I’ve said for years “You NEED AntiVirus software on ANY computer”.  Sure you are less likely (for now) to get a Virus on a Mac, BUT it is defiantly possible.  So get a trusted AV and install it.  Worst case scenario install a free one and periodically scan.  It doesn’t hurt.  Not sure?  Just ask us, we love to help! – R.

“Oh don’t worry,” your uncle said when you were shopping for a new computer. “Macs are virtually virus proof.” Your uncle was wrong.

Source: The World’s First Firmware Worm for Mac Is Here, and It Sounds Scary