For several years after seroconversion, people with HIV infection feel good. Because they have no symptoms of the infection, this period is called the asymptomatic (meaning “no symptoms”) period. During this period the person will be unaware of the HIV infection unless a blood test shows antibodies to HIV. About 70-80 percent of the people who presently have HIV infection are in this asymptomatic period.
The length of time people remain in the asymptomatic period is highly variable. The average is five to eight years until the symptoms of HIV infection appear, and eight to ten years until AIDS is diagnosed. The shortest time, two years or less from infection until the development of AIDS, is highly unusual. Most people stay asymptomatic for five years or more. Based on four different studies (done before any effective treatment was available), the time lapse between transmission of HIV and AIDS is as follows: After 1 year, 0 percent of the people with HIV infection were diagnosed with AIDS; after 2 years, 0 percent; after 3 years, 3 percent; after 4 years, 6 percent; after 5 years, 12 percent; after 6 years, 20 percent; after 7 years, 27 percent; after 8 years, 36 percent; after 9 years, 45 percent; after 10 years, 53 percent.
The reasons for this great variation are unknown. We know that treatment makes a decisive difference in the rate of the infection’s progression. We would like to think that “wellness”—a psychological sense of well-being, good nutrition, exercise programs, and other general health measures—increases the length of the asymptomatic period, although we don’t know that.
Other factors may contribute to the length of the asymptomatic period but are beyond the control of the person with HIV infection. One of these factors is the inoculum size, or number of viruses when infection took place: the lower the inoculum size, the slower the infection
progresses. Another factor is the specific strain of the virus: some strains of HIV seem to cause the infection to progress faster. A third factor is the age of the person infected: the infection progresses much faster in children and somewhat faster in older people. The final factor is the genetic makeup of the person infected: some people seem to have genes that make them prone to faster progression of the infection.
The presumed reason for the long delay before symptoms appear is the body’s enormous number of CD4 cells (the white blood cells that help the immune system and that the virus infects). At first, the virus infects only a relatively small number of CD4s, then more and more of them, but the process is slow. Several years go by before the body loses so many
CD4s that the immune system cannot defend itself against other infections. Most people lose about 80 to 90 percent of their CD4s before AIDS develops.
*40\191\2*