You just posted in the mac osx section. Do you have a osx virus scanner. There are no known viruses that affect OSX afaik.

Besides, I think you may find that warning now happens when downlding with your browsers meaning it's probably due to the recent OSX security update.

An AV or spyware utility is up to the users to employ themselves since people will have their prefered ones. And maintaining a virus descriptions database is a full-time business.