Tularemia Vaccine Study: I. Intracutaneous Challenge

The frequency with which Pasteurella tularensis infects hunters of rabbits and laboratory workers studying this microorganism makes vaccination of these persons desirable. However, the protective value of available nonviable vaccines is not certain. Studies on this point have been conducted by Foshay et al. 1 and Kadull et al. 2 The ideal method of evaluating a vaccine intended for protection of humans is to challenge volunteers, both vaccinated and nonvaccinated, with a reproducible known infective dose of the disease-producing agent. A study in a small vaccinated group challenged by a known infective dose can provide more specific information in a shorter time than by assembling a much larger number in a study in which vaccinated persons are "exposed" accidentally in varying degree or not at all. Pasteurella tularensis offers certain advantages in such a critical study employing human challenge with viable microorganisms. A broad base of preliminary experience is provided