A survey for antibodies to a recombinant small viral capsid antigen (sVCA) of human herpesvirus type 8 (HHV‐8) was conducted in Sardinia, one of the world's highest incidence areas for classic Kaposi's sarcoma (KS). Prevalence of antibodies to HHV‐8 sVCA was greatest in patients with KS (95%), followed by family members (39%) and a Sardinian control population age‐ and sex‐matched to the relatives (11%). Within families, prevalence of antibodies was about equal among spouses, children, and siblings of KS patients, a finding that raises the possibilities of intrafamilial person‐to‐person or vertical transmission. Antibodies were detected 2–3 times more frequently in males than in females. The data show that prevalence of antibodies to HHV‐8 sVCA correlates with the distribution of classic KS in a high‐ incidence area. Clustering of seroprevalence within some families suggests the presence of familial risk factors for active HHV‐8 infection
