So, how is it possible for the virus to get into a high-tech barn? Simple: the birds still need to breathe, which requires a ventilation system of some kind, which allows an entry point for the virus. Phillip Clauer, a professor emeritus of poultry science at Penn State, explains: “In the Midwest, they are working the fields in the fall, and you’ll see dust coming up from the fields, and the geese will land there to glean the extra corn, and they crap in the field. The dust goes aerosol, and that dust travels a long distance. We had one infected layer house in Pennsylvania, and they could tell you exactly what air vent the virus came in from. And then it spread through the whole flock.”

Why not use HEPA filters in the ventilation system?