Apple OS X users can catch the first real virus for Apple's OS X platform as easily as Windows users can catch the Bagle virus, according to anti-virus firm Sophos.

Leap-A or Oompa-Loompa, which was discovered in the wild earlier this week, spreads itself through Apple's iChat instant messaging application. However, in order to become infected, the Mac user must decompress the malicious file then run it, which is exactly what Windows users had to do in order to become infected by the Bagle virus.

Sean Richmond, senior technical consultant at Sophos, told ZDNet Australia that Leap-A has been misreported as a Trojan when it should actually be called a virus.

"It is not a Trojan. It can spread under its own power it is no more than [windows users] had to do for the Bagle worm, which came in a password protected zip file... People would unzip [Bagle] and run the executable inside," said Richmond.

Leap-A is the first piece of OS X malware to be discovered 'in the wild'. In late 2004, a piece of malware dubbed Renepo or Opener by security firms, proved that the Mac platform was not being completely ignored by cybercriminals.

Richmond admits that Leap-A is not a big risk but he said Mac users should see it as a wake up call.

"We have a low prevalence but it has been seen in the wild, whereas renepo, which did a lot to decrease OS X security but was never seen in the wild. This is out there rather than being an oddity," said Richmond.