Influence of Bacille Calmette-Guérin on tuberculin skin testing in Venezuelan Amerindians in high tuberculosis burden areas.

INTRODUCTION: Extraordinarily high tuberculosis (TB) prevalence rates have been reported in Venezuelan Amerindians. Amerindian populations often live in geographically isolated villages where they receive little medical attention and live under precarious sanitary conditions. TB prevalence varies by ethnicity and geographic location and is generally higher in Amerindians than in non-indigenous (Creole) people. METHODOLOGY: Between January 1, 1998 and December 31, 2009, the tuberculin skin test (TST) was administered during field operations to 9,538 Amerindian and Creole people between 0 and 94 years of age living in Venezuela. In 6,979 individuals (73%), Bacille Calmette-Guérin (BCG) vaccination status, age, and ethnicity were recorded. Univariate and multivariate analyses were performed to determine the influence of previous BCG vaccination, age, and ethnicity on TST outcomes. RESULTS: Age, ethnicity, and the number of BCG vaccinations administered each had a significant influence on TST outcomes (p < 0.001). The influence of BCG vaccination on TST outcomes varied by ethnicity and was only significant in children aged between 0 and 3 years. CONCLUSIONS: The utility of TST in the diagnosis of TB infection in high TB burden settings with widespread BCG vaccination should be evaluated locally and individually as this depends on ethnicity, age, and the number of BCG vaccinations administered. In Venezuelan children 4 years of age and older, the TST remains a useful tool for the detection of TB infection, independent of BCG vaccination status.

Calidad bacteriológica del agua del río Cataniapo, municipio Atures, estado Amazonas, Venezuela / Sanitary quality of the hydrographic basin of the Cataniapo river, Atures municipality, Amazonas state, Venezuela

La calidad bacteriológica del agua es importante por cuanto es uno de los parámetros usados para la clasificación de las fuentes de agua. En este trabajo se logró determinar la calidad bacteriológica de muestras de agua del río Cataniapo, en 11 puntos distribuidos a lo largo de su cuenca media, baja, y alta, mediante muestreos mensuales realizados, durante julio a diciembre de 2005. Se determinó el Número Más Probable (NMP) de coliformes totales y coliformes fecales presentes en el agua, mediante la técnica de fermentación en tubos múltiples. Se aislaron e identificaron enterobacterias presentes en las muestras de agua de las diferentes estaciones de la cuenca del río Cataniapo. Las menores densidades de coliformes totales y fecales, se evidenciaron durante el período de lluvia: julio - septiembre y las máximas durante el período de sequía: octubre - diciembre. Los resultados del análisis de varianza doble mostraron que existen diferencias significativas entre meses y estaciones para coliformes totales, y diferencias significativas entre estaciones para coliformes fecales; encontrándose que los puntos 1 y 3 de la cuenca baja, presentaron las densidades más altas para este grupo bacteriano, sobrepasando el límite permitido para aguas clasificadas para contacto humano, parcial ó total. La especie Escherichia coli fue identificada con mayor frecuencia en todas las estaciones.

The bacteriologiocal quality of water is an important parameter used for the classification of water supplies. We analyzed the bacteriological quality of the water from the Cataniapo river at 11 stations distributed along the low, middle and high basin, by monthly sampling conducted from July till December 2005. The total and fecal coliforms in the water where determined by the Most Probable Number (MPN) method, using the Multiple Tube Fermentation technique. The Enterobacteriaceae were isolated and identified in samples of water from different stations at Cataniapo river. The lowest density of total and fecal coliforms were evident during the rainy season (July to September) and the highest during the drought period (October to December). The quantity of total coliforms differed significantly between the different stations at the Cataniapo river and amongst the different months sampled, while for fecal coliforms we found only significant differences only between the stations. We also found that the points 1 and 3 of the lower basin, had the highest densities for fecal coliforms, exceeding the stablished limit for human contact (total or partial). The Escherichia coli species was identified as the most frequent amongst all stations.

Mycobacterium tuberculosis ecology in Venezuela: epidemiologic correlates of common spoligotypes and a large clonal cluster defined by MIRU-VNTR-24.

BACKGROUND: Tuberculosis remains an endemic public health problem, but the ecology of the TB strains prevalent, and their transmission, can vary by country and by region. We sought to investigate the prevalence of Mycobacterium tuberculosis strains in different regions of Venezuela. A previous study identified the most prevalent strains in Venezuela but did not show geographical distribution nor identify clonal genotypes. To better understand local strain ecology, we used spoligotyping to analyze 1298 M. tuberculosis strains isolated in Venezuela from 1997 to 2006, predominantly from two large urban centers and two geographically distinct indigenous areas, and then studied a subgroup with MIRU-VNTR 24 loci. RESULTS: The distribution of spoligotype families is similar to that previously reported for Venezuela and other South American countries: LAM 53%, T 10%, Haarlem 5%, S 1.9%, X 1.2%, Beijing 0.4%, and EAI 0.2%. The six most common shared types (SIT's 17, 93, 605, 42, 53, 20) accounted for 49% of the isolates and were the most common in almost all regions, but only a minority were clustered by MIRU-VNTR 24. One exception was the third most frequent overall, SIT 605, which is the most common spoligotype in the state of Carabobo but infrequent in other regions. MIRU-VNTR homogeneity suggests it is a clonal group of strains and was named the "Carabobo" genotype. Epidemiologic comparisons showed that patients with SIT 17 were younger and more likely to have had specimens positive for Acid Fast Bacilli on microscopy, and patients with SIT 53 were older and more commonly smear negative. Female TB patients tended to be younger than male patients. Patients from the high incidence, indigenous population in Delta Amacuro state were younger and had a nearly equal male:female distribution. CONCLUSION: Six SIT's cause nearly half of the cases of tuberculosis in Venezuela and dominate in nearly all regions. Strains with SIT 17, the most common pattern overall may be more actively transmitted and SIT 53 strains may be less virulent and associated with reactivation of past infections in older patients. In contrast to other common spoligotypes, strains with SIT 605 form a clonal group centered in the state of Carabobo.