Incubation period of AIDS in San Francisco.

In a closed population, the distribution of AIDS diagnoses over time is the convolution of the distributions of human immunodeficiency virus (HIV) infections and the incubation period. This has motivated estimates of the infection distribution, assuming known diagnosis and incubation distributions, but the usefulness of this method is limited by uncertainty about incubation. The large amount of information on the distribution of HIV infections in San Francisco's gay community suggests the opposite approach--estimating the incubation distribution, assuming known infection and diagnosis distributions. A non-parametric implementation of this strategy produced an estimate with a median at 9.8 years, increasing hazard rates, and less uncertainty than previous estimates.