Trying to remember the title of a book


I'm wondering if anybody can help me rember the title of an alternate history Book I read a long time ago.

I believe the cold war went hot, and it was fought with bioweapons. A plague wiped out most of the Caucasian people in the Americas, and the continent was re-taken by the Native Americans.

Has anybody read this book? Can you tell me what it was called?
I'm probably way off, but it sounds a little by like the Star Trek episode known as the Omega Glory.