Infection

AIDS is the result of HIV, a retrovirus that only infects vital organs of the immune system (like CD4+T cells). HIV destroys CD4+T cells directly and indirectly. For the immune system to work properly, it needs CD4+T cells. After HIV leaves only 200 cells per blood drop, cellular immunity is lost, and AIDS is aquired.

When there are no antiretroviral drugs available, the average time progression from HIV to AIDS is 9 to 10 years. After that, average survival time is 9 months. The rate of infection, however, varies between the person, some taking just 2 weeks, others taking up to 20 years. Also, there are many factors which affect the rate of progression, which includes the general immune function. The immune system is stronger in young people and weaker in older people, and thus have a greater risk of rapid progression of the disease. Other coexisting infections such as tuberculosis and little-to-no access of health care may increase the progression of the disease. (HIV-1)