The Mantoux and Mitsuda reactions in hamsters and guinea-pigs before and after vaccination with BCG.

While investigations were in progress elsewhere in Venezuela on the modifications of the reactions to tuberculin and lepromin after BeG vaccination in groups of humans in leprosy-endemic foci (2). parallel experiments were made with hamsters and guinea-pigs at the Cabo Blanco Leprosarium. The results are reported here. The problem of lepromin sensitization in animals has attracted the attention of leprologists repeatedly. since Rodriguez in 1938 (5) reported the application of the test to a number of different animals and found that dogs, rabbits and a goat reacted positively. Wade (.) condueted thorough experiments with doga at Culion in 1941, and one of his conclusions was that time is a more important factor in the production of positivity than the quantity of antigen injected. Chaussinand, In his book La Upre ('), affirms that guinea-pigs normally do not reaet positively to lepromin, an experience which differs from ours with the strain ot albinos kept at Cabo Blanco. Olmos Calltro (4) studied the effect of BCG vaccination in causing positive reactions to lepromin in guinea-pig!!. In animals which he considered to be normally nonreactors he observed that the degree ot positiVity increased with incrC4se of the dose of BCG. He ascribes more importance to the late than to the early or Fernandez reaction, and he does not consider repeated inoculation with BCG to be necessary to bring about either. Hadler (.) studied the immunologic re:aponse of tuberculin-negative guinea-piga to heat-killed BCG and to lepromin and found that both mycobacteria evoke histologically similar skin reactions, but that the enzymatic elimination of the leprosy • bacillus Is much slower tha" is the case with the tubercle bacillus (BCG) .