A librarian at College of Santa Fe Fogelson Library recently found a small, yellowed envelope tucked between the pages of an 1888 book on Civil War medicine. The envelope was labeled "scabs from vaccination of W.B. Yarrington's children." This inscription could only mean smallpox, a deadly infection that was eradicated a generation ago.

Although the live smallpox virus currently resides in two laboratories in the world, it is considered a potentially devastating weapon for bioterrorists. The envelope, now stored at a freezer at the Centers for Disease Control and Prevention in Atlanta, could yield live smallpox. If a live virus is obtained, not only would scientists learn more about the plague, they also would gain insight into the evolution of smallpox vaccine in the United States.