration (MIC) of 125 ?g/mL and 250 ?g/mL respectively in in vitro studies, but when both of these were tested in vivo in rats, only methanol-chloroform showed 80% inhibition of trophozoites at the dose of 900 mg/kg body weight against Entameba histolytica. Therefore only methanol-chloroform extract was further fractionated into four fractions (n-hexane, chloroform, n-butanol soluble and n-butanol insoluble fractions). Out of these, only n-hexane and n-butanol soluble fractions showed 80% inhibition of trophozoites at 900 mg/kg dose. Further the chromatography of the n-butanol fraction yielded araguspongin-C which showed promising results at different doses.

Effectiveness of albendazole against viability of entamoeba histolytica in mice and rabbits

Effectiveness of albendazole against viability of entamoeba histolytica in mice and rabbits

Role of Escherichia coli in acute diarrhoea in tribal preschool children of central India

Five hundred and eighty preschool children belonging to tribal areas of Madhya Pradesh were followed up daily for the presence of diarrhoea for a period of 1 year. In all, 1236 episodes of diarrhoea were recorded with an average of 2.13 episodes per child per year. Stool samples were collected during 780 episodes. They were cultured to isolate Escherichia coli as well as non-E. coli enteropathogens. Ten different genes were detected to identify all diarrhoeagenic E. coli using multiplex polymerase chain reaction. Enteroaggregative E. coli was the commonest diarrhoeagenic E. coli and was isolated from 64 children, followed by enteropathogenic E. coli (27), enterotoxigenic E. coli (10) and enterohaemorrhagic E. coli (2). Other enteropathogens detected were bacteria such as Shigella sp, Vibrio cholerae and Salmonella sp, parasites such as Giardia lamblia and Entameba histolytica, and rotavirus. Most of the bacterial pathogens were multi-drug resistant. The study shows that diarrhoeagenic E. coli contribute significantly to the burden of acute diarrhoea in tribal preschool children.

Chronic Diarrhea Caused by Amebic Colitis and Inflammatory Bowel Disease

The diagnosis of intestinal amebiasis is easily established based on colonoscopy, i.e. there is a specific characteristic of ulcer/lesion “discrete flask-shape ulcer” with normal mucosa among the ulcers. However, most patients with amebic colitis have non-specific clinical manifestations and their colonoscopy findings are hardly distinguished from inflammatory bowel disease. In the present case, the patient had a chief complaint of chronic bleeding diarrhea and abdominal pain. The fecal analysis found trophozoites of Entamoeba histolytica. Serology test (sero-amebic) revealed negative result. The colonoscopy examination reveals hyperemic mucosa, edema, and multiple ulcers with various sizes covered with fragile and easily bleed debris, from the rectum to ascending colon, rigid colon, narrowing lumen and tumor/mass appearance on ascending colon. The differential diagnosis was severe amebic colitis and inflammatory bowel disease. Based on the colonoscopy biopsy, we found an active chronic colitis along with dysplasia. The patient received management and treatment of severe amebic colitis and inflammatory bowel disease. Keywords: amebic colitis, bleeding diarrhea, fecal analysis, colonoscopy, biopsy, inflammatory bowel disease

Amoebic infections of the lung and pleura

Pleuropulmonary involvement is the second most common extra-intestinal manifestation of entamoeba histolytica infection after liver abscess. We report 2 cases of pleuropulmonary disease occurring in two men aged 32 and 48 years following an episode of dysentery. Purulent pleural infection was noted in one case. In the other both lung and liver abscesses occurred. The diagnosis was confirmed by strongly positive serology in both cases. Treatment with metronidazole (1.5 g per day) for 15 days combined with pleural drainage led to a satisfactory outcome in both cases.

In vitro activity of azithromycin and dirithromycin against axenic Entamoeba histolytica

In vitro activity of azithromycin and dirithromycin against axenic Entamoeba histolytica

Characterization of entamoeba histolytica antigens in circulating immune complexes in sera of patients with amoebiasis.

Isolated circulating immune complexes (CICs) from sera of patients with amoebiasis were characterized to determine Entamoeba histolytica antigens that participate in the disease process. In total, 116 serum samples were collected before starting anti-amoebic therapy, and their CICs were isolated by differential polyethylene glycol precipitation. The presence of amoeba-specific antigens in CICs was detected by antigen capture enzyme-linked immunosorbent assay (ELISA) and by immunoblot assay. Antigen capture ELISA showed significantly higher optical density (p < 0.001) in all patients with amoebiasis than in the normal healthy controls and patients of non-amoebic hepatic disorder. Immunoblot assay detected amoeba-specific CICs in all 18 patients (100%) with confirmed amoebic liver abscess, 28 (80%) of 35 patients with clinically-suspected amoebic liver abscess, and 18 (78.26%) of 23 patients with amoebic colitis. No patients with non-amoebic hepatic disorders and healthy control subjects had any detectable level of amoebic antigens in CICs. Immunoblot assay revealed E. histolytica antigens of relative molecular masses of 35, 56, 70, and 90 kDa present in CICs of 64 of 76 patients with amoebiasis. The 35-kDa polypeptide was observed in 52 patients (81.25%). The results of the study suggest that the 35-kDa polypeptide antigen can be a diagnostic marker in active amoebiasis.

Examining entamoeba.

A conference on Amebiasis and the Biology of Entamoeba histolytica was held in Agra, India, from 11 to14 February 2002.