Dr. Walker, Director of the Center for Biodefense and Emerging Infectious Diseases, has fostered investigations of arboviral infections, emerging viral hemorrhagic fevers, and rickettsioses in state-of-the-art BSL-3 and BSL-4 facilities., n, nHe has elucidated mechanisms of immunity to Rickettsia and Ehrlichia, and developed animal models for rickettsioses, ehrlichioses, and scrub typhus. He contributed to the discovery, characterization, and,or epidemiology of several emerging infectious diseases. His efforts have enhanced rickettsiology in China, Sicily, Mexico, Brazil, Peru and Cameroon. His commitment to high quality up-to-date knowledge is exemplified in Tropical Infectious Diseases: Principles, Pathogens, and Practice. He has served on the Armed Forces Epidemiology Board, Defense Health Board, and National Research Council Standing Committee on Biodefense and is Associate Editor of Emerging Infectious Diseases and Nature Vaccines.