Viruses - so we are told - replicate by virtue of invading previously healthy cells. But there are no negative feedbacks in the system - only the positive feedback of the (assumed) immune system. The more pathogens there are the more exhausted and vulnerable the immune system becomes. This means that once the virus has gained traction in the body then the virus will necessarily experience a runaway effect (ie organism death).
In the absence of a negative feedback the *only* way to stop a runaway effect is with a discontinuity. A deus ex Machina (magic).
Clearly the imposition of a discontinuity in the model renders said model trivial.
To put it another way: *if* there was a pathogenic virus then, in the absence of magic, *no* organism could exist.
This is why I told you to watch Fantasia. It's a perfect illustration of the mathematical problem when there are no negative feedbacks in a biological (reproducing/replicating) model. The *only* solution (obviously no solution at all) is sorcery.
