AIDS stands for "Acquired Immunodeficiency Syndrome" , which is an illness caused by HIV (Human Immunodeficiency Virus). The virus enters a person’s body and attacks a key part of the immune system -- T cells or CD4 cells, which fight off infections and diseases. HIV invades T-cells and gradually weakens the immune system to the point that the HIV infected person can no longer fight against infections. When an HIV infected person develops diseases because of weakened immunity, the disease is called AIDS.
HIV can be transmitted through blood and blood products. It can also be found in semen, pre-seminal fluid (pre-cum), vaginal fluids, and breast milk of an infected person.
HIV gradually destroys CD4T-lymphocyte, one important type of white blood cell, which plays a vital role in the body immune defence system. The CD4 count correlates closely with the immune defence status and falls as the disease progresses. People infected with HIV need to have regular follow up and blood tests to assess disease progression by monitoring the amount of virus in the blood (viral load) and CD4. These indexes provide doctors with useful information to monitor HIV disease progression status and a person’s response to treatment.