A fourth patient, who also received a kidney transplant, became ill but is now recovering.
Research discovered the donor had a rare rodent-borne disease, lymphocytic choriomeningitis virus, which she possibly contracted from her pet hamster.
Public health officials say this is only the second documented case of LCMV spreading through an organ transplant and urged those on the transplant waiting list not to worry.
The connection was made when a doctor at one of the transplant hospitals reported an unusual viral death, which investigators traced back to the donor.
The donor died of circumstances unrelated to LCMV.
The patients have not been identified.
