FOREWORD Because the initial discovery of the cause of Rocky Mountain spotted fever was made in the Bitterroot Valley, it is indeed fitting that this conference was held at the Rocky Mountain Laboratories, Hamilton, Montana, the "birthplace" of rickettsiology. Nearly 75 years have elapsed since Dr. Howard Ricketts of the University of Chicago demonstrated conclusively that the tick, Derfnacefztvr aradersorzi, was the vector of the spotted fever agent, which was later named Rickettsia rickettsii in his honor. Early studies on the problem were supported partially by Montana and various universities, but after 1932, when the Rocky Mountain Laboratory became a field station of the U.S. Public Health Service, all research and control program on spotted fever was supported by the federal government. Many of the highlights of this long period of research on rickettsial diseases are listed in the introductory remarks of Dr. John Seal, Deputy Director, National Institute of Allergy and Infectio