Can I catch vampirism then decide to cure it and then one day catch it again and cure it?Can it be cured an infinite amount of times?
No, if you are a full vampire as far as I know it is a one time only deal. Same if you become a werewolf and get cure of that.
However if you contract the condition and cure it within the 3 day period with standard cures (that us before you become a full vampire) you can contract it again if you wish.