To evaluate the pathogenic mechanisms and transmission routes involved in KSHV infection in 22 Cuban individuals who maintained close contact with epidemic KS patients, real-time PCR was used to quantify KSHV-DNA in clinical samples of plasma, saliva and peripheral blood mononuclear cells (PBMC). KSHV-DNA was detected in 72.7% (16/22) of the contacts. The highest levels of KSHV load were detected in saliva, followed by PBMC (average log copies/100 ng DNA = 1.28 and 1.12), while significantly lower levels were detected in plasma (average log copies/ml = 0.37). Two of three intra-domiciliary and two serodiscordant sexual contacts of AIDS-KS patients were infected with KSHV. The rate of KSHV-DNA detection in saliva and PBMC samples in men who have sex with men (MSM) was significantly higher than in heterosexuals (HT) (p = 0.014). MSM were more likely to harbor KSHV-DNA in saliva when compared with HT individuals (OR 4.33; 95% CI 1.117-16.8). These results emphasize that, in Cuba, KSHV horizontal transmission through saliva may occur, although homosexual behavior may predispose an individual to KSHV acquisition. Even in the absence of disease, KSHV could cause an asymptomatic systemic infection in individuals who maintain close contact with AIDS-KS patients.