Studies of vaccination of persons in close contact with leprosy patients in Argentina.

A total of 670 adults living or working with leprosy patients, were examined for a BCG vaccination scar, and skin-tested with four new tuberculins. Based on the results 513 were vaccinated, 65 with Bacille de Calmette et Guérin (BCG) alone, 66 with BCG plus killed Mycobacterium vaccae and 382 with killed M. vaccae alone. Skin-testing was repeated 2-3 years later on 344 subjects, when all three vaccines were found to have been highly successful in increasing responses to Tuberculin and Leprosin A (p < 0.0005) with increased immune recognition of common and species-specific antigens. Mean diameters of induration to each skin-test were greatest in recipients of BCG alone (p < 0.05), which suggests that better immuno-regulation occurs after receiving vaccines that incorporate M. vaccae. The results suggest 10(8) M. vaccae alone might prove a valuable future vaccine, which would not require selective pre-vaccination procedures.