Diseases like typhoid or cholera infect the intestines and cause diarrhoea.The frequent production of watery faeces results in excessive fluid being lost from the body as not enough water is reabsorbed by the large intestine.This can lead to death, especially in the very young.Diarrhoea may be caused by damage to the epithelial cells, loss of microvilli due to toxins or a decrease in the water potential in the lumen due to toxins such as cholera toxin.Treatment is by oral rehydration therapy. Water and electrolytes are replaced by a drip or a rehydration solution containing glucose, sodium, potassium and other electrolytes.Sodium ions are absorbed by alternative pathways and alternative sodium-glucose carrier proteins are used.