Mac OS X has been the target of a little virus that is a proof-of-concept to demonstrate that the operating system is vulnerable to hackers.

Symantec classifies it as a level-one, “very low” threat, because it doesn’t deposit any sort of malware on the system other than it itself. Its job is to self replicate in whatever folder the Mac owner is using.

Called OSX.Macarena, it’s only known to have infected about 50 computers. Symantec and other security researchers have called it a “wake up call” for Mac owners, who should be protecting their systems with anti-virus software just like Windows-based computer owners have to. According to the Symantec advisory, to remove it Mac users must use anti-virus software to clean it.

There aren’t many viruses known that infect Mac systems, although last year the first one was found being transmitted through the iChat instant messaging system.