title: The significance of positive Mantoux reactions in BCG-vaccinated children.
abstract: As the interpretation of tuberculin skin tests is controversial in subjects who have received BCG vaccine, we administered Mantoux tests to 2588 randomly selected Saudi children aged 5-13, 1945 of whom had been vaccinated with BCG at birth and 643 were unvaccinated. Only 7.8% of the BCG-vaccinated children were Mantoux positive (greater than or equal to 10 mm induration) at the age of 5 years, which was not significantly different from the unvaccinated children. The tuberculin sensitivity rose more steeply with age in the BCG-vaccinated than the unvaccinated children so that the difference between both groups became statistically significant in those aged 12 and 13 (20% versus 3.9%, 15.5% versus 4.1% respectively). These findings support the previously expressed theoretical postulates that BCG-vaccinated subjects display an increased ability to respond immunologically to encounters with environmental mycobacteria. In communities with low prevalence of environmental mycobacteria, this would result in a slow but persistent rise of skin reactivity to tuberculin which, if given time, will become greater than that of unvaccinated subjects.
authors.affiliation: Department of Medicine, College of Medicine, King Saud University, Riyadh, Saudi Arabia.
authors.forename: F A
authors.initials: FA
authors.lastname: al-Kassimi
authors.forename: A K
authors.initials: AK
authors.lastname: Abdullah
authors.forename: I O
authors.initials: IO
authors.lastname: al-Orainey
authors.forename: A B
authors.initials: AB
authors.lastname: Benar
authors.forename: M S
authors.initials: MS
authors.lastname: al-Hajjaj
authors.forename: S
authors.initials: S
authors.lastname: al-Majed
authors.forename: A
authors.initials: A
authors.lastname: al-Wazzan
mesh_terms: D000293:Adolescent; D001500:BCG Vaccine; D002648:Child; D002675:Child, Preschool; D006801:Humans; D006968:Hypersensitivity, Delayed; D012867:Skin / Q000276:immunology; D013997:Time Factors; D014374:Tuberculin Test; D014376:Tuberculosis / Q000276:immunology / Q000517:prevention & control*
chemical_list: D001500:BCG Vaccine