What is VTEC?
VTEC are a specific 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, the VTEC strain produces a powerful toxin which can cause severe illness, particularly in children under five and the elderly. The infection can be passed from person to person, through consuming contaminated food or water or contact with infected animals or contamination in the environment.
VTEC is a notifiable disease in Ireland.
What are the symptoms of VTEC infection?
VTEC infection causes abdominal cramps and diarrhoea but can sometimes cause bloody diarrhoea. In some cases, VTEC infection can be asymptomatic, meaning that the infected person has no symptoms and does not know that they have been infected. Usually there is little or no fever, and patients recover within 5 to 10 days. It is important to visit your doctor if you develop bloody diarrhoea.
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 can stop working properly. 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?
VTEC can be found on a small number of cattle farms. It is found in the intestines of up to 5% of healthy cattle. VTEC bugs can then be shed in the manure of infected animals. It can also be found in healthy sheep.
Meat can become contaminated during slaughter, and the bugs can be 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. One feature of VTEC that makes it particularly dangerous is the very low number of bugs needed to make a person sick; as little as a single VTEC bug can be enough to make you ill. This is hundreds of times less than the number of bugs needed to make you sick with salmonellosis and campylobacteriosis.
The bug can be found in the bowel motions of infected persons and it can be passed from one person to another if hygiene or handwashing 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. Infected persons can shed the organism in their bowel motions for a few weeks after they recover. Therefore, even if you do not have symptoms, you can infect others if your hygiene is not adequate.
Those who have contact with livestock, either through the course of their work or while visiting farms, should be aware that the bug 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. And land that has recently had slurry spread upon it can potentially pose a risk. 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.
VTEC can also be found in food and liquids. If the bug is present on the cow's udder or on equipment, it may get into the raw milk, and infection can occur following the consumption of unpasteurised milk. Salad vegetables that are consumed raw, having been irrigated with contaminated water, or contained in some other way by animal manure, can also 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?
It is important to drink plenty of clear fluids to prevent dehydration – take small, frequent sips of water.
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 increase the risk of kidney complications. Anti-diarrhoeal agents, such as loperamide (Imodium), should also be avoided.
HUS 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 - you can still pass the bacteria in your faeces even after your symptoms have settled.
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).
Young children who are still infectious with E. coli O157 bacteria in their bowel motions may 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. Your local department of public health will be able to advise you on this.
If you have been diagnosed with a VTEC infection by your doctor and you work in a childcare facility, as a healthcare worker or you handle unwrapped foods as part of your job, you may not be allowed to return to work until you are free of infection. This is to reduce the risk of passing the infection to other people. Your local department of public health will be able to advise you on this.
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?
- When preparing food:
- Wash your hands before and after handling food.
- Unless a food product is meant to be cooked straight from frozen, make sure that any frozen foods have been thawed out before you start cooking them.
- Use separate cooking utensils and plates for handling raw and cooked meats.
- Make sure that any minced meats such as burgers are cooked all the way through. You will know when a burger is fully cooked when the meat is piping hot throughout, there is no pink meat when you cut into the middle of the burger and the meat juices run clear.
- Wash fruits and vegetables thoroughly in drinking water, especially those that will not be cooked.
- Drink only pasteurised milk and juice.
- Drink water from a safe source e.g. treated tap water.
- 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, paddling pools and preparing food for others.
- Wash hands thoroughly after contact with farm animals and animal faeces.
- Do not allow children to attend crèche or school if they have vomiting and/or diarrhoea and should continue to stay away for 48 hours after their first normal bowel motion.
- Staff in childcare facilities, healthcare workers and food handlers should not attend work when they have vomiting and/or diarrhoea and should continue to stay away for 48 hours after their first normal bowel motion.
Further information on the epidemiology of verotoxigenic E. coli O157 in Ireland can be found in Verotoxigenic E.coli O157 Annual Reports.
Last updated: 19 July 2018