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.