VTEC

What is VTEC?
VTEC are a particular group of the bacterium Escherichia coli. The commonest member of this group of bacteria in Ireland is E. coli O157:H7. E. coli O26 is the next most common strain. Although most strains of E. coli are harmless and live in the intestines of healthy humans and animals, this strain produces a powerful toxin and can cause severe illness.  

Around the world, the number of people infected with VTEC has been increasing since its discovery during the early 1980s. In 1996, Scotland had a large outbreak that affected over 500 people and 17 people died as a direct result of the outbreak. In the last couple of years in Ireland the number of reported E. coli O157 cases is on average 90 per year. VTEC is a notifiable disease in Ireland.

What are the symptoms of VTEC infection?
VTEC infection often causes severe bloody diarrhoea and abdominal cramps although sometimes the infection causes non-bloody diarrhoea or no symptoms. Usually there is little or no fever, and patients recover within 5 to 10 days.

In some persons, particularly children under 5 years of age and the elderly, the infection can also cause a complication called haemolytic uraemic syndrome (HUS), in which the red blood cells are destroyed and the kidneys fail. This happens in up to 10% of cases. HUS is the principal cause of acute kidney failure in children, and the majority of cases of HUS are caused by E. coli O157:H7.

How is VTEC spread?
The organism can be found on a small number of cattle farms. It can live in the intestines of healthy cattle and sheep and can be shed in their faeces.

Meat can become contaminated during slaughter, and organisms can be thoroughly mixed into beef when it is minced. Eating meat (especially minced beef) that has not been cooked sufficiently to kill E. coli O157:H7 can cause infection. Although the number of organisms required to cause disease is not known, it is suspected to be very low.

The organism is found in the faeces of infected persons and it can be passed from one person to another if hygiene or hand-washing habits are inadequate. This is particularly likely among toddlers who are not toilet trained. Family members and playmates of these children are at high risk of becoming infected. Remember, infected persons can shed the organism in their faeces for a few weeks after they recover.

Those who have contact with livestock, either through the course of their work or while visiting farms, should be aware that the organism can be transferred from faeces present on the animal hide to their hands and clothing. Grazing land can also be contaminated with animal waste and recreational users of land (e.g. campers and hill-walkers) can become infected through contact with contaminated grass and soil. A number of outbreaks in the UK have been associated with visiting petting farms (information on how to protect yourself and children in your care on petting farm visits can be found here).

Sometimes, water sources can become contaminated with animal waste (manure). Drinking or swimming in untreated contaminated water can result in infection.

Bacteria present on the cow's udder or on equipment may get into raw milk. Infection can occur following the consumption of unpasteurised milk. Salad vegetables that are consumed raw have been known to cause infection.

How is VTEC infection diagnosed?
Your doctor will ask you to submit one or more faeces samples to see if you are infected.

How is the illness treated?
Most persons recover without antibiotics or other specific treatment in 5-10 days. There is no evidence that antibiotics improve the course of disease, and it is thought that treatment with some antibiotics may precipitate kidney complications. Anti-diarrhoeal agents, such as loperamide (Imodium), should also be avoided.  

Haemolytic uraemic syndrome is a life-threatening condition usually treated in an intensive care unit. Blood transfusions and kidney dialysis are often required. With intensive care, the death rate for those who have HUS is 3%-5%.

How long are you infectious when you have VTEC infection?
You become infectious once you begin to have diarrhoea and you remain infectious for as long as you pass E. coli O157 bacteria out of your body in your bowel motions. Adults tend to be infectious for about a week or so, but children tend to be infectious for longer periods, usually about two weeks. In a small number of cases, young children can continue to be infectious for several weeks (even after their diarrhoea has stopped). Children who are still infectious with E. coli O157 bacteria in their bowel motions will not be allowed back into crèches or other childminding centres until they are free of infection because of the risk of infecting other children or staff.

What are the long-term consequences of infection?
Persons who only have diarrhoea usually recover completely.

About one-third of persons with HUS have abnormal kidney function many years later, and a few require long-term dialysis. Another 8% of persons with haemolytic uraemic syndrome have other lifelong complications, such as high blood pressure, seizures, blindness, paralysis, and the effects of having part of their bowel removed.

What can you do to prevent VTEC infection?

  • Cook all minced beef and hamburgers thoroughly until the juices run clear.
  • Avoid spreading harmful bacteria in your kitchen. Keep raw meat separate from ready-to-eat foods. Wash hands, counters, and utensils with hot soapy water after they touch raw meat.
  • Drink only pasteurised milk and juice.
  • Wash fruits and vegetables thoroughly in drinking water, especially those that will not be cooked.
  • Drink water that has been treated with chlorine or other effective disinfectants.
  • Make sure that persons with diarrhoea, especially children, wash their hands carefully with soap and warm water after bowel movements, and that persons wash hands after changing soiled nappies. Anyone with a diarrhoeal illness should avoid swimming in public pools or lakes, sharing baths with others, and preparing food for others.
  • Wash hands thoroughly after contact with farm animals and animal faeces.

Further information can be found in Verotoxigenic E.coli O157 Annual Reports. 

Last updated: 25th September 2009