[Skin reaction test using PPD-B].

Inapparent infection caused by Mycobacterium avium-M. intracellulare complex was examined in healthy persons by skin reaction tests using purified protein derivatives of M. intracellulare ATCC 19530 (PPD-B). Skin reaction to PPD-B was evaluated as positive, as it was for PPDs, when the diameter of the reaction (redness) was 10 mm or more, and it was evaluated as significantly positive when the reaction was the same or larger than that to PPDs. Examination of 379 volunteers (ages 18-53, one female only) from the Kaitaichi Station, Ground Self-Defence Force gave the following positive and significantly positive rates by age respectively: 12.8% and 10.3% for ages 18-19, 25.8% and 9.0% for ages 20-29, 39.7% and 12.8% for ages 30-39, and 51.2% and 15.5% for ages 40-53, and the rates were 32.7% and 11.1% for all ages combined. The positive rates to PPDs, on the other hand, were 33.3% for ages 18-19, 65.7% for ages 20-29, 91.0% for ages 30-39, and 95.2% for ages 40-53, and the rate was 74.1% for all ages combined. The PPD-B positive rate increased with age from 12.8% at 18-19 years of age to 51.2%, but the significantly positive rate showed no significant increase. Evaluation to PPD-B and PPDs were both positive, because of the difficulty of determining clearly whether the cause was M. tuberculosis and M. avium complex infection or cross reaction of skin reaction to PPDs and PPD-B.