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Anaemia in pre-school children in an urban area.
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An unusual case of acute amoebiasis.
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Clinical trial methodology in intestinal parasitic diseases.
The high prevalence of intestinal parasitic infections as an index of underdevelopment, especially in tropical countries, is related to poverty, poor housing, lack of sanitation, malnutrition, and ignorance. The effects are lowered work capacity, physical and mental retardation, leading to recurrences and exacerbations of the parasitism and malnutrition. The most prevalent parasites, methods of detection by specific tests in patients in clinical trials involving antiparasitic drugs are dealt with. How and by whom investigations of new drugs should be undertaken, the need for a basic knowledge of parasitology and techniques of the discipline, of biostatistics, and use of such controls as randomized allotment to treatment groups, placebo administration, and double-blind assessments are emphasized. The justification for undertaking an evaluation of an antiparasitic drug is predicated on the demonstration of safety in exhaustive in vitro and animal studies and of the drug's potential superiority as to efficacy and lower incidence of unwanted side effects, as compared with existing agents. Tolerance and dose-range studies should be conducted in male adult hospitalized patients under close supervision. The evaluation of amebicides in clinical trials, as well as of anthelmintics, is considered in terms of differentiation and reproductive habits of specific causative agents and tests for detecting their elimination to determine improvement under drug therapy. The problem of reinfection, particuarly of nonhospitalized patients under the adverse conditions of life, is stressed.
Identification of the galactose-adherence lectin epitopes of Entamoeba histolytica that stimulate tumor necrosis factor-alpha production by macrophages.
The 170-kDa subunit of the galactose-adherence lectin (Gal-lectin) of Entamoeba histolytica mediates adherence to human colonic mucins and intestinal epithelium as a prerequisite to amebic invasion. The Gal-lectin is an immunodominant molecule and a protective antigen in the gerbil model of amebiasis. Tumor necrosis factor alpha (TNF-alpha) produced by activated macrophages enhances nitric oxide-dependent cytotoxicity in host defense against E. histolytica. The purpose of this study was to identify the Gal-lectin epitopes which stimulate TNF-alpha production by macrophages. Murine bone marrow-derived macrophages (BMMs) exposed to Gal-lectin (100-500 ng/ml) stimulated stable expression of TNF-alpha mRNA (8-fold increase) and TNF-alpha production similar to that of lipopolysaccharide-stimulated cells (100 ng/ml). Polyclonal anti-lectin serum specifically inhibited TNF-alpha mRNA induction in response to the Gal-lectin but not to lipopolysaccharide. Anti-lectin monoclonal antibodies 8C12, H85 and 1G7, which recognize nonoverlapping epitopes of the cysteine-rich region of the 170-kDa heavy subunit, inhibited both amebic adherence to mammalian cells and Gal-lectin-stimulated TNF-alpha mRNA expression by BMMs,but monoclonal antibody 7F4 did neither. As these inhibitory antibodies map to amino acids 596-1082 of the 170-kDa Gal-lectin, our results have identified the functional region that mediates amebic adherence and TNF-alpha mRNA induction in BMMMs; thus, this region of the Gal-lectin is a subunit vaccine candidate.
The experimental transmission of human intestinal protozoan parasites. III. Attempts to transmit Endamoeba coli and Giardia lamblia cysts by flies.
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The experimental transmission of human intestinal protozoan parasites. IV. Attempts to transmit Endamoeba coli and Giardia lamblia cysts by water.
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[Malignant colonic amebiasis (on a case surgically treated with success)].
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[Functional symptomatology of gastroduodenitis in amebiasis and lambliasis patients].
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[Investigation of intestinal parasites in residents of the Kayseri Karpuzsekisi basin].
In this study, we collected stool and cellophane tape samples from residents in four villages located in the Kayseri-Karpuzsekisi basin in order to investigate the distribution of intestinal parasites. A total of 240 samples collected from Hanyeri (40), Sariküklü (20), Dokuzpinar (80) and Karpuzsekisi (120) were investigated. The parasites detected were as follows: Blastocystis hominis, 82 (34.16%); Enterobius vermicularis, 37 (15.41%); Entamoeba coli 26, (10.83%); Entamoeba hartmanni, 10 (4.16%); Giardia intestinalis, 7 (2.91%); Endolimax nana, 5 (2.08%); Entamoeba histolytica/E. dispar, 4 (1.66%); and Taenia saginata, 1 (0.41%).
Fulminating necrotizing amebic colitis with perforation: case report and review.
A seriously ill patient with diffuse abdominal tenderness of unknown cause is described. The diagnosis proved to be fulminating necrotizing amebic colitis with perforation. This case report serves as a reminder that amebiasis may occur in patients who have not been outside Canada, that it may readily be confused with other types of inflammatory bowel disease, and that particular care should be taken in obtaining a history of exposure. Before inflammatory bowel disease is diagnosed not only should the usual diagnostic tests such as stool examination and mucosal biopsy be done, but also serologic testing for amebiasis should be carried out.
Thoracic amebiasis.
Pleuropulmonary amebiasis is the common and pericardial amebiasis the rare form of thoracic amebiasis. Low socioeconomic conditions, malnutrition, chronic alcoholism, and ASD with left to right shunt are contributing factors to the development of pulmonary amebiasis. Although no age is exempt, it commonly occurs in patients aged 20 to 40 years, with an adult male to female ratio of 10:1. Children rarely develop thoracic amebiasis: when it does occur there is an equal sex distribution. The infection usually spreads to the lungs by extension of an amebic liver abscess. Infection may pass to the thorax directly from the primary intestinal lesion through hematogenous spread, however. Lymphatic spread is one possible route. Inhalation of dust containing cysts and aspiration of cysts or trophozoites of E histolytica in the lungs are some other hypothetical routes. The lung is the second most common extraintestinal site of amebic involvement after the liver. Usually the lower lobe, and sometimes the middle lobe of the right lung, are affected, but it may affect any lobe of the lungs. The patient develops fever and right upper quadrant pain that is referred to the tip of the right shoulder or in between the scapula. Hemophtysis is common. The diagnosis of thoracic amebiasis is suggested by the combination of an elevated hemidiaphragm (usually right), hepatomegaly, pleural effusion, and involvement of the right lung base in the form of haziness and obliteration of costophrenic and costodiaphragmatic angles. Infection is usually extended to the thorax by perforation of a hepatic abscess through the diaphragm and across an obliterated pleural space, producing pulmonary consolidation, abscesses, or broncho-hepatic fistula. Empyema develops when a liver abscess ruptures into the pleural space. Rarely, a posterior amebic liver abscess can burst into the inferior vena cava and develop an embolism of the inferior vena cava and thromboembolic disease of the lungs with congestive cardiac failure or corpulmonale. Diagnosis by finding E histolytica in stool specimens is of limited value. In a limited number of cases amebae might be found in aspirated pus or expectorated sputum. "Anchovy sauce-like" pus or sputum may be found. Presence of bile in sputum indicates that the pus is of liver origin. Serological tests are of immense value in diagnosis. Liver enzymes are usually normal and neutrophilic leucocytosis may or may not be found. ESR is invariably elevated. Anti-amebic antibodies can be detected by ELISA, IFAT, and IHA. Amebic antigen can be detected from serum and pus by ELISA. Detection of Entamoeba DNA in pus or sputum may be a sensitive and specific method. Pleuropulmonary amebiasis is easily confused with other illnesses and is treated as pulmonary TB, bacterial lung abscesses, and carcinoma of the lung. A single drug regimen with metronidazole with supportive therapy usually cures patients without residual anomalies. Aspiration of pus from empyema thoracis may be needed for confirmation and therapeutic purposes. The pericardium is usually involved by direct extension from the amebic abscess of the left lobe of the liver, sometimes from the right lobe of the liver, and rarely from the lungs or pleura. An initial accumulation of serous fluid due to reactive pericarditis followed by intrapericardial rupture may develop either (1) acute onset of severe symptoms with chest pain, dyspnea, and cardiac tamponade, shock, and death, or (2) progressive effusion with thoracic cage pain, progressive dyspnea, and fever. Chest radiograph, ultrasound examination, and CT scan usually confirm the presence of a liver abscess in continuity with the pericardium and fluid within the pericardial sac with or without the fistulous tract. Echocardiography may demonstrate fluid in the pericardial cavity. Patients should be cared for in the ICU and ambecides should be started without delay. Pericardiocentesis usually confirms the diagnosis and improves the general condition of the patient. Aspiration of the accumulated fluid should be performed urgently in cardiac tamponade; repeated aspiration may be needed. Surgical drainage should be done if needed. Acanthamoeba, a free-living ameba, may also infect the lungs in the form of pulmonary nodular infiltration and pulmonary edema in association with amebic meningoencephalitis in immunocompromised patients. It usually spreads to the meninges of the brain by way of the blood from its primary lesion in the lung or skin. Early diagnosis and institution of treatment may be life saving for these patients. A literature review shows that HIV/AIDS patients are not prone to infection with E histolytica. It is now clear that there are an increasing number of HIV-seropositive patients among amebic liver abscess patients, however, which suggests that although the incidence of intestinal infection is not high among HIV-seropositive or AIDS patients they are more susceptible to an invasive form of the disease.
Protection in a gerbil model of amebiasis by oral immunization with Salmonella expressing the galactose/N-acetyl D-galactosamine inhibitable lectin of Entamoeba histolytica.
Infection with the enteric parasite Entamoeba histolytica can result in colitis and dysentery as well as abscesses at extra-intestinal sites. An effective vaccine must be able to protect against both mucosal and systemic disease. In this study an attenuated Salmonella strain that expressed a portion of the GalNAc lectin of E, histolytica was used to orally immunize gerbils. Animals were challenged by intrahepatic injection of amebic trophozoites. A significant decrease in size of amebic liver abscesses was observed in orally immunized animals. Oral immunization with a Salmonella-based vaccine was as effective as systemic immunization for protection against systemic challenge.
Common and uncommon parasitic infections in the United States.
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Case records of the Massachusetts General Hospital. Weekly clinicopathological exercises. Case 18-1990. A 58-year-old man with hematochezia and a lesion of the cecum.
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Single-dose and short course regimens of metronidazole in the treatment of amoebiasis in Malaysia.
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Invasive amebiasis in naturally infected New World and Old World monkeys with and without clinical disease.
Histopathological preparations of cecum and colon from monkeys naturally infected with invasive Entamoeba histolytica were examined to determine the distribution of amebae in the tissues and the types of lesions, if any, associated with them. Infections were studied in 3 New World species (10 Callicebus moloch, 1 C. torquatus, and 2 Aotus trivirgatus) and 3 Old World species (8 Macaca mulatta, 6 Erythrocebus patas, and 1 Cercopithecus aethiops). Amebiasis was recorded as the principal or a contributing cause of death of all of the 13 New World monkeys and in 6 of the 15 Old World monkeys; amebiasis was detected in the rest of the monkeys only after tissues were re-examined specifically for amebae. Amebae causing no apparent damage were found in the lamina propriae, mainly at the muscularis mucosae. Most frequent were colonies or aggregates of amebae in the crypts between the epithelium and basement membrane, causing either no evident necrosis or changes ranging from necrosis and disarrangement of adjacent cells to complete destruction of the epithelium and reduction of the cells to pyknotic bodies. A lesion interpreted as possibly characteristic of carrier-state invasive amebiasis was destruction of the epithelium in patches of mucosal crypts, not leading to ulceration. Uncommon but present in both New and Old World monkeys were typical areas of surface erosion and classical flask-shaped ulcers. The observations show that in some species of Old World monkeys amebiasis can be invasive without causing clinical disease.