Well, I have brought up my own pet theory on midi-chlorians before:

http://originaltrilogy.com/forum/topic.cfm/Do-the-Star-Wars-movies-contain-evidence-that-Lucas-makes-it-up-as-he-goes/post/739465/#TopicPost739465

In this scenario, midi-chlorians can be genetically modified so that they can be repurposed as microscopic Force-wielders, put to whatever purpose the modifier wants them for. You want them to suck a person dry of the Force, eventually killing them? It's done. You want to do the complete opposite and restore a sick person to full health? No sweat. You want to induce asexual reproduction in a human woman? It's a snap.

Of course, depending on how much you want to hold to TCW, I don't know how this theory can be applied. The way midi-chlorians were depicted in the final episodes of the show strongly suggest they can't be reduced to simple Force-parasites.