Do I Need an Antivirusprogramm program like Avira
DDo I Need an Antivirusprogramm program like Avira for mac bou
MacBook Pro (13-inch Mid 2009), OS X Yosemite
No, anti-virus programs are not needed with Macs, just use some common sense in visiting websites. Mac OS X has builtin protection and a firewall that works very well. Avoid almost all anti-virus software, but especially the commercial stuff from Norton and McAfee - those are horrible drains on the the system performance and extremely difficult to remove.
Do not get MacKeeper or any cleaning programs, they are mainly malware.
Go to Thomas Reed's site http://www.thesafemac.com for more tips. Tom is a regular contributor on here and a very good security person. His AdwareMedic is a gem.