Enzootic bovine leukosis (EBL) is a significant disease of cattle worldwide, characterized by the development of tumors on lymphatic tissues (lymphosarcoma) throughout the body, such as the spleen, thymus and lymph nodes. It is caused by bovine leukemia virus (BLV), a malignant B cell lymphoma. Clinical signs of EBL vary depending on the location of where tumors develop and the severity and stage of progression.
Less than 1% of cows infected with BLV develop lymphosarcoma, and one-third of cattle infected with BLV develop persistent lymphocytosis.
BLV is transmitted to cows through blood transfer, through the placenta during pregnancy and by consumption of colostrum or milk from BLV-infected cattle.