Complex sentence: Pneumonic plague is the only form of plague that has person-to-person transmission which occurs during droplet-respiration, and humans can become infected when handling tissue or body fluids of a plague-infected animal.
Split into simpler sentences: Pneumonic plague is the only form of plague that has person-to-person transmission which occurs during droplet-respiration. And humans can become infected when handling tissue or body fluids of a plague-infected animal.