"The organ transplantation occurred more than a year before the recipient developed symptoms and died of rabies, " the CDC said, adding such an incubation period is much longer than usual but not unheard of.

BBC: Rabid organ transplant kills Maryland man

He said one of the main issues was asking a potential recipient if they are happy to receive such an organ.

BBC: Repaired organs for transplant

The Kepners knew a double hand transplant meant Kepner would have to take drugs to suppress his immune system for the rest of his life (like any transplant, the recipient's immune system could attack the new organ as a foreign object).

CNN: Pastry chef receives double hand transplant