Spinach Woes

The backpacker's adage, "Peel it, wash it, cook it, boil it, or forget it," for avoiding infectious diarrhea may not be sufficient if the bacteria you are trying to avoid is the Shiga toxin-producing Escherichia coli (STEC). This group used to be classified as enterohemorrhagic (bleeding within the gastrointestinal tract) E. coli. These bacteria have caused outbreaks of diarrhea associated with consumption of contaminated beef (often, fast-food hamburgers), unpasteurized apple juice, raw milk, red leaf lettuce, alfalfa sprouts, and venison meat jerky. Contact with contaminated swimming pools and exposure to farm animals have also been associated with this infection. Now for at least the time being, we have contaminated raw spinach from the Salinas, California farm region, to add to the list, not only in camp but at home as well.

These bacteria proliferate within the bowel of humans, release the Shiga toxin that wreaks havoc upon the bowel, and thereby cause copious bloody diarrhea with mucus (hemorrhagic [bloody] colitis), but fever is either low grade or not present. Typical symptoms include severe abdominal cramping, sudden onset of watery diarrhea, frequently bloody, and occasionally vomiting. Most often the illness is mild and self-limited generally lasting 1-3 days. The most important strain from the human clinical perspective of STEC thus far identified is O157:H7. The production of Shiga or similar toxins by these strains may be linked to the hemolytic-uremic syndrome (HUS), which is a disorder marked by breakdown of red blood cells in the body combined with kidney failure. This is a more common complication in children (as compared to adults) infected with STEC O157:H7. HUS may be life-threatening, and to make matters more complicated for doctors, treatment with antibiotic therapy of STEC colitis does not shorten the duration of diarrhea and is perhaps related to more frequent development of HUS, rather than preventing this complication, by a mechanism(s) that has yet to be fully understood.

So, simply washing a leafy vegetable intended to be eaten raw, like lettuce or spinach, is not sufficient to prevent infection and diarrhea. Apparently, the external surfaces trap and hide bacteria in a manner that prevents their wash-off, even with water that has been disinfected. Referring back to the adage in the first paragraph, you cannot trust washing. Until further notice, if you are going to eat spinach, cook it until it has been boiled, even if it has been thoroughly washed.

Tags: spinach, infectious diarrhea, E. coli 0157:H7, Shiga toxin , wilderness medicine, healthline