BCG Scar Formation and Test Results in Two Generations

Abstract: Introduction: Considering that BCG injection in newborns is part of TB control program in Iran many years ago, we aimed to compare prevalence of childhood BCG vaccination scar with previous study and asses influence of household crowding on TST result.
Aims: Considering that over time there is likely to reduce the immune response, two groups of subjects were selected among young and middle aged.
Methods and Material: This cross sectional study was conducted in Zia Abad of Qazvin (a province of Iran) during year 2008. 261 participants randomly were selected (139 asymp-tomatic children (12-16 y) and 122 adults (40-50 y)). A questionnaire was used to obtain prior histories of BCG vaccination, known exposure to tuberculosis, prior acquired of TB, symptoms of TB disease and household crowding. BCG vaccine scar was ascertained and all participants were tested with 5TU-PPD. Reactions of 10 mm or more were considered positive.
Statistical analysis used: Using student t test, chi square and Fisher’s exact test, the collected data was analyzed.
Results: BCG scar was observed in 78.4% of participant (91.4% children vs. 78.6% adults) which the difference was significant. Twenty three (16.5%) of children and 24 (19.7%) of adults had tuberculin reactivity of ≥10 mm. In children and parent groups, positivity of TST had significant direct association with presence of BCG scar and crowding.
Conclusions: Most vaccinated children had a scar. Our results demonstrate that a TST applied after BCG vaccination usually produces a reaction of <10 mm. In addition, there is a significant relationship between the tuberculin reactivity and both presence of BCG scar and crowding among children and adult groups.