Escherichia coli O157, sometimes called VTEC or STEC, is a bacterial infection that can cause severe stomach pain, bloody diarrhoea and kidney failure.
Escherichia coli O157 is not usually carried by humans, but is found in the gut and the faeces of healthy cattle, sheep, deer and other animals. However, in people it produces potent toxins and can cause severe disease.
The number of laboratory confirmations of E. coli O157 in Wales can be viewed from our interactive data dashboard.
E. coli bacteria are very common and there are lots of different strains which are normally found in the gut of many animals, including people and are mostly harmless.
But some strains of E. coli can cause a range of infections which may affect the intestines or other parts such as the kidneys, urinary tract and bloodstream.
Anyone can become infected with E. coli O157 (VTEC O157).
E. coli O157 is very infectious and probably less than 100 organisms can cause illness. The incubation period (between exposure and the occurrence of symptoms) is usually between one and eight days (commomly 3-4 days), although periods as long as fourteen days have been suggested in certain outbreaks.
People become infected through eating contaminated foods, particularly inadequately cooked minced beef (often in the form of beefburgers) and milk (unpasteurised or contaminated after pasteurisation). However, outbreaks have been associated, amongst other things, with yogurt, cooked meats, meat pies, cheese, dry cured salami, raw vegetables, salad vegetables, unpasteurised apple juice and water.
People can also become infected with E. coli O157 from direct contact with animals, their faeces or contaminated environments. Farms can be a particular source of E. coli O157 and information on how to reduce the risk of becoming infected especially when visiting farms on special open day events is available from Public Health England.
Individuals, especially children, who are ill can pass the infection onto others particularly in the same household. A factsheet containing advice for people at home and in other environments where someone has E. coli O157 infection has been produced by Public Health England.
The illness can range from mild diarrhoea to bloody diarrhoea (haemorrhagic colitis) and may be accompanied by severe stomach cramps. A severe complication of E. coli O157 infection is haemolytic-uraemic syndrome (HUS) which occurs in up to 10% of patients infected with VTEC O157. It particularly affects young children and the elderly and in a small number of cases, it can be fatal.
More information about E. coli O157 (VTEC O157) is available from the NHS Direct Wales website.
Most patients with infections caused by E. coli O157 (VTEC O157) do not require specific treatment and make a full recovery, although the advice of a health professional should be sought in all cases of severe diarrhoea. Oral rehydration therapy maybe advised to prevent dehydration. Antibiotics are generally not given in the treatment of this infection as they can increase the risk of complications developing.
It is estimated that about 30% of patients with E. coli O157 (VTEC O157) will require hospital admission. Patients who develop HUS will require intensive support in hospital.
The number of laboratory confirmations of E. coli O157 in Wales can be viewed from our interactive data dashboard.
Large community outbreaks of E. coli O157 (VTEC O157) have been recorded in many countries including Wales. An outbreak of E. coli O157 occurred in September/October 2005 with cases recorded in 44 different schools in the South Wales valleys. In total 157 people, mainly children, fell ill and a five-year old child died.
Adequate control measures and good hygiene practices are important in the prevention of infections due to E. coli O157, these include:
Washing hands thoroughly before eating or preparing food, after using the toilet, changing nappies or cleaning up after others with diarrhoea.
Ensuring meat, especially minced beef, is cooked thoroughly (meat can become contaminated during slaughter, and organisms can be accidentally mixed into meat when it is minced).
Hygienic handling, preparation and storage of raw meat and other animal products and making sure that raw meats and the implements used to handle them do not come into contact with cooked meat or ready-to-eat food.
Washing hands thoroughly after contact with domestic or farm animals or soil; this includes during visits to petting farms/zoos as E.coli O157 can contaminate the ground, railings, feed bins, and fur of the animals. Advice for farmers (including a supplement for teachers) on avoiding ill health at open farms has been published by Farming and Countryside Education and is available on their Visit My Farm website.
Peeling raw fruit and vegetables and washing thoroughly before eating and avoiding unpasteurised milk (which can become contaminated from contact with cows udders) and unpasteurised fruit juices.
Avoiding swallowing water when swimming in untreated or public water facilities.
A factsheet containing advice for people at home and in other environments where someone has E. coli O157 infection has been produced by Public Health England.
Enhanced surveillance of E. coli O157 (VTEC O157) has been undertaken in Wales by Public Health Wales since February 1990. It is one of the most complete surveillance programmes of its type in the world.
This surveillance for E. coli VTEC O157 in Wales provides timely reporting of sporadic cases and enhances detection and containment of outbreaks. It also provides valuable information about E.coli VTEC O157 infections and demonstrates the wide range of associated clinical illness.
CDSC Wales has a downloadable questionnaire for completion by investigators. A copy of the questionnaire should be sent to Communicable Disease Surveillance Centre (CDSC) immediately on completion of the investigation.