Other forms of the herpes virus cause chicken pox, shingles, cold sores and genital herpes. Like other opportunistic infections, HHV-8 infection alone generally does not cause disease in healthy hosts. Coincident immunosuppression as a result of advancing age, AIDS, or organ transplantation is usually required before disease is manifested, and each of these conditions has become increasingly prevalent over the past several decades. All forms are characterized by HHV-8 infection and probably represent the same pathogenic process. Unlike most herpesviruses, HHV-8 is not ubiquitous.
Infection is uncommon in most of Asia, North America, and northern Europe.
Some areas, such as Sicily and the Po Valley in Italy, have long had elevated rates of Kaposi's sarcoma in the absence of HIV infection, and these regions have recently been shown to be hot spots for HHV-8 infection. These few facts explain the modern medical mystery of the evolution of AIDS-associated Kaposi's sarcoma. For a number of years, Kaposi's sarcoma in patients with AIDS was thought to be due to the HIV infection itself or to cytokines induced by the virus. However, careful epidemiologic studies by Beral et al. The emergence of HHV-8 as a pathogen during the AIDS epidemic results from the fact that it shares with HIV some of the same risk factors for transmission.