Diarrhoea and sickness in children - Causes of gastroenteritis in children

Gastroenteritis is usually caused by a type of virus called a rotavirus, which infects a child's stomach and bowel. The virus is highly infectious and is often spread to other children as a result of poor hygiene.

The virus is passed out in the stools (faeces) of an infected child. It can be transferred to any surfaces, objects and food a child touches if they do not wash their hands after going to the toilet.

The infection can then be passed to another child who eats contaminated food, or touches a contaminated object or surface, and then touches their mouth.

Small droplets of infected faeces or vomit can also be carried in the air, which children can then breathe in.

Rotavirus infections are easily spread in this way, particularly among young children, who often forget to wash their hands after going to the toilet or before eating, and who have not built up a resistance to the infection yet. The virus can also survive for several days on surfaces or utensils.

This is why these types of infections often occur in places where there is a high number of young children, such as playgroups, nurseries and infant schools.

Rotaviruses affect the absorption of water from digested food into the body, which is why one of the most common symptoms of the infection is diarrhoea and why dehydration is a common complication.

Other causes

In a small number of cases, gastroenteritis in children may be caused by infections other than the rotavirus. These include:

• other viruses – such as the adenovirus or norovirus
• food poisoning – this is usually caused by eating food contaminated with bacteria such as salmonella or E. coli
• parasitic infections – such as giardiasis, which is usually picked up when travelling abroad