There are three stages of the HIV infection, namely: acute infection, clinical latency, and AIDS.

Acute infection

This stage is typically within two to four (2 – 4) weeks from the day one acquires the HIV infection. Some people may feel sick with flu-like symptoms, and this is termed primary HIV infection or acute retroviral syndrome as the body naturally responds to the HIV infection.
During the acute infection stage, large amounts of HIV are being produced in the infected person’s body. The virus uses CD4 cells to make copies of itself and destroys the CD4 cells in the process, leading to a reduction in CD4 cell count. An infected person’s ability to spread HIV is highest during this stage as the amount of virus in the blood is very high.
In due course, the infected person’s immune response will begin to bring the amount of virus in the body back down to a stable level and the CD4 cell count will begin to rise, though it may not return to the levels before the infection.

Clinical latency (inactivity or dormancy)

This period is sometimes called asymptomatic HIV infection. In this stage, HIV is still active but reproduces at very low levels, and the infected person may not have any symptoms or get sick. Depending on various circumstances, the period in clinical latency stage varies from one infected person to the other. Towards the middle and end of this stage, an infected person’s viral load begins to rise, the CD4 cell count begins to drop and symptoms of HIV infection begin to manifest as the immune system becomes too weak to offer protection against diseases.

People who are on ART may live with clinical latency for several decades. While ART greatly reduces the risk of transmitting HIV, it is important to remember that an infected person may still transmit the virus.

AIDS (acquired immunodeficiency syndrome)

This is the stage of infection that occurs when an infected person’s immune system is greatly weakened, leading to vulnerability to infections often called opportunistic infections. Normal CD4 cell counts are between 500 and 1,600 cells per cubic millimetre (500-1600 cells/mm3). When the number of CD4 cells falls below 200 cells/mm3, an infected person is considered to have progressed to AIDS.

One can also be diagnosed with AIDS if he/she develops one or more opportunistic illnesses, regardless of the CD4 count. Without treatment, people who are diagnosed with AIDS survive for a very short time, and with a serious opportunistic infection, life expectancy without treatment is reduced to about a year. People with AIDS need medical treatment to prevent death.