Virus warning messages

The message is a scam. Close the offending page, and avoid sites that are involved in such bogus advertising tactics.

Avoid phishing emails, fake 'virus' alerts, phony support calls, and other scams - Apple Support

Nope, no myth. You can't get something that doesn't exist. There no actual viruses for the Mac OS, either.

Don't believe the many web sites who claim to list Mac viruses. Every single one they mention is a Trojan.

Viruses self replicate with no user interaction. Trojans can't get on your Mac unless you put it there. You may not know you're installing one, but it still requires an action by the user for it to happen.

The iPad cannot get viruses.

You’re quite welcome.

It's true :)