Sensitivity to sensitins and tuberculin in Swedish children. II. A study of preschool children.

Non-BCG-vaccinated preschool children (4 or 5 years of age) were simultaneously tested on separate arms with a 2 IU PPD RT23 and 0.1 microgram Mycobacterium avium sensitin RS10 or 0.1 microgram Mycobacterium scrofulaceum sensitin RS95. None of the 762 children had any known exposure to tuberculosis. A total of 8.8% reacted with an induration (greater than or equal to 3 mm to PPD RT23 while 2% reacted with greater than or equal to 6 mm. Half the children were tested with M. avium sensitin: 18.9 and 7.8% reacted when 3 and 6 mm cut-off points, respectively, were taken. The remaining children were tested with M. scrofulaceum sensitin: 18.4 and 6.3%, respectively, reacted. In a previous study of schoolchildren aged 8 or 9 years, reactions to sensitins were considerably more frequent. Thus, sensitisation by atypical mycobacteria seems to increase from the preschool to the early school age. This finding probably reflects a continuous exposure of the children to atypical mycobacteria from various sources. The preschool children with a reaction to PPD RT23 greater than or equal to 6 mm were examined and chest X-rays were performed. All children were healthy but one child had enlarged lymph nodes in the mediastinum and abdomen. It cannot be excluded that these pathological findings were caused by atypical mycobacteria.