OBJECTIVES When you have completed this unit you should be able to: Understand the meaning of HIV infection and AIDS. Describe the different ways that HIV can be transmitted. List the three phases of HIV infection. List the common presentations of AIDS in adults. Describe how HIV infection is diagnosed. List the factors which influence the risk of becoming infected with HIV. Describe how HIV damages the immune system. List the groups of drugs used to treat HIV infection. Prevent HIV infection of staff by needle stick injuries.

COPYRIGHT

All rights reserved. No part of this Perinatal Education Programme may be altered in any way without the written permission of the editorial board of the Perinatal Education Trust. To facilitate the improvement of perinatal care, the Programme may be reproduced for teaching purposes provided due acknowledgement is given and the material is not sold for financial profit. While the advice and information in the Programme is believed to be accurate, the editorial board cannot accept responsibility or liability for any errors or omissions that may have been made.

ISBN 0 7992 1955-X

31-1 WHAT IS HIV?

HIV is a virus and the letters HIV stand for the Human Immunodeficiency Virus. HIV infects people for life and causes a chronic illness called AIDS. It infects mainly the immune system, particularly lymphocytes, but may also infect other organs such as the central nervous system and intestines. HIV infection can be spread from one person to another.

HIV infection is a new condition and the virus was first identified in Paris in 1983. Since then it has spread to almost every country in the world and by 2004 over 50 million people world-wide had HIV infection. South Africa has one of the fastest growing HIV epidemics in the world with one to two thousand people infected every day.

*** Two types of HIV are recognized, HIV1 and HIV2. Most infection in Southern Africa is caused by HIV1 which has many subtypes (clades). The important subtype in Africa is subtype C while subtype B is the most common subtype in the developed world.

HIV is probably a new human virus which first appeared in the 1950s. It was possibly first transmitted to humans from monkeys in central Africa. From here it rapidly spread to all parts of the world, especially the USA, Europe, Asia and other parts of Africa.

31-2 WHAT IS A VIRUS?

Viruses are extremely small, very simple organisms which can only exist and multiply by invading and taking control of a plant or animal cell (the host cell). Viruses are responsible for many diseases. Unlike bacteria they are not killed by antibiotics. Viruses may be divided into many different groups. HIV belongs to a group of viruses known as retroviruses.

31-3 WHAT ARE RETROVIRUSES?

They are a group of viruses which are unique in nature as they have an enzyme called reverse transcriptase. This special enzyme enables HIV to introduce its own genes into the nucleus of the host cell. The host cell is then instructed to produce many millions of new HIV. These HIV are released into the blood stream and can then infect other cells. Retroviruses usually cause long periods of silent infection before signs of disease appear. *** Retrovirus contain a RNA genetic code. The enzyme reverse transcriptase allows HIV to make DNA copies of (transcribe) its RNA. The DNA copy is then inserted into the DNA of the nucleus in the host cell. This enables the virus to take over control of the host cell and instruct the host cell to produce huge numbers of new HIV. Only retroviruses have this ability to make a DNA copy of their RNA code. Retroviruses are common and some cause cancers in animals.

HIV IS A RETROVIRUS

31-4 WHAT IS AIDS?

AIDS stands for the Acquired Immunodeficiency Syndrome. This is a clinical illness which may present in many different ways. It is a slow, progressive and permanent disease. AIDS was first recognized among homosexual males in the USA in 1981. The next year it was diagnosed in heterosexual men and women in Africa.

AIDS IS A CHRONIC, FATAL DISEASE CAUSING A WIDESPREAD EPIDEMIC IN AFRICA

Most cases of AIDS occur in Africa. The spread of the AIDS epidemic is greatest in Southern Africa. In 2004 it is estimated that 5.3 million adults and children have HIV infection in South Africa alone.

MORE THAN 5 MILLION SOUTH AFRICANS ARE INFECTED WITH HIV

31-5 CAN YOU HAVE HIV INFECTION AND NOT AIDS?

Yes. A person is usually infected with HIV for years before becoming ill with the clinical signs of AIDS. Therefore, most people infected with HIV are clinically well for many years.

31-6 HOW CAN YOU BECOME INFECTED WITH HIV?

The virus may be transmitted from one person to another by:

1. Unprotected heterosexual or homosexual intercourse (horizontal transmission).
2. Crossing from a mother to her fetus or newborn infant (vertical transmission).
3. Using syringes, needles or blades, which are soiled with HIV infected blood, and shared by intravenous drug abusers or not correctly cleaned and reused by health workers.
4. Accidental needle stick injuries in health care workers.
5. A blood transfusion with HIV infected blood or other HIV infected blood products such as factor VIII in haemophiliacs. This is very rare as all blood products are screened for HIV.

There is no evidence that HIV can be spread by mosquitoes, lice or bed bugs. In Africa HIV is most commonly spread by heterosexual intercourse.

HIV IS USUALLY SPREAD BY SEXUAL INTERCOURSE

31-7 CAN AN HIV INFECTED PERSON WHO IS WELL TRANSMIT THE VIRUS?

Yes. HIV is frequently transmitted by people who appear to be clinically well but are infected with HIV. This is the great danger of HIV infection as most infected people do not know that they have been infected. They are also unaware that they may transmit HIV to another person.

31-8 HOW MAY YOU BECOME INFECTED DURING SEXUAL INTERCOURSE?

By contact with infected body fluids which contain large amounts of HIV:

1. Vaginal and cervical secretions.
2. Semen.
3. Blood.

The spread of HIV between adults by sexual intercourse is called horizontal transmission.

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