BOZEMAN, Montana — Grim prognostications of pestilence are as old as the Book of Revelation, but they have not gone out of style or been rendered moot. Plague is a tribulation that science, technology and social engineering haven’t fixed. In the mid-1960s, some public health officials imagined that antibiotics and other modern therapies would enable us to “close the book” on infectious diseases and so make it possible to focus on noncommunicable afflictions, like heart attack, diabetes and stroke. But that optimism was mistaken.