Epstein-Barr virus and associated diseases.

The Epstein-Barr virus (EBV) is an ubiquitous virus infecting nearly the entire adult human population. The EBV is closely associated with rhinopharyngeal cancer in Southern China and Northern Africa. Three geographic subtypes of EBV have been identified to date. They differ by their nuclear antigene EBNA2. The EBNA2 AC strains predominate in Asia; EBNA2 AD strains predominate in the United States; EBNA2 B strains have all been identified in black Africa. Burkitt's lymphoma is the most frequent tumor in children aged 5 to 9 years in equatorial Africa. A prospective study in 42000 children in Ouganda demonstrated that children who develop Burkitt's lymphoma have severe EBV infection during the first months of life. Very early EBV infection observed in North or equatorial Africa increases the risk of Burkitt's lymphoma by 20-times that in Europe. Hyperendemic malaria observed in the equatorial zone increases the incidence of tumors by a factor of 20. An association between EBV and rhinopharyngeal cancer Is a constant feature only in South China, in North and East Africa, as well as in arctic regions as cases of carcinoma not associated with EBV infection have been reported in Greece. Surveys in the Democratic Republic of China concerning several hundred thousand persons have shown that serum IgA/VCA allows early diagnosis of cancer. It is estimated that the risk of rhinopharyngeal cancer is 20% in Chinese with high levels of IgA/VCA.