Eight different herpesviruses infect people and cause some common viral infections. Herpesviruses establish a lifelong persistent infection in the host in an inactive (dormant or latent) state. Sometimes the virus reactivates and produces further episodes of disease.
Herpes simplex HSV 1, HSV 2, and varicella-zoster virus (HHV 3) infections present as blisters on the mucous membranes or skin. Infectious mononucleosis is the best-known disease caused by the Epstein-Barr virus (HHV 4), but EBV can also be involved in some cancers. Cytomegalovirus (HHV 5) causes serious infections in newborns or immunocompromised people. Human herpesviruses 6 and 7 (HHV 6 and HHV 7) cause roseola infantum infection in childhood. HHV 8 is associated with certain cancers in people with weakened immunity including AIDS patients.