Burkitt lymphoma is commonly associated with the infection of B cell lymphocytes with the Epstein–Barr virus (EBV) and in these cases in considered to be one form of the Epstein–Barr virus-associated lymphoproliferative diseases. The epidemic variant of Burkitt lymphoma (eBL) is in almost all cases associated with EBV infection. However, the sporadic variant, which afflicts ~1,200 individuals/year in the US, is associated with the virus in only 10-15% of cases. The immunodeficiency-associated variant of Burkitt lymphoma strikes 30-40% of individuals with HIV-induced AIDS and rare cases of patients who received a bone marrow or other organ transplant; in the latter cases, individuals have almost always received intensive chemotherapy and therefore are immunodeficient. About 30% of individuals with the immunodeficiency variant are infected with EBV. The fact that some Burkitt lymphoma cases do not involve EBV allows that many cases of the disease are not caused and/or promoted by EBV, i.e. the virus may be an innocent passenger virus in these cases. However, the almost ubiquitous presence of the virus in the epidemic variant of Burkitt's lymphoma suggests that it contributes to the development and/or progression of this variant. The mutational landscape in BL has recently been found to differ between tumors with and without EBV infection, further strengthening the role of the virus in lymphomagenesis.