As of 2022, tens of billions of chickens are killed every year to feed humanity’s growing appetite for bird meat. With the rise of avian flu, the number of chickens dying of illness — and being killed en masse preventatively — is even higher.

Highly pathogenic avian influenza can be transmitted among farms by wind, according to a recent study that found air-intake systems spread H5N1 in the Czech Republic.

There is another confirmed case of avian flu in Pennsylvania, this time at a live bird market in Philadelphia County.