Strongyloidiasis in humans: diagnostic efficacy of four conventional methods and real-time polymerase chain reaction.

INTRODUCTION: Strongyloides stercoralis is an intestinal parasitic nematode that causes hyperinfection and/or a dissemination syndrome in hosts, which is often difficult to diagnose. This study aims to compare the diagnostic efficacy of four conventional methods used to diagnose strongyloidiasis with real-time polymerase chain reaction (qPCR) to detect S. stercoralis in fecal samples. METHODS: We analyzed 143 fecal samples collected from Colombian regions with varying degrees of risk for intestinal infections caused by S. stercoralis to assess the validity, performance, overall efficiency, and concordance of the qPCR using a direct stool test, modified Ritchie concentration technique, agar plate culture, and Harada-Mori technique as reference tests. RESULTS: While four fecal samples were positive for S. stercoralis using conventional methods, 32 were positive via qPCR. The diagnostic sensitivity of the qPCR was 75% [95% confidence interval (CI): 20.07-100%], whereas its specificity, negative predictive value, negative likelihood ratio, and Youden's J index were 78.42% (95% CI: 71.22-85.62%), 99.09% (95% CI: 96.86-100%), 0.32 (95% CI: 0.06-1.74), and 0.53, respectively. In addition, the estimated kappa index between the qPCR and the conventional methods was 0.12 (95% CI: -0.020-0.26). CONCLUSIONS: The diagnostic sensitivity of qPCR to detect strongyloidiasis is analogous to that of conventional parasitology methods, with an additional advantage of being capable of identifying the parasite DNA at low sample concentrations.

Strongyloidiasis in humans: diagnostic efficacy of four conventional methods and real-time polymerase chain reaction

Abstract INTRODUCTION: Strongyloides stercoralis is an intestinal parasitic nematode that causes hyperinfection and/or a dissemination syndrome in hosts, which is often difficult to diagnose. This study aims to compare the diagnostic efficacy of four conventional methods used to diagnose strongyloidiasis with real-time polymerase chain reaction (qPCR) to detect S. stercoralis in fecal samples. METHODS: We analyzed 143 fecal samples collected from Colombian regions with varying degrees of risk for intestinal infections caused by S. stercoralis to assess the validity, performance, overall efficiency, and concordance of the qPCR using a direct stool test, modified Ritchie concentration technique, agar plate culture, and Harada-Mori technique as reference tests. RESULTS While four fecal samples were positive for S. stercoralis using conventional methods, 32 were positive via qPCR. The diagnostic sensitivity of the qPCR was 75% [95% confidence interval (CI): 20.07-100%], whereas its specificity, negative predictive value, negative likelihood ratio, and Youden's J index were 78.42% (95% CI: 71.22-85.62%), 99.09% (95% CI: 96.86-100%), 0.32 (95% CI: 0.06-1.74), and 0.53, respectively. In addition, the estimated kappa index between the qPCR and the conventional methods was 0.12 (95% CI: -0.020-0.26). CONCLUSIONS: The diagnostic sensitivity of qPCR to detect strongyloidiasis is analogous to that of conventional parasitology methods, with an additional advantage of being capable of identifying the parasite DNA at low sample concentrations.

Procedure optimization for concentration and detection of protozoa and helminths in great volumes of water / Optimización del procedimiento para la concentración y detección de protozoos y helmintos en grandes volúmenes de agua

Feces-contaminated water is a vehicle of transmission of potentially pathogenic microorganisms responsible for illnesses that represent main causes of death worldwide. A protocol for detection of intestinal parasites in great volumes of water was optimized. It includes: membrane filtration, mechanical agitation with detergent, centrifugation, chemical concentration with Mini Parasep® and microscopic examination. From samples of feces-contaminated water containing parasitic forms, a total recovery percentage of 85.7 percent of parasites was achieved after tests. This procedure provides a useful alternative method that could be subjected to validation as a routine methodology in the diagnosis of microbiological water quality(AU)

El agua contaminada con heces es un vehículo de transmisión de microorganismos potencialmente patógenos causantes de enfermedades que constituyen causas principales de muerte a nivel mundial. Se optimizó un protocolo para la detección de parásitos intestinales en grandes volúmenes de agua. Este incluye: filtración por membrana, agitación mecánica con detergente, centrifugación, concentración química con Mini Parasep® y examen microscópico.En muestras de agua contaminada con heces que contenían formas parasitarias, se obtuvo un porcentaje de recuperación total del 85.7 por ciento de estas formas después de aplicar el protocolo. El procedimiento constituye un método alternativo que podría someterse a validación como metodología habitual para el diagnóstico de la calidad microbiológica del agua(AU)

Prevalencia de parasitosis intestinal, anemia y desnutrición en niños de un resguardo indígena Nasa, Cauca, Colombia, 2015 / Prevalence of intestinal parasites, anemia and malnutrition among the children of a Nasa indigenous reservation, Cauca-Colombia, 2015 / Incidência de parasitose intestinal, anemia e desnutrição em crianças na reserva indígena de Nasa, Cauca-Colômbia, 2015

Resumen Objetivo: determinar la prevalencia de parasitosis intestinal, anemia y desnutrición en niños de un resguardo indígena Nasa de Caldono, en el departamento del Cauca, y su distribución según variables clínicas, sociodemográficas y de infraestructura sanitaria. Metodología: estudio transversal con fuente de información primaria. La muestra de estudio estuvo formada por 62 niños, a quienes se les hicieron evaluación parasitológica en materia fecal, mediciones antropométricas para evaluar el estado nutricional y determinar la prevalencia de diferentes tipos de desnutrición y medición de hemoglobina para establecer la anemia. La descripción del grupo se realizó con medidas de resumen para la edad y frecuencias para las demás variables, se calculó la prevalencia de los tres eventos (parasitosis, desnutrición, anemia) y se exploró su asociación con variables independientes mediante pruebas de hipótesis. Se usó el programa SPSS 22.0. Resultados: se encontró una prevalencia de parasitosis intestinal de 95,2%, anemia de 21,0% y desnutrición crónica de 35,5%. A pesar de no hallar asociación estadística con las condiciones sociodemográficas y sanitarias, se encontró elevada frecuencia de factores de riesgo para los tres eventos, como la baja escolaridad de los padres, baja disponibilidad de acueducto y alcantarillado, y una elevada morbilidad sentida. Conclusión: la comunidad indígena evaluada presentó altas prevalencias de parasitosis intestinal, anemia y desnutrición, lo que representa implicaciones prácticas para la orientación de los programas de salud indígena; la exploración de asociaciones requiere estudios con mayor tamaño de muestra que garanticen una mayor potencia estadística.

Abstract Objective: to determine the prevalence of intestinal parasitosis, anemia and malnutrition among children of a Nasa indigenous reservation from Caldono in the Colombian department of Cauca, and their distribution according to clinical, sociodemographic and healthcareinfrastructure variables. Methodology: a cross-sectional study with a primary source of information. Sixty-two children were evaluated for intestinal parasites via stool analysis. Similarly, anthropometric measurements were used to assess nutritional status and determine the prevalence of various types of malnutrition. Likewise, the presence of anemia was determined by measuring hemoglobin levels. The group was described using summary measures for age and frequency measures for the other variables. Prevalence was calculated for intestinal parasites, anemia and malnutrition, and its association with independent variables was explored using hypothesis testing. The program SPSS 22.0 was used in this study. Results: the prevalence values were: 95.2% for intestinal parasites, 21% for anemia and 35.5% for chronic malnutrition. Although there was no statistical association with sociodemographic and health conditions in the study group, a high frequency of risk factors for intestinal parasites, anemia and malnutrition was found. These factors were: parents with low schooling levels, low availability of aqueducts and sewerage and high perceived morbidity. Conclusion: The evaluated indigenous community had a high prevalence of intestinal parasites, anemia and malnutrition. This has practical implications for the direction that healthcare programs targeting indigenous populations should take. Exploring the associations requires further studies with larger sample sizes which guarantee greater statistical power.

Resumo Introdução: As parasitoses intestinais humanas são consideradas um grave problema de saúde pública em países de baixa renda; além disso, elas apresentam vínculos clínicos e epidemiológicos com anemia e desnutrição, especialmente em comunidades indígenas. Objetivo: Determinar a incidência de parasitose intestinal, anemia e desnutrição em crianças da reserva indígena de Nasa de Caldono, no Departamento de Cauca, e sua distribuição segundo variáveis clínicas, sociodemográficas e de infraestrutura sanitária. Metodologia: Estudo transversal com fonte de informação primária. A mostra de estudo esteve formada por 62 crianças, nas quais foram realizadas avaliações parasitológicas em material fecal, medições antropométricas para que se fosse avaliado o estado nutricional e determinada a incidência de diferentes tipos de desnutrição, e medição de hemoglobina para que se determinasse a anemia. A descrição do grupo realizou-se com medidas de síntese por idade e frequências; para as demais variáveis, calculou-se a incidência dos três eventos (parasitoses, desnutrição, anemia), e explorou-se sua associação com as variáveis independentes mediante verificação da hipótese. Utilizou-se o programa SPSS 22.0. Resultados: Verificou-se uma incidência de parasitose intestinal de 95,2%, anemia de 21,0% , e desnutrição crônica de 35,5%. Apesar de não ter sido comprovada uma associação estatística entre as condições sociodemográficas e sanitárias, verificou-se uma elevada frequência de fatores de risco para os três eventos, como a baixa escolaridade dos pais, baixa disponibilidade de água tratada e saneamento, assim como uma elevada morbidade manifestada. Conclusão: A comunidade indígena avaliada apresentou altas incidências de parasitose intestinal, anemia e desnutrição, o que representa implicações práticas para a orientação dos programas de saúde indígena; a exploração de associações requer estudos com maior grandeza de amostra que garantam um maior poder estatístico.