i read here that there is a trojan in mac~

No, that's a trojan, not a virus.

A virus self-replicates on itself. A Trojan needs to run to actually do something. As I can see the trojan is inside an application archive called FixTunes.

And besides, no one said macs are fool-proof. No Operating Systems are. It's just that Macs are harder to "attack".

Besides, another thing to consider is the virus/trojan a Mac virus or trojan?

Sometimes a mac can have a lot of redundant virii/trojans sitting inside your mac which are windows viruses/trojans who do nothing but sit pretty inside your mac due to file sharing with windows users, emails etc. They don't attack Macs but you can scan and remove them.

So before you spread unnecessary FUD (Fear, Uncertainty and Doubt), do your own research and understand the state of Mac Security before screaming "OMIGOSH GOT VIRUS!! GOT VIRUS" (ok, a bit exaggerated, but you get my point).