I personally think the spread of staph/ringworm has more to do with the school being dirty than the practitioner and/or his/her gear being dirty (more specifically the belt, nasty gi's are nasty gi's, no matter how you spin it).
I've been doing BJJ for over 2.5 years, never washed my belt - been blue belt for a year and a half - nor does anybody I know of in my school wash their belt.
I have NEVER heard of a single staph/ringworm infection, EVER - it even goes beyond my 2.5 years. My instructor often brags about the fact that he's been in business for over 10 years without a SINGLE case of staph/ringworm and nobody disputes this fact (including the people who've been there much longer than me). I forget the name of the stuff he uses to clean the mats, but it kills everything, he washes the mats on a very regular basis. He also attributes this steak to the fact that we use gi pant's and long sleeved rashguards in nogi class.
In conclusion, I highly doubt a dirty belt is the cause of this staph/ringworm "epidemic". Either you're dirty, your gi is dirty, your training partners are dirty, or your school just doesn't take enough care cleaning up after class. But seriously, don't blame the belt.