So larryc, you suggest I talk to HR, rather than the search committee?
It depends. At our place, HR is not involved at all in hiring until the offer is made. So at our place, the contact should be made with the Search Committee Chair.
See if there is any flexibility. Perhaps you could do a skype interview?
You really need to judge by who you have been talking to up to now. If it is the SC Chair, then a conversation (not an email!) with them would be useful now .
Without revealing anything about your medical condition, can you say to the SC whether there will be any medium or long term effects on your ability to do the job? This would be an important consideration in any hire.