Tuberculin reactivity in a pediatric population with high BCG vaccination coverage
Abstract:SETTING: The tuberculin skin test (TST) is often included in diagnostic algorithms for tuberculosis (TB) in children. TST interpretation, however, may be complicated by prior Bacillus Calmette-Guérin (BCG) vaccination. We assessed the prevalence of and risk factors for positive TST reactions in children 3 to 60 months of age in Botswana, a country with high TB rates and BCG coverage of over 90%.
METHODS: A multi-stage cluster survey was conducted in one rural and three urban districts. Data collected included demographic characteristics, nutritional indices, vaccination status, and prior TB exposure. Mantoux TSTs were administered and induration measured at 48–72 hours.
RESULTS: Of 821 children identified, 783 had TSTs placed and read. Of the 759 children with vaccination cards, 755 (99.5%) had received BCG vaccine. Seventy-nine per cent of children had 0 mm induration, 7% had ≥10 mm induration (‘positive’ TST), and 2% had ≥15 mm. A positive TST was associated with reported contact with any person with active TB (odds ratio [OR] 1.9; 95% confidence interval [CI] 1.02–3.6), or a mother (OR 5.1; 95% CI 2.1–12.4) or aunt (OR 5.3; 95% CI 2.0–14.0) with active TB. TSTs ≥5 mm (but not ≥10 mm) were associated with presence of a BCG scar. Positive reactions were not associated with age, time since BCG vaccination, clinical signs or symptoms of TB, nutritional status, crowding, or recent measles or polio immunization.
CONCLUSION: The TST remains useful in identifying children with tuberculous infection in this setting of high TB prevalence and extensive BCG coverage.
Document Type: Regular Paper
Affiliations: 1: Division of TB Elimination, National Centers for HIV/AIDS, STD and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, USA 2: Division of TB Elimination, National Centers for HIV/AIDS, STD and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, USA; and BOTUSA TB Project, Gaborone, Botswana 3: Communicable Diseases Section, Botswana Ministry of Health, Gaborone, Botswana
Publication date: 1999-01-01
The International Journal of Tuberculosis and Lung Disease publishes articles on all aspects of lung health, including public health-related issues such as training programmes, cost-benefit analysis, legislation, epidemiology, intervention studies and health systems research. The IJTLD is dedicated to the continuing education of physicians and health personnel and the dissemination of information on tuberculosis and lung health world-wide.
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