What is 5. a numbered question? I haven't heard of that. Does Linux have viruses, yes to a certain degree. Most have limited affects on Linux and Unix which is the base operating system of MACs. When I searched the web for virus with the number 5 I found they were animal related, human related and Windows related causing Windows not to respond to anything pressed or opened or typed, Similar to the Vista Antivirus 2006, 2009 and 2010 which is a bogus program. If this doesn't answer your question, need more specific details.
A quick list of Linux and Unix virsuses:
Trojans
* Kaiten - Linux.Backdoor.Kaiten trojan horse[15]
* Rexob - Linux.Backdoor.Rexob trojan[16]
Viruses
* 42
* Arches
* Alaeda - Virus.Linux.Alaeda
* Bad Bunny - Perl.Badbunny
* Binom - Linux/Binom
* Bliss
* Brundle
* Bukowski
* Caveat
* Coin 8]
* Diesel - Virus.Linux.Diesel.
* Hasher
* Kagob a - Virus.Linux.Kagob.a
* Kagob b - Virus.Linux.Kagob.b
* Lacrimae (aka Crimea)
* MetaPHOR (also known as Simile)
* Nuxbee - Virus.Linux.Nuxbee.1403
* OSF.8759
* PiLoT
* Podloso - Linux.Podloso (The iPod virus)
* Rike - Virus.Linux.Rike.1627
* RST - Virus.Linux.RST.a (known for infecting Korean release of Mozilla Suite 1.7.6 and Thunderbird 1.0.2 in September 2005
* Satyr - Virus.Linux.Satyr.a
* Staog
* Vit - Virus.Linux.Vit.4096
* Winter - Virus.Linux.Winter.341
* Winux (also known as Lindose and PEElf)
* Wit virus
* ZipWorm - Virus.Linux.ZipWorm
Worms
* Adm - Net-Worm.Linux.Adm
* Adore
* Cheese - Net-Worm.Linux.Cheese
* Devnull
* Kork
* Linux/Lion
* Mighty - Net-Worm.Linux.Mighty
* Millen - Linux.Millen.Worm
* Ramen worm
* Slapper
* SSH Bruteforce