What is Verocytotoxigenic Escherichia coli (VTEC)?
VTEC is a particular group of the bacterium Escherichia coli. Although most strains of E. coli are harmless and live in the intestines of healthy humans and animals, VTEC strains produce a powerful toxin and can cause severe illness. In Ireland, the most common member of this group of bacteria is E. coli O157:H7, followed by E. coli O26. Other serogroups commonly linked to human illness in Europe include, O103, O145, O111 and O91.
What is E. coli O104:H4?
This is the VTEC strain that caused an outbreak in Northern Germany in May 2011. It is a very unusual serogroup.
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 at all. Usually there is little or no fever, and patients recover within 5 to 10 days of becoming ill.
In some people, 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 5 to 8% of cases (although rates as high as 30% have been reported during outbreaks).
How soon do symptoms appear?
Symptoms typically appear 2 to 4 days after being exposed to VTEC, although this can range from 1 to 8 days.
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 the 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).
What are the long-term consequences of infection?
People who only have diarrhoea usually recover completely. About one-third of people with HUS have abnormal kidney function many years later, and a few require long-term dialysis. Another 8% of people with HUS have other lifelong complications, such as high blood pressure, seizures, blindness, paralysis, and the effects of having part of their bowel removed.
How can you get VTEC?
VTEC are widespread in the environment and are present in healthy farmed, wild, and domesticated animals and birds and shed in their faeces. Cattle, sheep and goats are considered to be the main source among farmed animals.
Transmission to humans can occur as a result of direct contact with VTEC-contaminated faecal material, as a result of handling or petting animals or by exposure to faecally contaminated mud or vegetation during recreational activities. Exposure can also occur from consumption of water or food which is contaminated. Fruit and vegetables can be contaminated if they come in contact with soil, animal faeces or manure which contains VTEC. The use of contaminated water for irrigation of food crops and washing of fruit and vegetables has also been identified as a transmission route for VTEC. Food of animal origin may be contaminated during milking (milk and dairy products) or during the slaughter process (meat and meat products).
Transmission between people is another way that VTEC can be spread. The organism is found in the faeces of infected people and it can be passed from one person to another if hygiene or hand-washing habits are inadequate.
What can you do to prevent VTEC infection?
- Thoroughly cook meat which has been minced (e.g. beef burgers) diced, rolled and blade- or needle-tenderised, i.e. until the interior or core is no longer pink and the juices run clear
- When eating out, check beef burgers are thoroughly cooked
- Refrigerate or freeze all meat products immediately on returning from shopping
- Prevent cross-contamination. Never let raw meat, or its juices, come into contact with cooked meat or any other food that will not be cooked before eating
- Wash hands and utensils after contact with raw foods
- Wash fruit and vegetables with drinking water before eating
- Young children, the frail elderly, and those people suffering from chronic diseases or with weakened immune systems should avoid the following: raw milk and dairy products made from raw milk; rare or undercooked meats; fermented uncooked meats, e.g. some salamis; and unpasteurised juices (unless freshly prepared)
- Only consume water of drinking quality. Users of private wells should ensure that the well is protected against entry of surface run-off and access by animals and that any disinfection system in place is properly maintained. Any well water that changes colour or taste, particularly after heavy rainfall should, as a precaution, be boiled before use for drinking, preparing food, making ice, or brushing teeth
- Wash hands with warm soapy water after using the toilet, changing nappies, and before preparing food, especially between handling raw and ready-to-eat food and after petting animals
- Ensure that people with diarrhoea, especially children, wash their hands carefully with soap and warm water after going to the toilet, and that people wash hands after changing soiled nappies
- Anyone with a diarrhoeal illness should avoid preparing food for others, swimming in public pools or lakes and sharing baths with others
- The national recommendations by the Health Protection Surveillance Centre (HPSC) regarding exclusion from work of infected food handlers should be strictly followed
- Children who are still infectious should not be allowed back into crèches or other childminding centres until they are free of infection
- Wash hands thoroughly after contact with animals and animal faeces