With regards to the conditions of food in the 1850's, something of import did occur to me. (after 25 years as an RN. . .Hey, I ARE BRIGHT!)

Seriously though. In most of our lifespans we have seen people become totally germaphobe fearing simpletons. Case in point, if you grew up in the 40's to the early 70's. kids eating dirt was normal. Gross perhaps, but it served a vital function to prime their immune systems. Today however, everything gets multiple wipes of antibacterial wipes and heaven forbid baby eats a bug! The results of such anti priming behavior was to set the person up with little immune system as an adult. They get sick at the sound of a cough.

See:
https://www.sciencedirect.com/science/article/pii/S0092867412001043
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4707740/
https://www.nytimes.com/2009/01/27/health/27brod.html
http://healthland.time.com/2010/12/03/can-overuse-of-antibiotic-soap-promote-allergies-in-kids/

Which, by extension, a more robust immune system is going to be more tolerant of bacteria in food.

People need to quit freaking out at any idea of bacteria. Send the kids out to eat some dirt!
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WesleyH