text:  We have a pretty good idea. They were working at a big commercial poultry farm that had an outbreak of H5N1 bird flu, and these workers were responsible for culling and disposing of these birds, which means they were handling them, they were putting them in carts that are used to euthanize the animals. That's already a high-risk activity, but it turns out these barns were also baking in the summer heat. There were big industrial fans going. All of this made it hard for them to properly wear protective equipment over their eyes, their mouth, and their nose.