HIV INFECTION - AIDS

What is HIV Infection ?

Human immunodeficiency virus (HIV) is a virus which infects certain cells in the body, called CD4 cells. These CD4 cells belong to the lymphocyte family of cells. They are part of the body’s immune system, which defends it against germs. The CD4 cells normally circulate in the blood, and are also found in various organs of the body. As a result of HIV infection, the CD4 cells decrease in number, and whatever cells are there, are unable to function properly. Because of this, the body is susceptible to germs, which under normal circumstances would not cause disease.

For example, a germ called Pneumocystis carinii is normally eradicated from the body by an effective immune system. If the CD4 cells are not working properly, this germ causes a type of pneumonia called PCP (Pneumocystis carinii pneumonia). This infection is quite often seen following HIV infection.

AIDS stands for Acquired Immune Deficiency Syndrome, the group of medical conditions which result from HIV infection. There are several AIDS-related infections of which PCP is the commonest. Some tumours are also likely to develop when the immune system has been affected: it is the immune system which in part determines whether tumours are « allowed » to grow in the body. The commonest AIDS-related tumour is called Kaposi’s sarcoma, which involves the skin. People who develop AIDS-related infections or tumours may remain quite well for several years.

How does HIV Infection occur ?

In people already infected by HIV, the infected cells are present in the blood, semen and secretions from the cervix (neck of the womb). These cells can be passed on to others either through sexual intercourse or via the blood. Infected cells are also found in tears and saliva but infection cannot be transmitted through these body fluids. Once transmitted, HIV gets into the CD4 cells belonging to the other (contact) person. There is then a rapid spread of infection to other CD4 cells, until the immune system regains control. A so-called latent period follows, the length of which varies from person to person. During this period, an infected person usually remains in good health. However, they can still pass the infection on to others during this time.

Why does HIV Infection occur ?

HIV infection is caught through sexual intercourse or via the bloodstream. Certain sexual practices such as penetrative anal intercourse carry a particularly high risk. This may be partly why HIV infection is more common amongst homosexual men. However, everybody who is having penetrative sexual intercourse is at risk. HIV infection is more common in certain parts of the world, such as some countries in Africa, Asia and South America, and some cities in the United States of America.

It is also possible to catch HIV infection through a needle that has HIV-infected blood on it. HIV infection is therefore more common amongst intravenous drug users who share needles. In some European cities, over half the drug users are HIV infected. Penetrative sexual intercourse with someone who belongs to one of the above groups increases your chances of catching HIV infection. Wearing a condom protects against sexual transmission of HIV infection and is strongly recommended for all casual partners. Before HIV had been identified, it was not possible to screen blood for HIV infection. As a result, some people caught HIV infection through a blood transfusion. Haemophiliacs need blood products regularly and many of them became HIV positive through their treatment.

Treatment Involved for HIV Infection

The only way to find out if you are HIV positive is to have a blood test. This can be done via your GP or at a department of genito-urinary medicine (GUM clinic, STD clinic). You may visit the clinic without a letter. The address of your local clinic can be found in the telephone book. It is usual to have counselling before having a test so that you fully understand the implications. The test actually looks for antibodies to HIV. These are proteins which the body makes gradually in response to an HIV infection. Therefore the test may be negative for as long as 6 months after you have caught the infection. If you are HIV positive, then regular monitoring of your condition is recommended.

This may include a general physical examination, looking especially at the skin and mouth. In addition, blood tests are usually taken to measure a variety of things, including the number of CD4 cells, and the level of virus in the blood. These check-ups are done 3 to 6 monthly. Further investigations may be done if particular symptoms develop. For example, with breathlessness, the doctor may do a chest x-ray. The results of recent studies of patients with low CD4 counts (less than 350) show that early treatment with more than one drug is beneficial.

There are now nearly 20 drugs available to combat HIV. The choice of drugs is complicated and specialist help is needed. Over a period of time HIV can mutate (change) and so become resistant to the drugs used. This is probably more likely in people who do not take their drugs regularly. Drugs are also used for specific AIDS-related infections: for example, Septrin is available for treating PCP. These drugs can also be given to prevent a specific AIDS-related infection happening or coming back. This is know as prophylaxis. After recovering from the specific infection, patients are usually well enough to resume their previous lifestyle. People with HIV infectioncan still become terminally ill, but drugs delay this for many years. Unfortunately, not everyone can tolerate the drugs which need to be used.

During Treatment for HIV Infection

All of the drugs have side-effects, and the severity of this varies from person to person. A thorough discussion with your specialist is needed when starting and changing treatment. The level of virus (viral load) and CD4 cells will be monitored during treatment. If the virus is detectable, then blood may be taken to check the virus’ resistance to drugs, and to measure the actual level of drug within your blood.

If HIV Infection is Left Untreated

This question must be considered in two parts. Firstly: treatment for HIV infection. Trials have shown that people who have HIV infection are likely to live longer if they are treated with three drugs instead of two. The best time to start treatment is still not known, and it is hoped that future studies will answer this important question.

Secondly: treatment for HIV-related infections such as PCP. Some of the HIV-related infections, such as PCP, can be fatal. Failure to diagnose and treat these conditions may lead to death within weeks. It is also possible to take preventative treatment for these conditions, such as Septrin for PCP, and this reduces the chance of infection coming back.

Effects on Family of HIV Infection

Your sexual partner(s) should be told that you are infected, so that they can also be tested. This can be very difficult to do and there are specially trained counsellors to help you with this problem. They can be contacted via a department of genito-urinary medicine (GUM or STD clinic). It is essential that you do not put your regular sexual partner at further risk of catching HIV infection. This means using condoms for penetrative sexual intercourse.

Women may first discover that they are HIV positive when they are pregnant. It is possible to dramatically reduce the risk of transmission to a baby with treatment. It is very important to be tested for HIV during pregnancy, so that this treatment can be made available. An experienced counsellor should be available through the antenatal clinic. Using a condom during penetrative sexual intercourse protects you from HIV infection. You should always use a condom with casual partners.