Incubation time of AIDS: progression of disease in a cohort of HIV-infected homo- and bisexual men with known dates of infection.

The time from infection with HIV to symptoms and AIDS is an important parameter in describing the natural course of HIV infection. We here describe disease progression in a group of 389 homo- and bisexual men. Of these 102 had known dates of infection, and during an average follow-up time of 31 months (range 2-108), 28 of these progressed from being symptom-free (CDC group II and III) to having some symptom from CDC group IV; 7 progressed to AIDS. By life-table analysis, the estimated average time from seroconversion to first symptom is approximately 5 years and to AIDS approximately 8 years. Very few patients are diagnosed with AIDS the first 2 years after infection, but after that the risk seems to be 5-10% per year. Increasing use of anti-HIV medication will render studies of this kind difficult in the future.