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

Abstract

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 CalmetteGuérin (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.

Agreement between QuantiFERON®-TB Gold In-Tube and the tuberculin skin test and predictors of positive test results in Warao Amerindian pediatric tuberculosis contacts

“…This indigenous population resides in the Orinoco River Delta, where they live in wooden houses raised on stilts along the Orinoco River banks. Tuberculin purified protein derivative used for TST testing is not widely available in the Warao communities, although surveys using TST testing have been performed [22]. The diagnosis of TB disease and the subsequent initiation of TB treatment occurs through the Orinoco Delta Department of the Venezuelan National TB Program situated in the hospital in Tucupita, the state capital city of the Orinoco Delta on the mainland.…”

Tuberculin skin tests following Bacille Calmette Guerin vaccination in Africa: a protocol for systematic review and meta-analysis

“…Vaccination with live viruses such as live-measles, may cause false-negative tuberculin reactions [ 9 ] while anergy can occur in individuals with impaired cellular immune function such as those with severe malnutrition or immune-deficiency diseases. Also, the technique of BCG administration, dose, the age at which vaccine was administered, gender, socioeconomic status, degree of TB burden in the community, the people´s genetic background, ethnicity, the manufacturer of the vaccine, the interval between vaccination and testing, have been reported to affect the risk and degree of a reactive PPD tuberculin skin test following BCG vaccination [ 10 - 16 ]. Notwithstanding these confounding effects of BCG on PPD tuberculin test readings, exposure to TB through contacts is more likely to increase positive PPD [ 17 , 18 ], hence, individuals from countries with a high or moderate incidence of TB are more likely to have reactive PPDs than those from countries of low incidence.…”