Primary stage

This is the first stage of HIV infection. It begins as soon as HIV gets into the blood and lasts from two to six weeks. HIV reproduces very fast, infecting and killing many CD4 cells. The levels of HIV in the blood (sometimes called the viral load) can get very high. Some people develop a flu-like illness during this period while others have no symptoms at all.

The number of CD4 cells drops for a while but returns to near-normal levels by the end of this stage. Normal CD4 cell counts are 400–1,500 in men, and 400–1,800 in women.