Food and water borne illnesses have been killing humans since the beginning of humanity. Sometimes it feels as if humans are under assault by their food supply. Most microbes do us no harm, and are often critical to our survival. Some strains, however, are dangerous for humans and other forms of life, and others only become dangerous in high concentrations.
Ever since people invented cities, these concentrations of people have been home to epidemics caused by concentrations of microbes eating human food and wastes. It was not until the invention of modern sewer systems and protected water supplies that cities could grow in population.
The birth of cities coincided with the birth of mass scale agriculture. From the fields of Mesopotamia to the miracle of California’s Central Valley is not that big a step. In 1977 I irrigated fields in Idaho with a technology every Mesopotamian farmer would understand. And just as Mesopotamian cities and farming towns mismanaged their human and animal fecal wastes, resulting in large disease burdens, the agriculture practiced in 21st century America is still plagued by bacteria, in addition to diseases caused by modern chemicals.
Last year, we saw outbreaks of two kinds of bacterial diseases caused by various strains of Salmonella found in various meat products and diseases caused by Escherichia coli, also known as E. coli, a bacterial species that is common in the intestinal tracts of nearly every mammal. Both cause serious and occasionally fatal bouts of diarrhea and other gastro intestinal symptoms.
Salmonella seems to be a problem because in high density industrial animal feedlot farming, poop is everywhere, which means Salmonella is everywhere. Cleanliness really counts, but expect that there will be some Salmonella in all industrial meats. Therefore, cleanliness really counts at home, too. Outbreaks in 2018 were from turkey with high Salmonella counts being handled. Not from the post cooking eating. But with the huge demand for food from the growing global middle class we may not be able to raise enough food in the near term without industrial facilities. If you have enough money, you can find healthier meats closer to home, but mass demand will be met in ways that make Salmonella outbreaks nearly inevitable, maybe even after we truly clean up and green agriculture.
Last year’s Romaine lettuce story is even more devious. The particular strain of bacteria, E. coli O157:H7, is not only particularly nasty, but appears to be specifically adapted to living on Romaine lettuce and further attracted to the extra sugars produced as lettuce is cut up for prepackaged salads. In both the California and Arizona outbreaks the E. coli appears to have reached the lettuce fields via contaminated irrigation water. Irrigation water is simply untreated river water that is channeled into canals and flows for miles and miles until it reaches the field where it will be used to irrigate. Do cattle graze near any of the tributaries? Did dog poop get washed in during the spring melt in the mountains? Did a cat drown? How do you keep everything away from miles and miles of open canals, including some running through farms and some running through cities?
This same contaminated irrigation water is used on a variety of crops, most of which do not cause disease outbreaks. Much of the difference is cooking. Cooking kills E.coli, but we do not cook lettuce and unfortunately, washing seems to have no affect on this pathogen. It even thrives in the wet conditions among the leaves. Yikes.
People are going to continue to eat irrigated lettuce. The government is going to continue to provide laxer standards of cleanliness in the agribusiness world due to the pressure of corporate campaign contributions and lobbying. Bacteria are going to continue to evolve, with new strains taking advantage of all the imbalances we create feeding eight billion of us. And maybe it is not fair to single out Romaine lettuce, though E. coli O157:H7 has, but if we are not going to avoid it entirely, cast a wide net checking for disease outbreaks associated with it, as the rate of them seems likely to increase.