What is VTEC or E. coli O157?

VTEC is the abbreviation used for Vero cytotoxin producing Escherichia coli of which O157 is the most common in the UK. These bacteria cause gastrointestinal infection resulting in a range of symptoms from mild diarrhoea to haemorrhagic colitis (severe abdominal pain and bloody diarrhoea). Bloody diarrhoea is seen in about 50 per cent of VTEC O157 cases confirmed by laboratories in England and Wales. Some people can carry VTEC without developing symptoms.
A small proportion of patients, mainly children, may develop haemolytic uraemic syndrome (HUS) which is a serious life-threatening condition resulting in kidney failure. HUS develops between 2 and 14 days after onset of diarrhoea (average 6 days) and is a complication affecting 2-7% overall of VTEC O157 cases. 
Very few bacteria (possibly fewer than 100 individual cells) can cause disease. 

The most effective way to avoid infection with VTEC and other gastrointestinal pathogens is to observe basic hygiene precautions which include:

• Wash your hands regularly with soap
• Try to avoid touching your face with your hands, unless they're clean
• Clean hard surfaces with a disinfectant regularly

How do you become infected with VTEC?

Cattle are the most important reservoir of VTEC.  VTEC have been found in the faeces of a range of animals, including deer, rabbits, horses, pigs and wild birds.  People can become infected by:

• Eating contaminated food (see below - How do I avoid being infected?);
• Contact with infected animals either directly by touching or through inadvertent contact with animal faeces (eg at farms, petting farms and campsites);
• Contact with other people who have the illness (i.e. through inadequate hand hygiene after using the toilet and/or before food handling - particularly in households, nurseries and infant schools);
• Drinking water from inadequately treated water supplies;  
• Swimming or playing in contaminated water such as ponds or streams.
  

Is it infectious?

VTEC are very infectious because so few bacteria are needed to cause illness. This means that disease can spread easily within families and in other settings such as day nurseries, primary schools nursing homes and hospitals where there are young children and others who might have difficulty in keeping clean, washing hands, sucking thumbs etc.
Infected food handlers pose a risk of contaminating food products and must be excluded from work to avoid spreading infection. Generally, the bacteria are naturally cleared rapidly from the intestines of humans, but some people can 'shed' VTEC for several weeks after symptoms have stopped.

How do I avoid being infected?

Handle all food and drink safely.  That means: 

• Cooking all minced meat products (i.e. burgers, meatloaf, meat balls etc.) thoroughly, until the colour is the same all the way through, and no blood runs from them;
• Ensure that refrigerators are working correctly, bacteria grow more quickly at temperatures over 4^oC;
• Only leave cooked foods, meat and dairy products out at room temperature for a short time;  
• Store uncooked meats below cooked meats and salad vegetables to avoid dripping juices onto ready to eat food;
• Store uncooked and cooked meats on different plates, avoid all contact between raw and cooked meats;
• Thoroughly wash all salad vegetables that will be eaten raw, do not prepare them with utensils that have also been used for raw meat; 
• Children and the elderly who are particularly susceptible to the severe effects of VTEC should avoid eating or drinking unpasteurised dairy products;
• People who have been ill should not prepare food for others for at least 48 hours after they have recovered;
• Boil any drinking water if you are unsure of it's source;
• Do not swim in water that you think may be contaminated by cattle and sheep in nearby fields;
• Wash your hands  thoroughly after using the toilet (or helping others including changing nappies), handling raw meat, before meals and after contact with animals.

If someone in the family has VTEC infection, wash all dirty clothes, bedding and towels in the washing machine on the hottest wash cycle possible. Clean toilet seats, toilet bowls, flush handles, taps, hand basins and any other areas that might have been soiled with detergent and hot water, rinsing with household disinfectant.

What are the symptoms of infection?

People infected with VTEC can have a combination of the following symptoms:

• Diarrhoea (about 50% of cases have bloody diarrhoea);
• Stomach cramps;
• Fever.

Some people may have mild diarrhoea, or even no symptoms at all (termed asymptomatic carriage). A small number of patients may develop haemolytic uraemic syndrome (HUS) which is associated with anaemia, kidney failure and bleeding. Symptoms of HUS can include weakness, lethargy, sleepiness, paleness, irritability and small unexplained bruises. The symptoms of HUS may resemble other medical conditions or problems so the GP should be consulted for a diagnosis. Such complications are more common in the young (less than 5 years) and elderly (over 65 years). When complications develop, the patient needs to be admitted to hospital.
On average, it takes 3-4 days after consumption of the bacteria for symptoms to develop, but this can be between 1 and 10 days. Symptoms can last up to 2 weeks in cases without complications. Most people rid themselves of the bacteria after about 1 week, though children may carry it for longer periods.

How is the infection treated?

There is no specific treatment for VTEC infection.

The illness is usually self-limiting, and will clear itself within a week. It is important to drink plenty of fluids as diarrhoea can lead to dehydration. A rehydration solution (available from a pharmacy) may be advised by your GP. If you feel sick, take small sips of fluid, frequently.  Avoid tea, coffee, fizzy drinks and alcohol, and dilute sugary drinks. A simple painkiller like paracetamol can help combat any pain.

Antibiotics are not recommended, and are likely to increase the risk of getting complications such as HUS. When complications develop, patients need to be admitted to hospital.

What happens if I am (or my child or parent is) diagnosed?

Your local Health Protection Unit (HPU) will be notified by the local laboratory, and someone from the HPU or the Environmental Health team in your area will contact you to investigate possible causes of the infection. You will be asked several questions about foods you have eaten, places you have been and activities you have undertaken. Your answers may help prevent other people from being infected. You may be excluded from work/school or other institutional settings until 48hrs after you have stopped vomiting or having diarrhoea unless you belong to one of the following groups of people who should be screened for VTEC in their stools:

1. Those that cannot ensure personal hygiene at home, work or school;
2. Those attending pre-school groups  or nurseries;
3. Those that prepare or serve unwrapped food that is not heated further;
4. Healthcare workers with direct contact to highly susceptible patients, or patients for whom an infection like VTEC could have serious consequences.

 

Last modified: 29 July 2009