I have a friend who has one of the strains of Hepatitis - her liver was seriously affected ... She was on a pill that cost $1000 EACH ... but she no longer has the Hep ...

As for the piano job, stay off the piano for a couple of days, then perhaps do some finger exercises and maybe practice a little bit on Tuesday ... I would think that with your ability and experience you will get through the gig with no problems - other than perhaps some pain/discomfort ... BUT REMEMBER - I am not a doctor, nor do I play one on TV ...