I was born with 10 fingers, but when I was 9 months old my finger was amputated and I have no answers, so on my rights hand my 4th finger from my thumb is amputated and so is part of my pinky.. would you know of any diseases in 1964 that would cause a baby to loose her fingers.
Any type of infection that causes tissue death can require amputation. Perhaps something as simple as an infected cut on the finger to something as serious as a bacterial menegitis infection.