system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does patient zero get sick?

When a new outbreak starts, how does the first person get sick? Is it from asymptomatic carriers, travelling and picking up foreign strains of illness, mutations, or what?
gpt
Few options.

Then can be the person in which there was a mutation that allowed the disease to evade the community's immunity. Or they can be the person who brought the disease from a foreign country, or caught it from an animal.