You also have to take into consideration that you're only asking about miners. Most, if not all, of the miners are in pools and the pools are, more often than not, in large industrial mining facilities, for Bitcoin. So to have an attack, virus, on a miner you could, theoretically, take down an asic or two before the staff at these facilities figure out what's going on. But you won't take down the whole pool. Once they do, they'll get new asics and get rid of the infected ones. As for Bitcoins themselves, I don't see a virus infecting a Bitcoin and then distributing among the populace. But I could be wrong there.
