Never heard of the author do unaware of the genre (s)he works in, other than you pointing out, animals, possibly high intelligence due to evolution and a post appocolyptic war where the animals mutated into Intelligent beings.
That being the case, I would suggest a scientist dying of radiation poisoning being infested with headlice his daughter brought home from school. Touching moments as he holds her lifeless body to him and the live make their way to a live host. Feeding on his blood, they also drink in his intelligence as their DNA mixes with his. In short time, they evolve into the size of field mice, an evolution of a decade. They study the tech of the time, especially the nano technology suited for their size. Along the way, they can create mind control for larger animals, using a plot device much like Heinlein's puppet masters story.
Hope this helps. Remember, every idea has to have a starting point and you have to admit, this is somewhat original. How many works of fiction do you know where the protagonists are head lice?