1 What is AIDS?

Acquired immunodeficiency syndrome (AIDS) is a set of symptoms that indicate a person has become infected with a virus that has seriously damaged the body’s immune system. A key symptom is the development of one or more of a range of ‘opportunistic’ diseases.

2 And what is HIV?

AIDS is caused by HIV–the human immunodeficiency virus. HIV attacks the body’s immune system, especially CD4 cells (also known as T-cells) which help fight infections. HIV invades these cells and tricks them into reproducing copies of the AIDS virus.

3 How does the virus work?

Eventually the virus destroys the [CD.sub.4] cell. The HIV ‘copies’ then find more CD4 cells to attack. Finally, so many CD4 cells are destroyed that the immune system breaks down leaving it defenceless against deadly invaders. Today there are sophisticated means of measuring damage to the immune system. One of them is your CD4 cell count. The average healthy person has count of 800 to 1500. A person who is HIV positive (or seropositive) will have a much lower count, usually 500 or less.

4 How do you get it?

You can only become infected if your blood, comes in contact with the HIV virus. It is carried in some (but not all) bodily fluids, including blood, semen, vaginal secretions and breast milk. Most people get HIV in one of three ways: having unprotected sex with an infected person; injecting drugs with a needle that’s been used by an infected person; or being born to a mother who’s already infected. You can also contract HIV by receiving infected blood or blood products, a big problem still in countries like China.

5 What, does it do?

HIV batters the body’s defences until diseases which the immune system normally fends off become major threats. The virus may lie dormant for years before symptoms appear. There are more than 25 ‘opportunistic infections’ (also called AIDS-defining illnesses). These include PCP (an infection which attacks the lungs and breathing passages); pneumonia, tuberculosis and MAC (a bacterial infection) which causes fever, weight loss, loss of appetite and diarrhea. Common fungal infections include oral thrush, meningitis and histoplasma capsulatum which can attack the central nervous system.