The disease from the point of infection till the development of AIDS has a lot of intermediate stages. The stages are as follows:
First stage or Window Period
The first stage is called the window period which extends from six weeks to six months. It is the time interval existing between the time of infection when the virus enters one's body to the time when the patient develops enough antibodies to be measured on an HIV test.
Second stage or asymptomatic stage
The second stage is called the asymptomatic stage where the patient shows no sign of infection. This is because the immune system is strong in combating the virus.
Third stage or symptomatic stage
The third stage is called the symptomatic stage where he virus (HIV) becomes very active which in turn weakens the patient's immune system. In this stage symptoms of HIV infection may begin to appear.