Are there viruses in the Linux world?

[Neil Moore-Smith]

I never hear of viruses in the Linux (or Unix generally) world. There used 
to be the Internet Worm, but mostly, the only attacks I hear about are 
security exploits, holes in sendmail etc.

Are there any Linux viruses? I would have thought that the availability of 
the source code would have been a real boon to the sad individuals who 
write these things. Are there anti-virus tools?

application/ms-tnef