These large furry growths on computer monitors and heat registers are seasonal here, happening only in the colder months. They come and go without intervention on our part, and we're only mildly allergic to them as long as we vacuum more frequently.
If there is a sudden increase in the number or size of the growths, we'll have to do something about them. Meanwhile we just take precautions that they won't be spread, though we've heard reports of spontaneous appearance in several other houses on our street. Probably carried by airborne spores.
We'll keep an eye on it.