Interesting side note about the spinach E-Coli outbreak
Where does this particularly virulent strain come from? It’s not found in the intestinal tracts of cattle raised on their natural diet of grass, hay and other fibrous forage. No, O157 thrives in a new — that is, recent in the history of animal diets — biological niche: the unnaturally acidic stomachs of beef and dairy cattle fed on grain, the typical ration on most industrial farms. It’s the infected manure from these grain-fed cattle that contaminates the groundwater and spreads the bacteria to produce, like spinach, growing on neighboring farms.
When cows were switched from a grain diet to hay for only five days, O157 declined 1,000-fold. This is good news. In a week, we could choke O157 from its favorite home — even if beef cattle were switched to a forage diet just seven days before slaughter, it would greatly reduce cross-contamination by manure of, say, hamburger in meat-packing plants.
Seems easy enough to implement, if impossible to enforce.
A more nuanced look, if not a debunking of the above theory can be found on this scienceblogs page.