Eli5; how we find “patient zero” when there is disease outbreak? (Like how they found who started the ebola outbreak in 2014)

Question

Eli5; how we find “patient zero” when there is disease outbreak? (Like how they found who started the ebola outbreak in 2014)

In: 5171

Answer 1

Doctor to Patient 2: “Who’d you kiss?

Patient 2: “Patient 1”

Doctor to Patient 1: “Who’d you kiss?”

Patient 1: “Patient 0”

There’s you some Eli5