Throughout entire human and chicken collective history we somehow haven’t managed to get wiped out by chicken transmitted decease - and suddenly its practically imminent and only massive mega farms can keeps us safe.

A thought occurs - perhaps it’s the mega farming that is the root of this problem and having some backyard chickens won’t really move the needle any closer to doom?

What has changed is the population density of humans. Disease outbreaks aren't at thing you can understand by summing all the disease vectors.

There is no needle - it only takes one case. While a megafarm may be a bigger vector, it can be quarantined, whereas everyone having backyard farms can not.

Major diseases have been a part of human history throughout. There is no evidence that mega farming is making it worse.