Howard Haggard was a professor of applied physiology at Yale University and the author of several books, including Devils, Drugs, and Doctors: The Story and Science of Healing from Medicine-Man to Doctor. Medical Mystery.
"Epidemics of pestilencestill rage unchecked in countries less civilized than our own, but such epidemics do not arouse concern for our own safety. It is taken for granted by most people that we are immune or that from some law of geographic distribution these diseases cannot extend to our country. In reality we are no more immune than were the people of the Middle Ages. There are few diseases against which geographic barriers are effective. It is only modern preventative measures that keep these diseases out."
— Devils, Drugs, and Doctors: The Story and Science of Healing from Medicine-Man to Doctor