Dysentery is an intestinal infection that causes severe diarrhoea with blood in the stool. In some cases, mucus may also be found in the stool. This usually lasts for 3 to 7 days. Diarrhoea causes loss of body fluids which in turn results in loss of salts and minerals such as sodium, chloride, and potassium from the body. This leads to weakness in the body.