Persistent lymphocytosis is defined by an increase in total lymphocyte count by 3 times the normal standard deviation above normal, persisting for at least three months with no clinical signs of neoplastic lesions. This is thought to represent 1/3 of all BLV infected cattle. | Persistent lymphocytosis is defined by an increase in total lymphocyte count by 3 times the normal standard deviation above normal, persisting for at least three months with no clinical signs of neoplastic lesions. This is thought to represent 1/3 of all BLV infected cattle. |