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 μg Mycobacterium avium sensitin RS10 or 0.1 μg Mycobacterium scrofulaceum sensitin RS95. None of the 762 children had any known exposure to tuberculosis. A total of 8.8% reacted with an induration (⩾ 3 mm to PPD RT23 while 2% reacted with ⩾ 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 ⩾ 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.