Prolonged incubation period of AIDS in intravenous drug abusers: epidemiological evidence in prison inmates.

Fourteen heterosexual inmates who developed acquired immunodeficiency syndrome (AIDS) while incarcerated in New York state prisons were studied. All 14 had regularly used illicit drugs intravenously in New York City prior to imprisonment. Leukocyte counts on admission to the state prison system--when all of these inmates were well--were depressed by one-third when compared with those in matched intravenous drug-using inmates used as controls (mean leukocyte counts, 4,430 vs. 6,320 cells/mm3, respectively; P less than .005); twelve (86%) of the 14 inmates who developed AIDS had counts of less than 5,000 cells/mm3, compared with only six (14%) of the 42 controls (P less than .00001). The 14 inmates developed AIDS symptoms a mean of 22.6 +/- 9.6 months after imprisonment. We conclude that leukopenia is frequently to be found in presymptomatic AIDS infection and that the minimum mean incubation period of AIDS in intravenous-drug abusers is quite prolonged.