NCI is collaborating with investigators at the Uganda Virus Research Institute and the Center for Disease Control and Prevention in Uganda to explore transmission routes for human herpesvirus-8 (HHV8). Infection with HHV8 is necessary for Kaposi Sarcoma (KS) to occur, and HHV8 prevalence varies dramatically across Africa, suggesting that cofactors correlated with geographic or environmental characteristics may influence risk of infection with the virus. Investigators have found that HHV8 transmission in blood is inefficient, but it does occur. They have documented that levels of HHV8 are considerably higher in saliva than in blood, a finding that adds support to a mechanism of salivary transmission from mother to child or from child to child. Further studies are being conducted across Uganda to assess small-area variation of HHV8 and to identify sociodemographic and environmental risk factors for HHV8 and KS. An investigation of the prevalence of HHV8 viremia and associated co-factors is also ongoing.