ABSTRACT
Using guinea-pigs infected experimentally with human tubercle bacilli and rabbits infected experimentally with bovine tubercle bacilli, a series of studies was made to ascertain whether or not diphtheria toxoid would influence the expected course of the resultant tuberculosis. Seventhy guinea-pigs and ten rabbits were used. The administration of toxoid in relation to the inoculation of the animals with the infective agent varied in the different studies. In two groups of guinea-pigs, treatment was started the same day that the animals were infected. In another group treatment was delayed for four weeks after the animals had been infected, and in another group the guinea-pigs had received two doses of toxoid one month apart before being infected. The rabbits received the first dose of toxoid simultaneously with the infective organism. The initial dose of toxoid for the guinea-pigs was 0.1 cc. Subsequent doses were administered every two weeks, with each succeeding dose 0.05cc. greater than the preceding dose. The initial dose for rabbits was 0.2cc. This was increased by 0.1cc. at each succeeding injection, whch was at two week intervals. The toxoid was injected intramuscularly. The experiments continued until all of the animals had died, which was somewhat in excess of seven months. All of the animals died of tuberculosis, and there were no significant differences between the treated and the untreated froups. The results indicate quite convincingly that under the conditions of the experiments diphtheria toxoid failed to exert any significant deterrent effect on tuberculosis experimentally induced in guine´-pigs and in rabbits.