Use MRoogle to find plenty of the virus angst threads around here, there might be a thousand or two.
If there would be a virus for Mac OS X, it would be news and on the frontpage of BBC News, albeit a smaller item on there.
There are some malware titles, but you have to manually install them yourself. So if you possess a brain and know how to use it, you should be secure, in Mac OS X and in Windows.