Bodhi Zazhen, Ubuntu Forums administrator, had this to say about virus detection on Linux:
In my experience with antivirus applications on Linux is that:
1. For the most part they generate more false positives then true virus detedction.
2. For all the hype generated by those trying to push antivirus on Linux, the linux scanners do not seem to be as good at detection as Windows antivirus nor do they have as many features.
IMO running antivirus scanners is not part of Linux security, see :
Ubuntu Security - Ubuntu Forums
Master Foo and the Nervous Novice