Here's the door to your body, see? And these are oversized novelty germs. That's influenza, that's bronchitis,

and this cute little cuddle-bug is pancreatic cancer. Here's what happens when they all try to get through the door at once. [tries to cram a bunch through the model door. The "germs" get stuck] Woo-woo-woo-woo-woo-woo-woo! Move it, chowderhead! We call it, "Three Stooges Syndrome."
Burns: So what you're saying is, I'm indestructible!
Doctor: Oh, no, no, in fact, even slight breeze could --
Burns: Indestructible.

http://www.wired.com/wiredscience/2011/03/virus-therapy-hiv/

Sounds like a good idea. If you can't beat them join them. Can't stop the spread of aids, so create a virus that attacks the aids virus whenever it comes into contact with it. It won't cure those people who have it, but if it can arrest its spread, it's a great start.