In some acute infectious diseases, the spleen 3 arterial capillaries ending in sinuses becomes congested and acutely enlarged: for example, in typhoid fever anthrax and infectious mononucleosis. In diseases associated with marked changes in the blood, such as leukaemia and malaria, it may become chronically enlarged. Rupture of the spleen may occur, like rupture of other internal organs, from extreme violence but in countries where many people have a greatly enlarged and soft spleen as the result of malaria, rupture occasionally occurs following even a light blow to the left side of the abdomen. It bleeds excessively when torn, so that this accident is generally followed by collapse, signs of internal haemorrhage and death if not dealt with promptly by operation.