[Epidemiological aspects of human herpesvirus 8 infection and of Kaposi's sarcoma]

HHV-8 belongs to the herpesviridae family, to the gammaherpesvirinae subfamily, and to the rhadinovirus genus. Whereas several viral homologues exist in non human primates, HHV-8 is the only rhadinovirus known in human. HHV-8 is mainly the etiological agent of the four clinico-epidemiological forms of Kaposi's sarcoma (classic, endemic, post-transplant, and epidemic/HIV associated). HHV-8 is not an ubiquitous virus. It is mainly endemic in areas of high endemicity for classic or endemic Kaposi's sarcoma including the Mediterranean area and most of East and Central Africa. Its prevalence varies in the adult population, from less than 5% in the USA and Northern Europe to more than 50% in some regions of the African continent and around 10 to 20% in Italy and Greece. One can estimate that several hundred million people are HHV-8 infected worldwide with at least 150 million on the African continent. Modes of infection seem different in low and highly endemic areas. In low endemic areas, HHV-8 is mainly present in the male homosexual population, where this herpesvirus is transmitted during sexual contacts. In contrast, in highly endemic areas, as Central Africa, HHV-8 transmission occurs mainly from mother to child and between siblings. Heterosexual transmission remains low as well as transmission through blood products. Saliva seems to play a major role in the viral transmission, and may be a reservoir for HHV-8.