What does AIDS mean?

• AIDS stands for Acquired Immune Deficiency Syndrome.
• Acquired means you catch it.
• Immune Deficiency means a weakness in the body's system that fights disease.
• Syndrome means a group of health problems that make up a particular disorder.

What causes it?
When the human immunodeficiency virus (HIV) infects the body, it attacks CD4+ cells, also called 'T-helper cells', which are a fundamental part of our immune system. The HIV virus takes over the genetic material of these cells and instructs them to make more HIV viruses. The newly formed viruses break free, destroying the host cell in the process, and go on to infect and destroy other CD4+ cells. Over a period that may last from a few months up to 15 years, HIV destroys so many CD4+ cells that the immune system can no longer work properly. This leaves the body open to a whole series of infections that it would normally be able to fight off. It is these infections that eventually kill someone who has AIDS.

How do people get HIV?
The most common way of getting HIV is by having unprotected sex with a partner who is already infected. Drug users who share needles are also at risk, as is anyone who is accidentally pricked by a hypodermic needle that has been in contact with infected blood. The virus can also be passed from an infected mother to her baby: in the womb, during birth or through breast-feeding. In the developing world, a lack of sterile instruments and needles during medical procedures can be a problem, as can contaminated blood products.

You cannot get HIV by talking to, touching, hugging or kissing someone who is infected. However, oral sex is considered risky because the virus can pass from sexual fluids into the blood stream through small cuts and sores in the gums and in and around the mouth.

What happens when people get HIV?
The effect of HIV is different for everyone who is infected. At first, people may not know they are infected. This poses a particular problem because they can still be passing the virus on to others. Even if they have been in a risky situation and have taken an HIV test, it can be weeks or even months before the test will confirm whether or not they are HIV positive. This is because the test measures antibodies to HIV in the blood, and it takes time for the body to produce these antibodies.

Initially, many people suffer a short, flu-like illness, with fever, headache, sore muscles and joints, stomach ache, swollen lymph glands or a skin rash which lasts for one or two weeks. Some people have no symptoms at all at this stage. They then may remain well for years, depending on factors such as where they live and the availability of drug therapies. During this time, there is no way another person can tell if the person is HIV positive unless the person tells them. This is why practising safe sex is so important.

Without treatment, the CD4+ cell count usually goes down, and people begin to experience fevers, night sweats and diarrhoea, swollen lymph nodes, skin infections and weight loss.

When does HIV become AIDS?
HIV becomes AIDS when the immune system is so damaged that it can't fight opportunistic infections. Examples of these are: pneumocystis carinii pneumonia (a lung infection), Kaposi's sarcoma (a skin cancer), cytomegalovirus (which affects the eyes), and candida (a fungal infection that can cause thrush, or infections in the throat or vagina). The AIDS syndrome also includes neurological problems, dementia and brain tumours.

Is there any cure for HIV and AIDS?
Although a number of new drugs have improved the health, and extended the lifespans, of people infected with HIV, there is still no cure, and AIDS eventually causes death. The drugs currently in use are expensive and therefore not readily available in developing countries. Consequently, the life expectancy of people with AIDS in such locations is usually much shorter than it is in industrialised nations.

Where did AIDS begin?
Some scientists believe the virus came from chimpanzees in Africa in the 1950s, but no one is quite sure how it passed to humans. Little was known about it until the early 1980s. Since then it has become a global epidemic, and developing nations have been particularly affected.

Why is AIDS such a problem in Africa?
AIDS is a particular problem in Africa for reasons including:

• the lack of information and education about AIDS
• poverty
• cultural issues to do with sexuality
• poor communication
• taboos
• lack of money for treatment
• lack of social welfare

AIDS has had a major impact on Africa because so many people have become infected in the productive years of their lives.

As in many other developing regions, heterosexual transmission is the dominant mode of spread, and mother-to-child transmission is much more common in Africa than it is in industrial countries. AIDS currently kills more people in Africa per day than floods, wars and famines together. Contaminated blood products and equipment are a risk, especially for pregnant women and children suffering from anaemia as a result of malaria. Homosexual transmission is rare in Africa.

What are the patterns of transmission elsewhere in the world?
Homosexual transmission is much more common in South East Asia and Central and South America than it is in Africa. Infection from contaminated blood remains a problem in developing countries the world over, especially in sub-Saharan Africa and South Asia, as does transmission through use of unsterilised medical equipment. Injecting drugs contributes to the spread of infection in Central and South America.

What's the current picture in the UK?
In the year 2000, more people in the UK were diagnosed with HIV than in any other year since 1985, with a 7 per cent rise on the previous year. For the second year running, more new infections were acquired through heterosexual sex than through homosexual sex (1315 compared to 1096). There was also an increase in sexually transmitted infections, such as gonorrhoea, suggesting that people are putting themselves at risk by not using condoms. Health professionals and others are concerned that people are becoming complacent about the dangers.