Yikes! That's quite an economic hit.
Yes, 159,000 culled birds is a lot, and it is a severe economic hit.
Whether or not bird flu ever gets to human-to-human, it's going to take a huge toll.
If you don't cull the birds, they'll all likely die anyway, plus all the more chance for humans to get it. If it's in the migratory birds, and that's how these turkeys caught it, it's going to go all around the world and no place on earth will escape at least the economic hit.
At least with culling there is a slim chance it won't spread to another farm...