1. The body’s immune system develops antibodies to fight various virus and bacteria that invade the body.
2. The presence of particular antibodies in a person’s blood indicates that the person has been exposed to that infection. For example. When a blood test revels that the antibodies to HIV are present in the blood, it means that the person is infected with HIV.
3. The “Window period” is the time during which measurable amounts of antibodies against HIV infection have not yet developed even though the person has HIV infection .This period is usually 2-12 weeks, in rare instances it may be longer.
4. This means that if an HIV antibody test ( for example ELISA) is taken during the window period it will be negative since the blood test is looking for antibodies that have not yet developed . But that person is already HIV infected and can transmit blood to others.
