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

They try to figure out who the first person that got sick was. They ask the first people who got sick and work backwards until there is nobody left.