Science Fiction.
Hugo Award Nominee for Best Novel (1985), Philip K. Dick Award Nominee (1985), Compton Crook Award (1985)
Mass market paperback
Candidia Maria Smith-Foster, an eleven-year-old girl, is unaware that she's a Homo post hominem, mankind's next evolutionary step.

With international relations rapidly deteriorating, Candy's father, publicly a small-town pathologist but secretly a government biowarfare expert, is called to Washington. Candy remains at home.

The following day a worldwide attack, featuring a bionuclear plague, wipes out virtually all of humanity (i.e., Homo sapiens). With her pet bird Terry, she survives the attack in the shelter beneath their house. Emerging three months later, she learns of her genetic heritage and sets off to search for others of her kind.

I have the paperbacks of Emergence & Threshold.