Epstein-Barr Virus (EBV) is the virus that causes mononucleosis, also known as “mono”. Almost all adults have had EBV. For most people, EBV never causes a health problem. However, when their immune system is not working properly (like people who have had a transplant and must be on medications that suppress their immune system), EBV can cause certain diseases where cells grow abnormally. EBV-associated Post-Transplant Lymphoproliferative Disease (EBV-PTLD) is a condition that can occur after a solid organ transplant (SOT) where EBV infects immune cells in your blood, called B...