Wouldn't she die if the Wolbachia got on her? I mean, she's got parasites keeping her alive. If those stop reproducing, her bodily ecosystem would vanish and she would slowly die, right?
Maybe. That'd be an interesting reason. I can't recall if the game explicitly said anything to that effect, though.
Quiet has an interesting situation. Her vital functions are maintained by one group of parasites. She's given special powers (superhuman speed, resilient skin, optical camouflage) by a second group of parasites. And she's a carrier for a third group of parasites: the English-language strain of the vocal cord parasites.
Normally, once activated, the English-language strain would copulate in her throat, the larvae consuming her lungs as a result. This would kill her. However, her lungs are no longer functional, and she doesn't need them to survive. In theory, the larvae could eat whatever is left of her lungs and it wouldn't kill her.
After a period of time, though, she would be a walking bioweapon. She hightailed it out of there before she could infect anyone, but the question remains: Is she still out there in the desert? Will she put a bullet to her brain or succumb to dehydration, or will she survive and simply avoid civilization?