What causes AIDS is the HIV virus.
AIDS isn’t actually a disease in the true sense of the word. The term stands for acquired immune deficiency syndrome and is basically a “catch all” expression used to describe a range of illnesses brought on by an immune system weakened by HIV (Human Immunodeficiency Virus).
In a nutshell AIDS is the end stage of a relentless virus which begins with no symptoms and gradually progresses to a stage of severe symptoms with a destroyed immune system and a body just crying out for infections and cancers.
To understand what causes AIDS, it’s important to understand HIV - see What is HIV?
HIV damages a person’s ability to fight infections and disease. When it enters the body through bodily fluids - i.e. semen, blood, breast milk or vaginal secretions - it goes looking for infection fighting white blood cells known as T-cells, more commonly termed CD4+ cells.
The virus launches itself at the CD4+ cells causing them to die while at the same time releasing billions of copies of HIV back into the blood stream. These then go looking for new cells and so the lethal cycle continues.
For up to 10 years a person may be symptom free as the body produces enough CD4+ cells to cope with the virus. But the virus begins to take over the body, the immune system starts to die off and infections creep in.
There comes a time when the body can no longer cope with the number of infections being thrown at it and despite some extraordinary medical advances aimed at controlling the virus in recent years, full blown AIDS takes over. Generally speaking this means that the immune system of the HIV infected person has been so badly damaged that they have acquired a life threatening illness which would not normally be a problem for someone with a healthy immune system. These illnesses include infections such as pneumonia or tuberculosis.
The point at which a person is declared to have AIDS varies from one country to another. In many western countries a CD4+ count of less than 200 shows that a person has a very badly damaged immune system and now has AIDS. Even if the count goes above 200 at a later date, that person is still regarded as having AIDS.
There has been some speculation that HIV is not the cause of AIDS. Some researchers, although they are very much in the minority, believe that the collection of diseases known as AIDS could be down to an unknown virus attacking an immune system which for some reason is generally weak.
This theory has been rubbished by most scientists. The one common factor among AIDS patients - whether they are gay, heterosexual, haemophiliacs or drug users - is that they carry the HIV virus.
Unfortunately there still isn’t a cure for HIV and therefore nothing to prevent the final onset of AIDS in many cases.