E. coli 0157:H7 has posed a lots health problems in America. It is estimated to cause infection among more than 70,000 individuals annually in the United States. According to the U. S. Centers for Disease Control and Prevention (CDC) (1) suggests E. coli 0157:H7 is accountable for the vast E. Coli cases reported in the U. S.

Escherichia coli, or E. coli, is a common bacterium that resides in the intestines of almost all warm-blooded animals, including human beings. In fact, we have billions of E. coli bacteria in our guts. Although the bulk of strains are harmless, they are proven to be advantageous to their hosts as they produce vitamin K, which is a key micronutrient. And they also help to crowd out other, more harmful bacteria.

E coli O157:H7 is a serotype of E. coli bacteria. According to a research, a small number of E. coli 0157:H7 are enough to cause turmoil. Ingestion of about 10–100 organisms are enough to cause infections compared to thousands to millions by other E. coli serotypes.

In a study, the CDC team first recognized diarrhoeal illness when isolating E. coli O157:H7 from patients in two different outbreaks in Oregon and Michigan. The ailments were linked with eating hamburgers at a restaurant. Some patients developed inflammation and bleeding of the colon, which is commonly referred to as hamburger disease. Since then E. coli 0157:H7 has been linked with contaminated water, foods, and unpasteurized dairy products.

The most recent epidemic occurred in November 2010 in California, Arizona, Colorado, New Mexico and Nevada. The CDC team associated the outbreak to Gouda cheese that were given away as free samples at Costco stores.

Who is at risk?

Children under the age of five and the elderly are predominantly at risk as they tend to have fragile immune systems. Both these groups also have reduced concentrations of beneficial microbes called bifidobacteria in their intestines that actually stop and fight E. coli O175:H7 infections. Both the young and old are also susceptible to dehydration caused by insistent diarrhoea.

A few E. coli strains, can do a lot of damage. Among the most deadly of these is the O157:H7 strain that causes diarrhoea, frequently with blood in the stools, and stomach cramps. These symptoms usually last up to a week. More severe infections can lead to haemolytic-uraemic syndrome that causes damage of red blood cells and kidney failure. Some strains of E. coli can cause severe diarrhoea and infect the genital and urinary tracts.

How is it transmitted?

E. coli O157:H7 can be passed on from one person to another, generally by direct physical contact It is transmitted as a food-borne ailment, usually in beef. The strain does not harm cattle. In fact, around 15 per cent of cattle are known to be infected with it.

The danger to human beings comes when beef from infected cattle is contaminated with faeces or gut while slaughtering or butchering. Although the bacteria can be destroyed by cooking fully, undercooked beef and mince can pose a great contamination risk.

The bacteria can also be passed on to humans from infected animals, especially when a person touches them. Faeces containing E. coli O157:H7 come into contact with a person’s hands and may travel into the mouth.

In 2010, the FDA recalled several manufacturers of beef, including beef placed in pet food.

Symptoms and Diagnosis

The first signs of E. coli O157:H7 infection normally appears about 3-5 days after a person consumes the bacteria. The main symptoms include nausea, vomiting, stomach cramps and severe diarrhoea that is often mixed with blood. Patients develop a mild fever too.

Patients could also develop later complications that fall into 3 categories:

Hemorrhagic (bloody) diarrhoea: Hemorrhagic diarrhoea symptoms are large amounts of blood in the diarrhoeal stool that does not seem to end. It is accompanied by acute abdominal pain. Although a patient may get better within a week, some of them could get anaemia and dehydration that can cause death.

Hemolytic-uremic syndrome (HUS): Hemolytic-uremic syndrome symptoms are fever, nose bleeding, fatigue, shortness of breath, swelling of the body, particularly hands and feet, jaundice, and less flow of urine. E. coli 0157:H7 generates toxins that damage the kidneys and kills platelets that can lead to kidney failure, excessive bleeding, seizures or death.

Thrombotic thrombocytopenic purpura (TTP): Thrombotic thrombocytopenic purpura is the result of loss of platelets. The symptoms include fever, weakness, bruising, renal failure, and mental harm that can quickly escalate to organ failures and death. With the latest plasma exchange and infusion techniques, there is a drastic reduced death rate in TTP patients.

The diagnosis of E. coli 0157:H7 infection starts with a precise history, physical examination and a scrutiny of a stool sample. A deductive diagnosis is normally made if the patient has symptoms of bloody diarrhoea and a history of being exposed to persons, foods or liquids known to be a source of an E. coli 0157:H7 outbreak.

Due to the high regularity of outbreaks of E. coli 0157:H7, the Centers for Disease Control and Prevention has advised patients should be screened first for diarrhoeal infections by having their stool samples checked with antisera for Shiga toxins, which are produced by E. coli 0157:H7. This method is considered to result in faster diagnosis.

Treatment and Prevention

E. coli O157:H7 infections are treated with anti-diarrhoeal medication and fluid replacement. Paracetamol can be used to manage stomach pain. Antibiotics are proven ineffectual and could do more damage than good by killing useful gut bacteria, which actually helps keep the infection in check.

The U. S. Centers for Disease Control and Prevention recommends the following methods to prevent infections from E. coli 0157:H7:

  • Wash hands properly after using the bathroom and before making or eating food. Wash hands after contact with animals or their environments, especially at a farm, zoo, fair, or even your own pets at home.
  • Cook meats thoroughly. Ground beef and meat must be cooked to a temperature of at least 160 F (70 C).
  • Do not consume raw milk, unpasteurized dairy products, and unpasteurized juices like fresh apple cider.
  • Avoid swallowing water while swimming or playing in pools, lakes, ponds and streams.
  • Prevent cross-contamination in food preparation areas by properly washing hands, cutting boards, and utensils after you touch raw meat.
  • Hamburgers ordered in a restaurant should be cooked thoroughly so that no pink hamburger meat is seen inside. This way of cooking cuts down the chance of E. coli being alive in the meat.
  • As E. coli 0157:H7 is usually found in the intestines of cattle, companies have introduced a vaccine to cut down the number of these bacteria in cattle. The first vaccine for cattle was approved by FDA in 2009. There is no E. coli 0157:H7 vaccine currently available for humans.

As they say, prevention is better than cure. A general awareness about what you eat will help you stay away from catching infections.. Remember to avoid touching or consuming any food that you think may be contaminated with any animal or human waste.

1) U. S. Centers for Disease Control and Prevention (CDC)



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