Gastroenteritis is caused by an infection of the stomach and intestine. The infection interferes with one of the main functions of the intestines - the absorption of water and its distribution around the body.
This is why the most common symptoms of gastroenteritis are diarrhoea and vomiting; both of which are caused by the excess of unabsorbed fluids in the intestine.
It also explains why dehydration is such a common complication in gastroenteritis.
Some of the causes of gastroenteritis are discussed below.
Norovirus
Noroviruses are the most common cause of viral gastroenteritis in adults. They are sometimes called the 'winter vomiting disease' because people tend to get them during the winter months. However, noroviruses can occur at any time of the year.
Norovirus outbreaks are common, particularly within contained environments, such as hospitals, nursing homes, and schools. This is because the illness spreads very easily from person to person, and the virus can survive for several days in a contaminated area.
Noroviruses can be spread through:
- contact with an infected person,
- contact with surfaces, or objects, that are contaminated with the virus, or
- by eating, or drinking, contaminated food, or water.
There are many different types of norovirus, and it is possible for infection to occur several times. This is because after getting the illness, immunity to the virus only lasts for 14 weeks.
Food poisoning
Most cases of bacterial gastroenteritis are caused by food poisoning, although in some cases, food poisoning can also lead to viral gastroenteritis.
Food can become contaminated with bacteria in several different ways. Contamination can occur if:
- meat is not properly cooked,
- foods are not properly stored and refrigerated - particularly meat, eggs, and dairy products,
- food is washed in dirty water, and
- food is handled by somebody with a bacterial infection who has not washed their hands after going to the toilet.
If you suspect that you have contracted food poisoning while eating at a public restaurant, or takeaway, you should inform your local authority. Reports should be made to your local council's Environmental Health Office.
Contaminated water
Drinking water that has been contaminated with human, or animal faeces, can cause gastroenteritis. This is less of a risk in the UK, and other developed countries, compared with other parts of the world, such as Africa and South Asia. However, you should always take bottled water supplies, or water purification equipment, with you if you are camping, or travelling, in this country and do not have access to tap water.
Antibiotics
In some circumstances, certain antibiotics can kill off the so called 'friendly bacteria' that live in your stomach and intestine. This can leave you vulnerable to infection from other types of bacteria that can cause gastroenteritis.
Gastroenteritis that is caused by taking antibiotics is known as antibiotic-associated gastroenteritis.
Antibiotic-associated gastroenteritis is normally mild, and the symptoms should pass within a few days.
'Traveller's diarrhoea''
Traveller's diarrhoea' is a term that is sometimes used by health professionals to refer to gastroenteritis that is contracted when you are travelling in a foreign country. It is particularly common in countries with low standards of public hygiene. It can be caused by consuming contaminated food, or water. However, most cases are mild and should pass within a few days.
