Diatomaceous Earth. It's a very fine powdery sand made of silica and shell fragments that can be a natural filter like charcoal. In certain situations it is thought to be useful internally to help a body filter gut toxins or viruses. Up until recently it was mostly used externally in a variety of products as well as organic pesticides (it's good against soft-bodied creatures like slugs), but food grade DE has been used as a clarifier in wine and beer.

It wouldn't hurt to give it a try if you knew you had an enterovirus, but the thing about enteroviruses is that it's hard to know you have one and you'd have to know you had it to start treating it in the illness phase.