I happened upon this engrossing article from 1999 by Richard Preston about smallpox and I couldn't stop reading. The article details both the history of the virus and also the danger it poses to the human population today. I don't think people like myself who have lived their life blissfully unaware of the real-life dangers of such a virus can truly grasp the horror of such a virus if it were to have an outbreak.
Even though smallpox was responsible for a number of deaths in the 20th century that would be equal to about the entire current population of the United States - I truly do think that the word smallpox has any meaning to the modern mind. The word smallpox has as much meaning to the modern mind as the word codpiece.
Richard Preston is the master of virus outbreak stories. His book The Hot Zone: A Terrifying True Story remains the scariest book I ever read. Stephen King has nothing to compare with the horror Preston describes. The phrase "crashing and bleeding out" still gives me the shivers. I heartily recommend both the article linked above and the book Hot Zone.