Apple's brand image is no viruses. That's crucial to their marketing. That is why this mindset is common among mac users. But if you follow technology news you will find that there are waves of malware and viruses that target osx.
It's true that there is malware for OS X. However "waves of malware" might be hyperbole.
Lets have a closer look at what there is and how afraid we should be.
There is a list of all of the existing malware for OS X here:
The Safe Mac : Mac Malware Guide
There are a handful of pieces of malware for the Mac. The majority of those are now extinct. Compare that to the *well over a million* pieces of malware for Windows:
BBC NEWS | Technology | Computer viruses hit one million
Sophos has reported that they see over 95,000 new threats for Windows *every day*!!!
Top Ten Tips to Avoid the Regulatory Auditor's Wrath - Data Threat Detection and Prevention | Sophos Security Topics - Virus, Malware, Web, Antivirus and Social Media Security Trends - Cloud Antivirus, Endpoint, UTM, Encryption, Mobile, DLP, Server, See item #5.
So, if you are basing your fears about Macintosh malware on experience having to do with Windows, you are comparing Apples to Oranges. (No pun intended.)
Now, have a look to the far left of each of those pieces of malware for the Mac at:
The Safe Mac : Mac Malware Guide
There you will see the "threat level" of each. You will notice that none of them have a "high" threat level, and most have a threat level of "none" or "very low."
There is only one that gets as high as "moderate." That threat, Pintsized, can easily be avoided as it is Java-based. Most modern Macs don't even have Java installed, and for those that do you can protect yourself by simply turning Java off in your browser.
Now, we've established that there is just about no threat from existing malware. But there is still a threat, as small as it is. Should we be afraid? No, because ever since OS X 10.6 (we are now at OS X 10.9) the Mac OS has included anti-virus software
The Safe Mac » Mac Malware Guide : How does Mac OS X protect me?
Mountain Lion: Hands on with Gatekeeper | Macworld
Every modern Mac which has been kept updated with Apple's security updates is safe from all existing malware.
Let me also point out that all of the major Mac Web browsers have software built-in (licensed from Google), that keeps users from visiting malicious Web sites where they might pick up malware, called "Safe Browsing":
Safe Browsing ? Transparency Report ? Google
This is also frequently updated.
So, what malware is it, exactly, that Mac users need to be afraid of?