Currently, there are four recognized classes of enterovirulent E. coli (collectively referred to as the EEC group) that cause gastroenteritis in humans. Among these is the enterohemorrhagic (EHEC) strain designated E. coli O157:H7. The bacteria Escherichia coli was first isolated by German bacteriologist Theodor Escherich. The bacterium colonizes in the human bowel. While cattle are the main reservoirs of E. coli, sheep, deer, dogs, birds, chickens, and pigs also carry the bacteria. The bacteria can survive in fecal matter for long periods. Researchers find E. coli bacteria, one of the most studied of bacteria, to be useful in genetic engineering and production of insulin.
The first outbreak of E. coli O157:H7 in the United States was in 1982 when 47 victims were stricken by the bacteria in Oregon and Michigan experienced severe cramps and diarrhea after consumption of contaminated beef patties. The 0157:H7 bacteria attacks epithelial cells of the intestine, destroyed blood vessels, and induce hemorrhaging. To determine whether 0157:H7 was a new infectious agent, the Center for Disease Control (CDC) examined E. coli cases from 1973 to 1983. Only one case 0157:H7 was discovered, which suggested that the bacteria was a new strain of E. coli. In 2001, it was reported that the 0157:H7 genome contains 5416 genes, of which 1,387 genes are not in less harmful strains of E. coli.
The largest outbreak in the United States occurred in 1993 when over 90 Jack in the Box restaurants over four states served undercooked hamburgers with E. coli 0157:H7. As a result, more than 700 became ill with over 50 cases of HUS (hemolytic uremic syndrome), a complication of E. coli infection that leads to the destruction of red blood cells and kidney failure. Two of the victims died. 10-year old Brianne Kiner, the most severe non-fatal case, spent 40 days in a coma and 189 days in the hospital where she survived three strokes, thousands of seizures and the massive organ failures.
In 1994, several cases occurred in summer camps where meat was improperly cooked in campfires. E. coli 0157:H7 bacterial agent thrives in undercooked hamburger, cheese curds, salami, unpasteurized milk, and unpasteurized apple cider. In 1995, the DCD started PulseNet, a series of connected public health labs across the country that used pulsed-field gel electrophoresis 'fingerprinting' to monitor foodborne E. coli bacteria.
Between December 1989 and January 1990 in the small southern Missouri town of Cabool, contaminated water resulted in 243 cases of E. coli 0157:H7 with 4 deaths. Canada's largest outbreak was in 1998 in Walkerton where half the town's population- 2,000 people- became infected with E. coli 0157:H7 bacteria, 90 were hospitalized, and 11 died. In 1998, an outbreak happened in an Atlanta, Georgia water park. Low chlorine levels and possible fecal contamination caused the outbreak. 27 children became sick, 6 hospitalized, and one 2-year old girl named McCall Akin died. In 1999, at New York's Washington County Fair, unchlorinated well water was served in drinks and ice, which resulted in over 900 cases of diarrhea, 65 hospitalizations and 2 deaths.
While the malleability of E. coli's genetic material renders it a valuable bacterium for genetic researchers, this malleability also makes E. coli a potentially deadly biological weapons agent. In the late 1980s, US scientists inserted into harmless E. coli bacteria the gene that produced lethal protein in anthrax. In E. coli, the gene was active and produced the same deadly proteins as anthrax. The Iraqi biological weapons program demonstrated interest in the possibilities of altered E. coli bacteria as a biological agent, and it was reported shipments of E. coli was shipped to Iraq from the United States.
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