What causes gastroenteritis?
Gastroenteritis is an infection of the gut (intestines). The severity can range from a mild tummy (abdominal) upset for a day or two with mild diarrhoea, to severe diarrhoea and being sick (vomiting) for several days or longer. Many germs (viruses, bacteria and other microbes) can cause gastroenteritis.
A virus is the most common cause of gastroenteritis. For example, infection with noroviruses and adenoviruses are common causes of gastroenteritis in adults in the UK. However, other viruses can also be the cause. Viruses are easily spread from one person to another by close contact. This is often because of the virus being present on people's hands after they have been to the toilet. Surfaces or objects touched by the infected person can also allow transmission of the virus. The virus can also be passed on if the infected person prepares food. Outbreaks of a virus causing gastroenteritis in many people can occur - for example, in schools, hospitals or nursing homes.
Food poisoning from eating food infected with microbes causes some cases of gastroenteritis. Many different types of microbes can cause food poisoning. Common examples are species of bacteria called campylobacter, salmonella and Escherichia coli (usually shortened to E. coli). Poisons (toxins) produced by bacteria can also cause food poisoning. Another group of microbes called parasites can also be a cause. Water contaminated by bacteria or other microbes is another common cause, particularly in countries with poor sanitation. See separate leaflet called Food Poisoning in Adults for more details.
How is gastroenteritis diagnosed?
Most people with gastroenteritis recognise this from their typical symptoms and they do not usually need to see a doctor or to seek medical advice. Symptoms are often quite mild and commonly get better within a few days without any medical treatment.
However, in some circumstances, you may need to see a doctor when you have gastroenteritis. The doctor may ask you questions about recent travel abroad, if you have been in contact with someone with similar symptoms, or if you have recently taken antibiotic medication or been admitted to hospital. This is to look for possible causes of your gastroenteritis. The doctor will also usually check you for signs of lack of fluid in the body (dehydration). They may check your temperature, pulse and blood pressure. They may also examine your tummy (abdomen) to look for any tenderness
Tests are not usually needed. However, if you are particularly unwell, have bloody stools (faeces), have recently travelled abroad, are admitted to hospital, or your symptoms are not getting better, your doctor may ask you to collect a stool sample. This can then be examined in the laboratory to look for the cause of the infection
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- Freeman MC, Stocks ME, Cumming O, et al; Hygiene and health: systematic review of handwashing practices worldwide and update of health effects. Trop Med Int Health. 2014 Aug 19(8):906-16. doi: 10.1111/tmi.12339. Epub 2014 May 28.
- Acute diarrhoea in adults: racecadotril; NICE Evidence Summary New Medicine, March 2013
- Gastroenteritis; NICE CKS, July 2015 (UK access only)
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