Escherichia coli O157:H7 is an Enterohemorrhagic strain of the bacterium Escherichia coli and a cause of food borne illness whose infections leads to hemorrhagic diarrhea, and occasionally to kidney failure, especially in children and the elders. This illness is mostly associated with eating undercooked, contaminated beef. Simply put, E.coli 0157:H7 is a mutant form of a bacteria found in particular in the intestinal tract of cattle. E.coli 0157:H7 is distinguished by severe crampy abdominal pain, watery diarrhea then followed by grossly bloody diarrhea, and fever. (Riley, 1983)
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What could account for the increase in cases of Escheria coli O157
In September 1985, an outbreak of Escherichia coli O157:H7 enteritis affected seventy three residents and staff members of a nursing home. This outbreak was characterized by two phases. One was the primary wave whose source was found to be a contaminated sandwich meal while the secondary wave was the person to person transmission of infection. The incubation period among the elderly was between four to nine days which meant that older age and previous gastrectomy increased the risk of acquiring the infection. An antibiotic therapy during exposure was also associated with acquiring a secondary infection. A total of nineteen residents died.
Eleven of them had developed Hemolytic uremic syndrome from causes that is attributed to their infection. Antibiotic therapy after the onset of symptoms was associated with a higher case fatality rate in the more severe cases, possibly because patients with more severe disease tended to be treated with antibiotics. There were no complications or deaths among the affected members of the staff. Proof of infection by verotoxin-producing E. coli O157:H7 was detected in several cases on the basis of isolation of this organism or demonstration of free verotoxin in stools. All isolates belonged to the same phage type. The high morbidity and mortality associated with this condition stresses the need for appropriate food hygiene, rapid identification of outbreaks of disease, and prompt institution of infection-control techniques among the institutionalized elderly. (NEJM, 1987)
Ground beef is the most common source of E. coli O157:H7 transmission especially if it is taken when raw or undercooked. Another source is raw milk. These bacteria are found in animal feces, particularly cattle feces, and contact with the feces can also lead to contamination of many types of food and fluids. E. coli O157:H7 can less commonly be transmitted from one person to another, usually by direct physical contact although the infectious dose is low, even limited deficiencies in food preparation or handling can result in exposure and infection. To prevent infections, hygienic measures have to be undertaken which include washing of hands thoroughly after use of toilet or before preparation of food, cooking of meat thoroughly and avoiding swallowing of water in a swimming pool or drinking of untreated water. Measures for preventing cross-contamination include washing hands and surfaces after contact with raw ground beef, storing raw ground beef to ensure that drippings do not contaminate other foods, and using different utensils to handle raw and cooked meat.
In addition, many researchers suggest that food such as hamburgers ordered in a restaurant should be cooked through completely, so that no pink hamburger meat is visible inside. This cooking reduces the chance that E. coli will remain alive in the meat. All foods involved in a recall should be put in the trash. No one should attempt to cook the recalled material and eat it. Because E. coli 0157:H7 is routinely found in the intestines of cattle, companies have developed a vaccine to reduce the number of these bacteria in cattle. The first vaccine for cattle was FDA approved in 2009. There is no vaccine available for E. coli 0157:H7 in humans. (webMD LLC, 1994)