The Contribution of the Social Environment to Host Resistance

I count myself honored indeed to be included among those who have been chosen to present this, the Wade Hampton Frost Lecture. Unlike my predecessors in this series, I never had the privilege of knowing or meeting Dr. Frost, although of course I know many of his illustrious students. I do claim one unique experience, however; I read his collected papers when practicing in South Africa before I had ever heard of the word epidemiology, much less knew what it meant. In a real sense, then, those papers were my introduction to the whole field, and for this I must thank my very wise chief, Dr. Sidney L. Kark, who introduced me to the papers, particularly the section on tuberculosis. The thinking displayed in those articles opened my eyes to a new world and provided an opportunity to begin to understand what up until then had been to me a totally mysterious phenomenon, the explosive epidemic of tuberculosis I was witnessing in the African population for whom I was providing care. Perhaps, though, of all the words Frost wrote, the ones that have made the most impression on me have been his often quoted introduction to the reprinting of John Snow's papers (1) which starts, "Epidemiology at any given time is something more than the total of its established facts. It includes their orderly arrangement into chains of inference which extend beyond the bounds of direct observation." It is this "orderly arrangement into chains of inference" which intrigues me and which I