Glossary

• Human because this virus can only infect human beings.
• Immuno-deficiency because the effect of the virus is to create a deficiency, a failure to work properly, within the body's immune system.
• Virus because this organism is a virus, which means one of its characteristics is that it is incapable of reproducing by itself. It reproduces by taking over the machinery of the human cell.

Human Immuno-deficiency Virus (HIV) is the virus that causes AIDS. 

HIV attacks your immune system. Immune systems are made up of cells that fight infection and disease. One of the most important of these cells that fights infection is called the CD4 cell. It is also called the "T-helper cell" or T-cell.

• Once HIV is in the body, it infects CD4 (T-cell) cells and makes copies of itself in these cells. This makes new viruses. These new viruses are let out into the blood and infect other CD4 (T-cell) cells. This process kills the CD4 (T-cell) cells and the CD4 (T-cell) count goes down.
• As CD4 (T-cell) cells are lost, the immune system becomes weak. This makes it harder for your body to fight certain conditions that do not affect most healthy people. These include opportunistic infections (OIs) such as pneumonia, herpes, tuberculosis, and cancers such as lymphoma and cervical cancer.