Clay's ark - Octavia E. Butler

In an alternate America marked by volatile class warfare, Blake Maslin is traveling with his teenage twin daughters when their car is ambushed. Their attackers appear sickly yet possess inhuman strength, and they transport Blake's family to an isolated compound. There, the three captives discover that the compound's residents have a highly contagious alien disease that has mutated their DNA to make them powerful, dangerous, and compelled to infect others. If Blake and his daughters do not escape, they will be infected with a virus that will either kill them outright or transform them into outcasts whose very existence is a threat to the world around them.