0 the first person in a group known to be suffering from a disease or medical condition that can be passed on to others, either through infection or in the genes:
The possibility of transmission from the index patient on these two flights cannot be excluded.
Index patients and all available family members were invited for clinical examination.
He was the index patient in a deadly outbreak at the hospital in the early 1990s.
Nose, throat and wound cultures were taken from staff and patients who had had contact with the index patient.
The index patient had a twin brother who suffered from spina bifida and three other siblings with heart conditions.
Four of seven children of the index patient's aunt (father's side) died suddenly at an early age.
