Kaposi's sarcoma associated with previous human herpesvirus 8 infection in kidney transplant recipients.

This study investigates the prevalence of human herpesvirus 8 (HHV-8) infection in kidney transplant patients, evaluating the risk of HHV-8 transmission via transplantation and the association between pre- and posttransplantation HHV-8 infection and the subsequent development of Kaposi's sarcoma (KS). Immunofluorescence and an enzyme immunoassay were used to determine HHV-8 seroprevalence in 175 patients awaiting kidney transplantation and 215 controls who were attending our clinic for other reasons. All patients in the study came from central or southern Italy. Seroprevalence was similar in both groups (14.8 versus 14.9%), with no significant difference between the rates for male and female patients. Of the 175 patients, 100 were tested for anti-HHV-8 antibodies at various times during follow-up. During follow-up, seroprevalence increased from 12% on the date of transplantation to 26%. This increase was paralleled by an age-related increase in seroprevalence in the control group. During follow-up from 3 months to 10 years after transplantation, KS was diagnosed in seven patients (4.0%). Six of these patients were positive for HHV-8 prior to transplantation. Overall, 23.0% of patients who were HHV-8 positive before transplantation developed KS, whereas only 0.7% of seronegative patients developed the disease (relative risk, 34.4; 95% confidence interval, 4.31 to 274.0). This finding suggests that the key risk factor for KS is infection prior to transplantation and that antibody detection in patients awaiting transplantation could be useful in identifying patients at high risk for KS. In patients from geographic areas with a high prevalence of HHV-8, serological tests on donors may be less important.