Tuberculin response of Sri Lankan children after BCG vaccination at birth

Abstract

A total of 740 healthy children aged between 3 months and 11 years who had received BCG vaccination in the first month of life were Mantoux tested in Sri Lanka. Despite 97 % having a visible scar following vaccination, 80 % showed Tuberculin anergy (0–1 mm). Those without a scar showed no response. There was no correlation between scar size and the Mantoux response.A low mean Mantoux reaction was seen at all ages: 3.5 mm at 3 months, 3.2 mm at 18 months, 1.8 mm at 5–7 years and 1.9 mm at 9–11 years. A significant waning of the Mantoux reaction occurred at 5–7 years but there was no significant change at 9–11 years. Children who had received routine revaccination at 10 years, having received the first at birth, had a significantly higher mean Mantoux reaction (9.6 mm) when tested 3 months after revaccination. In 90 bacteriologically proven tuberculous patients, there was a significantly increased Mantoux reaction compared to all other groups. 1 T.U. PPD RT 23 (with tween 80) was used in all instances for Mantoux testing.The present study shows that routine BCG vaccination at birth, using a reduced dose of 0.05 ml, is unlikely to interfere subsequently with the diagnostic value of the Mantoux test. However, revaccination at 10 years may do so.