Examen coproparasitológico en niños: comparación de resultados obtenidos por dos métodos en dos instituciones de Santafé de Bogotá, D.C.

Abstract

This survey was carried out in order to compare the frequency of intestinal parasite detection by direct wet film in stool specimens from children done simultaneously at the Hospital Infantil Lorencita Villegas de Santos (HILVS) and at the Parasitology Department of the Instituto Nacional de Salud (INS). The usefulness of tao methods for the detection of intestinal parasites in the same institution (INS) was compared - direct wet examination and concentration by the formalin-ethersedimentation technique, Four hundred and eighty seven faecal samples of children were taken randomly from 2,954 received at HILVS during six months. A fraction of each sample was sent from the hospital to INS for its parasitological examination. Later on, 305 out of 398 clinical records belonging to children whose stools had been examined every day during three consecutive days, were retrospectively reviewed to describe some demographic factors and the possible signs and symptoms which necessitated the stool examination. The signs and symptoms found by the revision of the clinical records did not necessarily correspond to those associated with intestinal parasites. I No parasites were detected in two hundred and seventy seven (56.9%) samples. Of the two hundred and ten (43.1%) positive samples, pathogenic parasites were found in ninety three (19.1%) The concordance between the examination of faeces at HILVS and INS was measured by the Kappa index. The strength of agreement was almost perfect for Giardia lamblia, substantial for Trichomonas hominis, moderate for lodamoeba bütschliiand Entamoeba coli, fair for Endolimax nana, Trichuris trichiura and Blastocystis hominis, slight for Entamoeba histolytica and poor for Entamoeba hartmanni. The sensitivity and specificity values obtained from direct wet examination and the forrnalin-ether sedimentation technique showed a greater identification of parasites by the concentration method. Nevertheless, there is overlapping between the upper limit of the confidence interval for the direct wet mount and the lower limit of the confidence interval for the formalin-ether sedimentation technique. It is therefore not possible to conclude that the sensitivity of the concentration method is better than that of the direct wet mount. The overall and specific prevalences of parasites were lower than those reported by the National morbidity survey on intestinal parasitism. The study emphasizes the following topics: 1) the need to set up guidelines and precise indications for ordering faecal examinations in order to avoid loss of time and money; 2) the importance of the accuracy of the diagnostic methods, and 3) the need to establish precise morphological criteria for the correct identification of parasites at any laboratory.