Avirulent Strains of Pasteurella Pestis

Abstract

When Haffkine developed his plague prophylactic in 1896, many bacteriologists believed that the problem of plague prevention was at least partly solved. At the turn of the century, however, some workers1,2'3 expressed dissatisfaction with the heat-killed preparation and proceeded to investigate the possibility and practicability of a true live vaccine. In their opinion, the Haffkine prophylactic and other preparations containing only killed Pasteurella pestis and its products of metabolism and disintegration were unsatisfactory because they failed to give a high degree of protection to inoculated human beings, and particularly because it was impossible to immunize guinea pigs with them. Since the latter had been found highly susceptible to experimental inoculation with plague bacilli, there was a strong argument in favor of a live vaccine which could, in very minute doses, completely protect these animals against plague infection instead of just slightly enhancing their resistance to it, as did the killed prophylactics. The controversy over killed or live plague vaccine has continued for the past 4 decades up to the present day. The advocates of live-plague vaccine have received a powerful stimulus