[ars]

I'm not conflating it. Spread with Avian flu means to other places. A single chicken in a farm means ALL chickens will get it. That's such a trivial thing, it's not even worth noting.

What matters is how does it spread.

I think what's confusing you is that there are diseases where a single infected animal does NOT mean all animals will get it, and in those cases the more concentrated the farm the higher percent of other animals will get it.

That exists. But it's not the case here. Here it's 100%, doesn't matter if it's a concentrated farm, or a pastoral farm with chickens walking in the house.