The popular image of Biological Warfare engages our attention through references to exotic illness that cause rapid death, and are extremely contagious. The Ebola or Marburg Hemorrhagic Virus is typical of those that are mentioned on CDC’s special pathogen branch lists. Descriptions of civilization-killing diseases in the popular media are similar: consider, for example, the book Oryx and Crake, the film 28 Days After, The Stand by Stephen King. Other books that I have read include The White Plague by Frank Herbert and Earth Abides by George R. Stewart, and they all have a similarly rapid plague that sweeps through and destabilizes/destroys civilization.
However that isn’t the way a really serious biological incident would likely unfold, because any fast moving disease would also admit the possibility of isolation/quarantine/travel restrictions which could stop its spread, and because it existence would be quickly identified. The really dangerous disease would be something that is very quickly spread, but which have a very long prodrome, that is the time between infection and the point at which the clinical features of the disease become apparent.
