About 90% of the United States' supply of lettuce in the winter comes from Yuma, Arizona [0].
I think it more appropriate for most people to eat seasonally-appropriate vegetables during the winter months, than to get a little lettuce from thousands of miles away. Winter squash, carrots, apples, and many other food products store very well in root cellars [1].
How does this happen at wide spread scale? I understand that situations occur where birds could track in disease by landing in growing areas but it seems like a more substantial contamination to cause this many infections.
I think it more appropriate for most people to eat seasonally-appropriate vegetables during the winter months, than to get a little lettuce from thousands of miles away. Winter squash, carrots, apples, and many other food products store very well in root cellars [1].
[0] http://www.visityuma.com/agritourism.html [1] https://en.wikipedia.org/wiki/Root_cellar