Stephen G. Baum, M.D., is Distinguished Professor Emeritus of Medicine, Microbiology & Immunology and Senior Advisor, Medical Scientist Training Program, at the Albert Einstein College of Medicine, Bronx, New York. Previously, he was Chairman of the Department of Medicine at Beth Israel Medical Center in New York. He has conducted extensive research on DNA tumor viruses (adenovirus and SV40). A former president of the New York Society for Infectious Diseases, Dr. Baum has written chapters on adenovirus, mumps, aseptic meningitis, mycoplasma, and viral pneumonia for several textbooks.