In fact there is Bitcoin viruses. Or at least I can think they can be called that way. There is two. The first one is the copy-paster changer, putting hacker's address when you copy-paste the address into your wallet. And the virus that send your bitcoins to the hacker address automatically.
I disagree. You cannot consider or treat the copy-paste changer or whatever do you call it, as a Bitcoin virus. It does not ring the bell or it does not have the appeal. It is just a simple trojan or a malware that changes the copied address on the clipboard. A real Bitcoin virus for my point of view is a virus that will target and attack the Bitcoin technology itself and not an individual user.