What is AIDS

People have been warned about HIV and AIDS for over twenty years now. AIDS has already killed millions of people, millions more continue to become infected with HIV, and there's no cure – so AIDS will be around for a while yet.

AIDS is one of the biggest problems facing the world today and nobody is beyond its reach. Everyone should know the basic facts about AIDS.

What is AIDS?

AIDS is a medical condition. People develop AIDS because HIV has damaged their natural defences against disease.

What is HIV?

HIV (Human Immunodeficiency Virus)

HIV is a virus. Viruses infect the cells that make up the human body and replicate (make new copies of themselves) within those cells. A virus can also damage human cells, which is one of the things that can make a person ill.

HIV can be passed from one person to another. Someone can become infected with HIV through contact with the bodily fluids of someone who already has HIV.

HIV stands for the 'Human Immunodeficiency Virus'. Someone who is diagnosed as infected with HIV is said to be 'HIV+' or 'HIV positive'.

Why is HIV dangerous?

The immune system is a group of cells and organs that protect your body by fighting disease. The human immune system usually finds and kills viruses fairly quickly.

So if the body's immune system attacks and kills viruses, what's the problem?

Different viruses attack different parts of the body - some may attack the skin, others the lungs, and so on. The common cold is caused by a virus. What makes HIV so dangerous is that it attacks the immune system itself - the very thing that would normally get rid of a virus. It particularly attacks a special type of immune system cell known as a CD4 lymphocyte.

HIV has a number of tricks that help it to evade the body's defences, including very rapid mutation. This means that once HIV has taken hold, the immune system can never fully get rid of it.

There isn't any way to tell just by looking if someone's been infected by HIV. In fact a person infected with HIV may look and feel perfectly well for many years and may not know that they are infected. But as the person's immune system weakens they become increasingly vulnerable to illnesses, many of which they would previously have fought off easily.

The only reliable way to tell whether someone has HIV is for them to take a blood test, which can detect infection from a few weeks after the virus first entered the body.

When HIV causes AIDS

A damaged immune system is not only more vulnerable to HIV, but also to the attacks of other infections. It won't always have the strength to fight off things that wouldn't have bothered it before.

As time goes by, a person who has been infected with HIV is likely to become ill more and more often until, usually several years after infection, they become ill with one of a number of particularly severe illnesses. It is at this point in the stages of HIV infection that they are said to have AIDS - when they first become seriously ill, or when the number of immune system cells left in their body drops below a particular point. Different countries have slightly different ways of defining the point at which a person is said to have AIDS rather than HIV.

AIDS (Acquired Immune Deficiency Syndrome) is an extremely serious condition, and at this stage the body has very little defence against any sort of infection.

How long does HIV take to become AIDS?

Without drug treatment, HIV infection usually progresses to AIDS in an average of ten years. This average, though, is based on a person having a reasonable diet. Someone who is malnourished may well progress to AIDS and death more rapidly.

Antiretroviral medication can prolong the time between HIV infection and the onset of AIDS. Modern combination therapy is highly effective and, theoretically, someone with HIV can live for a long time before it becomes AIDS. These medicines, however, are not widely available in many poor countries around the world, and millions of people who cannot access medication continue to die.