Rotavirus

Rotavirus is a virus that causes diarrhoea. Most of the time only children who are younger than five years old get the disease. The signs of the disease are severe diarrhoea and vomiting, which start suddenly and last for two or three days. Rotavirus also causes diarrhoea in animals. A vaccine, which prevents children from getting the disease is available in many countries.
Like most viruses, rotaviruses are made from RNA and protein. The RNA carries the genes that are used to make more rotaviruses. They are called rotaviruses because they sometimes look like little wheels and "rota" is the latin word for "wheel". Rotaviruses get into the body through the mouth and are not present in the air unlike the viruses that cause colds. The disease is often spread by dirty hands and things used for cooking, but the viruses can dirty water. Rotaviruses are very small. They are a lot smaller than bacteria and can only be seen using an electron microscope. 
Children who have not been vaccinated usually get infected more than once. But when children are about five years old they are usually immune and cannot get it any more. This is because their bodies have become resistant to the viruses.
Rotaviruses infect the cells that the small intestine is made from. This makes it difficult for the body to digest food. Children usually make a complete recovery from the infection. But it is very important to make sure they drink enough water to replace what they are losing. In many countries the medicine used is called "oral rehydration solution". This comes in a small packet that is added to drinking water. It contains salt and sugar, which helps the body take up the water.
Rotaviruses were discovered in the 1970s. Since then doctors and scientists have shown that they are a problem to children all over the world. More than 500,000 children die from rotavirus infection each year and almost two million more become severely ill. The Bill &amp; Melinda Gates Foundation are helping to pay for rotavirus vaccines in countries that cannot afford to buy them. Between 2006 and 2011 it gave more than 82 million US dollars.