Primary Infection
The infected person will experience flu-like symptoms as the body begins to try to fight the infection. The immune system will produce antibodies to the HIV virus and killer T cells. In reaction to the infection within them, the helper T cells often commit suicide, a process called apoptosis.
Improvement
After the primary infection, HIV levels in the blood drop dramatically, though it is still active in the lymphoid organs. Helper T cell levels also jump to normal. The virus will remain hidden in the cells during this period, where the immune responses cannot reach it, and CD4+ T cell levels will continue to decline.
Deterioration
Eventually, helper T cell levels will drop too low and HIV levels will spike. Without the helper T cells to help coordinate immune responses, the immune system deteriorates dramatically. It is unable to fight off various opportunistic infections, which a healthy immune system would be able to deal with. These infections can become very severe and the person may develop various cancers. It is at this point in the progression of the disease, or when the helper T cell levels in the blood drop below 200 cells per cubic millimeter, that the infected person is diagnosed with AIDS.
An opportunistic infection is an infection that takes advantage of an HIV infected person's weakened immune system and attacks. According to the University of California San Francisco Medical Center, some of the opportunistic infections that are hallmarks of AIDS include:
- Hepatitis B and C viruses - These viruses can cause liver disease, one of the leading causes of death in AIDS patients
- Tuberculosis - TB, a bacterial infection, affects the lungs. It is more likely to be dangerous to those whose helper T cell levels are dangerously low.
- Candidiasis - This is a fungal infection that is very common in AIDS patients. Yeast growth causes white patches, most commonly in the mouth. This makes eating very difficult and painful, leading to a loss of appetite.
