There are several forms of Epstein–Barr virus (EBV) infection. These include asymptomatic infections, the primary infection, infectious mononucleosis, and the progression of asymptomatic or primary infections to: 1) any one of various Epstein-Barr virus-associated lymphoproliferative diseases such as chronic active EBV infection; 2) non-lymphoid cancers such as Epstein-Barr virus associated gastric cancer; and 3) Epstein-Barr virus-associated non-lymphoproliferative diseases such as some cases of the immune disorders of multiple sclerosis.