The biggest disease is "snake addiction." One leads to many in alot of cases. That then injures your bank account.
The main thing you are going to read about is RI or respiratory infection. They can be causes by many different factors but is mainly avoided by providing the correct husbandry.
Mites is another issue. They can hitchhike home from reptile shows and stores or can come free with a new snake. More of a pain to deal with overall. Search PAM(prevent a mite) or Reptile Spray. They are good for ridding you of them.
That's the main issues I see most here.