EVIDENCE OF PREVIOUS INFECTION WITH MYCOBACTERIUM-AVIUM-MYCOBACTERIUM-INTRACELLULARE COMPLEX AMONG HEALTHY-SUBJECTS - AN INTERNATIONAL STUDY OF DOMINANT MYCOBACTERIAL SKIN-TEST REACTIONS

Skin tests with 0.1 mL of intermediate-strength Mycobacterium tubercul osis purified protein derivative (PPD) and 0.1 mL of Mycobacterium avi um sensitin were conducted on 484 healthy subjects from diverse geogra phic sites. Reactions of greater-than-or-equal-to 5 mm to one antigen that exceeded the reaction to the other by greater-than-or-equal-to 3 mm were considered M. avium- or PPD-dominant. PPD-dominant reactions w ere more frequent at sites where routine Bacille Calmette-Guerin immun ization is done or where there are high rates of tuberculosis: New Ham pshire, 2%; Boston, 7%; Finland, 14%; Trinidad, 26%; and Kenya, 28%. H owever, rates of M. avium-dominant reactions ranged from 7% to 12% at all sites. Analysis of dominant reactions based on a more stringent 10 -mm minimum reaction size showed similar trends. These data suggest th at exposure to MAC is similar in developed and developing countries bu t that broad mycobacterial immunity is greater in developing countries and may contribute to the lower rates of disseminated MAC infections in AIDS in these areas.