CORRELATION OF TUBERCULIN INDURATION WITH THE NUMBER OF BACILLUS-CALMETTE-GUERIN VACCINES

In developing countries with a higher prevalence of tuberculous infect ion, usually more than one Bacillus Calmette-Guerin (BCG) vaccine is r ecommended, Revaccination can considerably alter the tuberculin skin t est response and the diagnosis of tuberculous infection, In this study to assess the relationship between the number of BCC; vaccinations an d tuberculin skin reactions, 3548 children (ages 6 to 12 years) from 7 elementary schools were given 5 tuberculin units of purified protein derivative, and results were compared taking vaccination status into a ccount, Forty-seven children were excluded from the study, Mean purifi ed protein derivative induration size at 72 hours was 3.2 +/- 3.9 mm w ith no BCG scar (n = 1518), 6.3 +/- 7.8 mm with 1 scar (n = 1513), 10. 7 +/- 6.2 mm with 2 scars (n = 433) and 14.8 +/- 4.3 mm with 3 scars ( n = 37), In children with no scar the 90th percentile values of the si ze of the purified protein derivative induration were 10 mm. The 90th percentile values of children with one, two and three scars were 15, 1 7.5 and 20 mm, respectively. We suggest that tuberculin skin test resp onses be evaluated with regard to the number of previous BCG vaccinati ons.