Thrombosis and encephalomalacia in a case of turning sickness

Abstract

Turning sickness or cerebral theileriosis is an uncommon aberrant form of infection by Theileria parva or Theileria taurotragi in which lymphoblasts parasitized by schizonts accumulate in cerebral vessels leading to thrombosis and infarction. In the more acute form areas of intense congestion and haemorrhage are present in the meninges and brain which are associated with areas of softening (Infarction) and discoloration of brain tissue. Thrombosed meningeal vessels are often very promiment. There may be severe haemorrhage into the ventricles. Histological examination shows the obstruction of arteries and arterioles by large numbers of parasitized lymphoblasts associated with haemorrhage and encephalomalacia. Similar lesions may occur in the spinal cord and infarcts may be present in the spleen.