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Objectives: To evaluate if different levels of human herpesvirus 6 (HHV-6) antibodies can predict HIV disease progression. Design: Longitudinal study of individuals with a documented date of HIV seroconversion. Setting: Clinical centers located throughout Italy. Patients: Individuals who serconverted for HIV between 1983 and 1995 in Italy. Methods: Sera were tested for IgG antibodies to HHV-6 using a commercial enzyme immunoassay. A serum sample with an optical density (OD) ≥ 242 (i.e. the mean value of 10 negative controls+ 4×standard deviation) was considered as HHV-6 positive; the progression of HIV disease was evaluated estimating the relative hazards (RH) of AIDS (by Cox models) for individuals with higher levels vs. lower levels of HHV-6 antibodies or considering levels of antibodies based on 10% increase of the distribution (deciles). Rates of CD4 decline fitting linear regression were also estimated. Results: A total of 381 persons were followed for a median time of 4 years (range: 0.15–9 years) following the date of collection of the serum sample. The median OD value of HHV-6 antibodies was 306, with an interquartile range of 241–440 and a range of 48–2330. A slight inverse correlation was found between HHV-6 antibody levels and age of the individual at the time of serum collection (Spearman rank correlation coefficient, −0.16; p = 0.0013). No association was found between HHV-6 and CD4 level or between HHV-6 and CD8 level at the date of serum collection. The unadjusted RH of progression to AIDS was 0.63 (95% CI: 0.42–0.96) for HHV-6 positive individuals vs. HHV-6 negative; when adjusting for possible confounders (CD4, age, pre-AIDS HIV-related pathologies at the date of sera collection, and previous anti-herpes treatment), the RH of AIDS increased to 0.80 (95% CI: 0.51–1.23). No particular association with HIV disease progression was found when using the deciles of the distribution of HHV-6 antibodies. The median CD4 cell loss was 5.0 × 106 cells/l per month among HHV-6 positive individuals and 5.7 × 106 cells/l per month among the others. Conclusions: The presence of high levels of HHV-6 antibodies does not seem to predict the clinical or immunologic progression of HIV disease.

To evaluate risk factors for HIV encephalopathy and whether Kaposi's sarcoma (KS) and coinfection with human herpesvirus 8 (HHV-8) protect against this disease in a cohort of HIV seroconverters.

Two surveys were conducted in 1990 and 1991 in order to estimate the prevalence of HIV infection among injecting drug users attending drug treatment centers throughout Italy. Among the 35,073 IDUs attending these facilities in 1990, 32.I% were HIV-positive. In 1991, 29.7% of 41,794 IDUs were HIV-positive. HIV prevalence was higher among prior attendees compared to new entrants (38.0% vs. 20.5% in 1990, and 35.8% vs. 16.6% in 1991); prevalence was also higher among females. These findings suggest that HIV prevalence among Italian drug users is slowly declining.