Glossary of Terms :: HIV

Acquired Immune Deficiency Syndrome (AIDS)

AIDS is not a disease as such, but rather a group (syndrome) of specific illnesses and conditions that occur as a result of the damage caused to a person's immune system by HIV. Because an HIV positive person's immune system is impaired by HIV, certain opportunistic infections can flourish. These infections would not cause problems to a person with a fully functioning immune system. A person is said to have 'AIDS' when they have one or more of these opportunistic infections. Our positive page has more detailed information.

Antibodies

Antibodies are created by the body's immune system in response to any infections, viruses etc. If someone is infected with HIV they will create specific antibodies in response to the presence of HIV. The most common HIV test - the HIV antibody test - tests for the presence of antibodies to HIV in the immune system.

Human Immuno-deficiency Virus (HIV)

HIV is a retrovirus, and is unusual as it uses the cells of an infected person to make copies of itself. The way HIV works is still not fully understood, but is known to affect the immune system, preventing it from working properly. HIV infects several primary cells (CD4 and other lymphocyte cells) of the immune system which co-ordinate the body's fight against infection.

CD4 cells/ CD4 count

CD4 cells are cells which fight the HIV and through these the virus can be held at bay for many years. However, the virus is itself attacking these cells and eventually the number of CD4 cells decreases and the amount of virus increases. When the number of CD4 cells start to decline, the person becomes much more susceptible to other infections. A CD4 count will measure the number of these cells in the blood. The lower the CD4 count the more damage is being done to the body's immune system by the virus.

Combination Therapy

There is no cure for HIV. However, research has shown that taking a combination of anti-HIV drugs can slow down the damage done to the body by the virus. If successful, combination therapy can improve and sustain the health of someone with HIV and means they are less likely to develop what were previously known as 'AIDS-defining conditions'. The long term effects of these drugs are not yet fully understood and it is necessary to adhere 100% to the treatment in order for it to be successful. Combination therapy doesn't work for everyone.

Viral Load

This is the amount of HIV virus present in the blood. It is monitered regularly and the higher the viral load, the more virus there is in the blood. Sometimes the measurement will come back as 'undetectable.' This does not mean there is no HIV in the blood, but rather that there are too few particles to be detected by the test. This does not mean that the virus cannot be transmitted to someone else.

The Window Period (seroconversion)

When someone becomes infected with HIV it can take up to three months for their immune system to produce enough antibodies (see antibodies) to show up in a test. This gap is called the window period or seroconversion. Although there may not be enough antibodies to show up in a test during this period, if they are infected, there will be enough of the virus to infect someone else. Indeed, when someone is first infected with HIV the level of the virus in their body can get very high and therefore they may be particularly infectious at this time. It is also important to remember that if a person is exposed to the virus again in the three months whilst waiting to have the first test, they will have to wait another three months from that point of exposure in order for a second test to be completely accurate.