One of the Four Horsemen of the Apocalypse in the Book of Revelation, Pestilence has menaced humankind from the beginning. Moderns assume that medical science can deal with any such threat but, even today, there is no cure for yellow fever, Ebola, Marburg, smallpox, West Nile, polio, equine encephalitis, herpes, or SARS. Though supportive medical treatment can improve the odds of survival in some cases, there is very little surge capacity in our medical establishment to handle a major outbreak. In the absence of any treatment, mortality rates soar as high as 90-95% for Ebola, inhalation anthrax, and pneumonic bubonic plague; 70% for SARS and yellow fever. New and deadly diseases may evolve anywhere in the world. Today's globe-trotting culture guarantees that, if loosed into the population in one location, it will be spread in a matter of hours to the rest of the world.