What a massive over reaction.
I'd much sooner get a little nibble on my shoulder than have some guy bobsled me and get my leg busted.
When that happens I don't see such an outcry and people demanding a long ban.
Its all a beat up by the English press who hate Suarez.
Plus "a little nibble" is not really accurate, he sank his teeth in pretty hard by the looks of it, and judging by the photos I've seen of Chiellini's shoulder, he broke the skin too. That can lead to some pretty nasty complications:
http://emedicine.medscape.com/article/218901-overview
Human bites have been shown to transmit hepatitis B, hepatitis C, herpes simplex virus (HSV), syphilis, tuberculosis, actinomycosis, and tetanus.
Evidence suggests that it is biologically possible to transmit the human immunodeficiency virus (HIV) through human bites, although this is quite unlikely.