With that much extra feed, nobody makes money. Either that, or supermarket prices go way up. But the biggest problem is that no other country will buy our products. The export market dries up, and exports drive the domestic market. But humans don't get it.
People can carry it in the back of their throat.
It doesn't get into the cells and so doesn't infect you, but you can go a day later to a circus or a feed lot and sneeze and start an outbreak. But it's passive. If the naked viral particles are exposed to heat or sunlight or drying, they die in a matter of hours. But if they're within something cool and moist, with some organic material, they can survive for quite a while. The virus can survive in a little piece of manure on the bottom of your shoe for probably a month.