[Etiologic, clinical and socio-democratic characteristics of acute diarrhea in Venezuela]. / Características etiológicas, clínicas y sociodemográficas de la diarrea aguda en Venezuela.

In four cities of Venezuela a study was carried out to evaluate the epidemiological, clinical, and etiological characteristics of acute diarrhea in children under 5 years of age. The study was done between June 1993 and May 1995 and involved children who were seen in a hospital, 2,552 with diarrhea and 793 controls. The Fisher exact test was used for the statistical analysis of the results. Rotaviruses were the most important agents, both in terms of their frequency (30%) and their association with dehydration (58%). Following in importance were Campylobacter spp. (13%) and Escherichia coli classical O serogroups (9%), but their association with diarrhea was only statistically significant among children less than 3 months old, a fact that is particularly important from the standpoint of treatment. The importance of age was confirmed as a determining factor in the prevalence and severity of diarrhea.

[Morphology of Blastocystis hominis in feces and evaluation of parasitological methods]. / La morfologia del Blastocystis hominis en las heces y evaluación de métodos parasitológicos.

A study of the morphology of Blastocystis hominis in stool in ninety-four cases humans is described as central body, ameba and granular form were found as previously described. In addition a "Globulose" form as a variation of granular form is first described. The central body form (96.8%) was the most abundant form. Three parasitological methods as direct microscopical examination sample with saline solution 0.85%, lugol, Sudan III, stained with Quensel, Iron hematoxylin and culture are evaluated to detection the Blastocystis hominis forms. Our results show that the direct microscopical examination (saline solution 0.85%, lugol, Sudan III, stained with Quensel) is the most sensitive and specific method than culture. The identification of Blastocystis hominis in stool difficult due to the diversity of shapes and size, which generate confusion with other intestinal protozoa and host cells.

Immunocytochemical detection of Entamoeba histolytica.

Human anti-Entamoeba histolytica immunoglobulin was used to detect Entamoeba histolytica in 74 positive samples from several different sources, using an indirect immunoperoxidase method. In 73 samples, the protozoan was easily identified. Trophozoites and cysts of all cultured Entamoeba strains examined were strongly stained, and as few as 3 trophozoites per microscope slide could be detected. In addition, 51 negative control samples were also tested and non-specific reactions were not observed. These preliminary results show that this method is both sensitive and specific, and can easily detect trophozoites and cysts of different E. histolytica strains.

Surface properties of Entamoeba: increased rates of human erythrocyte phagocytosis in pathogenic strains.

The assertion that ingestion of human erythrocytes is restricted to invasive strains of Entamoeba histolytica has not been evaluated previously by comparative studies. In this report we describe the in vitro ingestion of human erythrocytes by pathogenic and nonpathogenic Entamoeba. Microscopic evaluation of erythrophagocytosis by eight different Entamoeba grown in culture revealed that strains of E. histolytica isolated from cases of human dysentery show a much higher rate of erythrocyte ingestion than nonpathogenic strains. However, all strains are able to phagocytize erythrocytes. The extremely high rate of phagocytic activity shown by pathogenic E. histolytica could be one of the properties related to the pathogenicity of this parasitic protozoan.

[Phagocytosis of human erythrocytes by Entamoeba histolytica. Quantitative study]. / Fagocitosis de eritrocitos humanos por Entamoeba histolytica. Estudio cuantitativo.

The degree of eythrophagocytosis of two recently isolated strains of E. histolytica was measured by microscopic examination. Amebas isolated from a patient with amebic rectocolitis (strain HM22:IMSS, monoxenic) ingested human red blood cells faster and in larger numbers than trophozoites isolated from an asymptomatic carrier (HM27:IMSS, monoxenic). The results suggest that an increased rate of phagocytosis could be one of the surface properties characteristic of the invasive strains of E. histolytica.

[Culture and establishment of new Mexican Strains of Entamoeba histolytica]. / Cultivo y establecimiento de nuevas cepas mexicanas de Entamoeba histolytica.

Mixed and monoxenic cultures of rectal exudates from three patients with amebiasis of colon, and of feces from three asymptomatic carriers of Entamoeba histolytica obtained after administration of a saline cathartic, and from a case of exudate of the perianal cutaneous lesion border produced by this parasite, were done. The culture media used were for: mixed culture, Boeck and Drbohlav modified culture and, for monoxenic culture, Diamond's monophasic TP-S-1 medium without vitamin mixture and using bovine serum. In order to inhibit the bacterial growth in the mixed culture, streptomycin sulphate and pencillin G were used. In order to eliminate the bacterial flora kanamicin sulphate, chloramphenicol, gentamycin and disodic carbenicillin were added. Mixed cultures of seven strains of Entamoeba histolytica were obtained: HM22:IMSS, HM23:IMSS, HM24:IMSS, HM26:IMSS, HM27:IMSS, HM28:IMSS y HM29:IMSS, and monoxenic culture with Bacteroids symbiosus of the strains HM22:IMSS and HM27:IMSS, with a previous adaptation in mixed culture. The adaptation of HM26:IMSS strain in monoxenic culture was obtained by means of direct seeding of the rectal exudate with Fusobacterium symbiosus.

[Intestinal amebiasis in children. I. Etiological study of colonic lesions of the rectosigmoid colon]. / La amebiasis intestinal en el niño. I. Estudio etiológico de las lesiones de colon rectosigmoideo.

A total of 253 children from two months to 12 years old, who had diarrheic or dysenteric syndromes, were studied from the rectosigmoidoscopic and parasitologic points of view. In addition, 112 and 20 of these patients were also studied bacteriologically and virologically, respectively. Only in 28 patients torphozoites of Entamoeba histolytica were found by means of direct microscopic examination, staining techniques and amoebal cultures. Enteropathogenic bacteria were isolated in 41 of the 112 cases examined. No viral particles were detected in the 20 cases studied. From the discussion of these results, the conclusion is reached that the rectosigmoidal mucusal alterations which have been currently considered as suggesting amoebal lessions are not characteristic of invasive intestinal amebiasis in children.