I am only guessing, but the Ebola disease found in the romaine lettuce, might be explainable.
When I was a teenager living in Moorhead, Minnesota in the 1950s, I worked in the sugar beet fields with these undocumented people from Mexico.
These fields were 200 acres in size and we had porta potties at each end of the fields to use. These Mexicans workers didn’t always want to walk to the end of the fields so they urinated and defected right in the fields of the produce.
That might explain the Ebola disease. Times have changed over the years but old habits never do.