HIV: Stages of Infection - Topic Overview
The U.S. Centers for Disease Control and Prevention (CDC) classify HIV infection into four stages.1
Stages of HIV infection
- Stage 1: There are no AIDS-related conditions AND the CD4+ cell count is greater than 500 or the percent of CD4+ cells is at least 29% of all lymphocytes.
- Stage 2: There are no AIDS-related conditions AND the CD4+ cell count is 200 to 499 or the percent of CD4+ cells is 14% to 28% of all lymphocytes.
- Stage 3: The CD4+ cell count is lower than 200, the percent of CD4+ cells is less than 14% of all lymphocytes, or an AIDS-related condition is present.
- Stage unknown: No information is available on the CD4+ cell count or the presence of AIDS-related conditions.
In general, the higher the CD4+ count, the less likely it is that opportunistic diseases will occur. Most people who have untreated HIV experience a gradual drop in the number of CD4+ cells. Each person responds uniquely to this decline.
CD4 cells are a type of white blood cell that fights infection. Another name for them is T-helper cells. CD4 cells are made in the spleen, lymph nodes, and thymus gland, which are part of the lymph or infection-fighting system. CD4 cells move throughout your body, helping to identify and destroy germs such as bacteria and viruses. The CD4 count measures the number of CD4 cells in a sample of your blood drawn by a needle from a vein in your arm. Along with other tests, the CD4 count helps tell...
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