Oral hairy leukoplakia is caused by?

Hairy leukoplakia is a white patch on the side of the tounge with a corrugated or hairy appearance. It is seen in severe defects of immunity, paicularly in HIV infection. The cause of this condition is an oppounistic infection by Epstein Barr virus. Epstein-Barr virus (EBV) infections in the oral cavity may present as a primary infection (infectious mononucleosis). Hairy leukoplakia is an unusual presentation of recrudescent EBV in the oral cavity, where this normally lymphotropic virus is present within the epithelium. In patients with established HIV/AIDS, hairy leukoplakia is usually associated with a low CD4 count and high viral load. Ref: Woo S. (2012). Chapter 76. Biology and Pathology of the Oral Cavity. In L.A. Goldsmith, S.I. Katz, B.A. Gilchrest, A.S. Paller, D.J. Leffell, N.A. Dallas (Eds), Fitzpatrick's Dermatology in General Medicine, 8e.