Seems like this is a simple sort of connect-the-dots story. California farmers plow spinach fields under - U.S. Business - MSNBC.com
Most of the agro-workers in California are illegal immigrants. Illegal immigrants working in the fields do not get any sort of health care.
E.Coli is a bacteria common in every human stomach. There are lots of different strains of E.Coli - so what lives in one person’s stomach without harm might make another guy very sick.
So we get a very sick Mexican (most likely) taking a dump (a symptom of this strain) in a spinach field. The harvested spinach all goes into one batch washed together - contaminating the entire batch. The bagged spinach is eaten by a large number of folk - some who die from the unfamiliar E.Coli strain.
Maybe we do care about the health of farm workers.