In 2006, consumers in the United States experienced a major health scare when bags of raw spinach leaves processed in California were found to contain dangerous levels of a bacteria called Escherichia coli, often abbreviated as E. coli. Hundreds of people were sickened, and several deaths were reported. The source of the E. coli contamination was eventually traced to specific produce farms located in one county in California. While sales of bagged spinach eventually resumed, the public also became aware of some of the dangers of E. coli contamination and exposure.

It is important to realize that not all E. coli bacteria are harmful to humans. The term E. coli applies to a number of bacteria strains present in animal and human digestive systems. Most E. coli bacteria serve a purpose as digestive aids; they are part of the helpful gut flora responsible for breaking down certain foods into more digestible sugars or proteins. One particular strain of E. coli, called E. coli O157:H7, is the form of bacteria responsible for the most serious complications associated with contaminated foods and other sources.

Why is E. coli, especially E. coli O157:H7, so dangerous? For one thing, the first symptoms of true E. coli contamination mimic a number of other conditions considered to be temporary or treatable with standard antibiotics. The sufferer may experience abdominal cramping, diarrhea and nausea. The loss of fluids may also cause dehydration and a general loss of energy. Many people have experienced these symptoms as the result of a 24-hour flu bug, mild food poisoning or general overeating. Parents and other caregivers may not recognize the more serious symptoms of E. coli infection for several days.

Another reason E. coli is so dangerous is that it most severely impacts the young, elderly and immunity-compromised. Healthy adults can usually survive the worst of an E. coli infection, because other elements of their digestive tracts still function normally, and the body's natural defenses can eventually overwhelm the invading E. coli bacteria. Young children have not yet developed these natural defenses, and the elderly or immunity-compromised may not have the healthy levels of gut flora and antibodies required to fend off the infection.

E. coli O157:H7 is particularly damaging to the kidneys and other organs responsible for removing toxins from the body. In young children, E. coli bacteria can create a poisonous toxin that weakens the walls of the small intestine. In turn, the linings of some smaller blood vessels in the kidney can also become weakened. This is a serious complication called hemolytic uremic syndrome (HUS). It is possible for HUS sufferers to experience complete kidney failure or other complications, such as paralysis, blindness and seizures.

E. coli 0157:H7 does not respond well to the traditional over-the-counter remedies for its symptoms. Antidiarrheal medications can make the infection worse, since they prevent the body from naturally eliminating some toxins. Antibiotics essentially kill off any bacteria they encounter, including the good intestinal bacteria strains assigned to fight off the E. coli invasion. Since there is no current treatment for severe E. coli infections, the sufferer must endure the unpleasant symptoms until the infection has run its course, generally within one to two weeks.