What is HIV?
HIV stands for “human immunodeficiency virus”. It is a retrovirus. This means that the virus uses the body’s own cells to reproduce itself. While several theories exist, the origin of this virus is still unclear.
How does the virus affect the body?
The immune system of a healthy individual is able to fight infections from invading bacteria, viruses and diseases to which the body is exposed.
HIV attacks the immune system, thereby weakening it and making it vulnerable to infections.
How does the virus work?
The immune system consists of T-helper cells that contain a protein called CD4.
The virus enters the blood and gains access to the T-helper cells by attaching itself to the CD4. Once inside, the viral genetic material called RNA (ribonucleic acid) changes into viral DNA (deoxyribonucleic acid) by an enzyme called reverse transcriptase. The viral DNA becomes part of the human DNA, which, instead of producing more cells of its own type, starts producing HI viruses.
An enzyme called protease organises the viral chemicals and a new virus is formed. This virus then exits the cell, killing it in the process, and floats freely in the bloodstream, ready to infect another cell.
The body responds to this invasion by creating more T-helper cells, thereby creating more cells for the virus to infect.
The process takes time. Eventually, the immune system is too weak to fight infections to which the body is exposed.
The normal range for CD4+T cells in a healthy person is 800 to 1 200 cells per cubic millilitre of blood. When an HIV-infected person’s CD4+ T cell count falls below 200, he or she becomes increasingly vulnerable to opportunistic infections.
How is the virus transmitted?
HIV is commonly spread through body fluids such as blood, semen, vaginal fluid, breast milk and other fluids containing blood.
The virus is transmitted through the following ways: by having unprotected sex with an infected person; through infected blood; by sharing needles with an infected person; and through blood transfusions (where the blood has not been screened for the virus). Pregnant women can also pass the virus to their babies during pregnancy or delivery as well as through breast-feeding.
What is Aids?
Aids stands for “acquired immune deficiency syndrome”. A syndrome is a collection of symptoms and illnesses.
When a person is infected with the virus, he or she is said to be HIV-positive. This means that the person is carrying the HI virus and the process of immune-system deterioration has begun.
HIV/Aids usually has a long incubation period. This means that a person may be infected for many years without showing any symptoms.
HIV infection can, theoretically, be divided into four stages or phases:
- The primary HIV-infection phase (or acute sero-conversion illness): This phase is characterised by infection of the virus or sero-conversion. Sero-conversion usually occurs four to eight weeks after infection with the HI virus. Some people experience flu-like symptoms such as a sore throat, headache, mild fever, fatigue, muscle and joint pains, swelling of the lymph nodes, a rash and (occasionally) oral ulcers. These symptoms usually last for between one and two weeks.
- The asymptomatic latent phase: In this phase, the person does not experience any symptoms, but the virus remains active. Infected people are usually not aware that they have the virus and may unwittingly infect others.
- The symptomatic stage: In this phase, the person begins to experience symptoms. At first, they appear to be mild, such as mild to moderate swelling of the lymph nodes in the neck, armpits and groin; occasional fevers; skin rashes and nail infections; weight loss up to 10% of the person’s usual body weight; general feelings of tiredness and not feeling well.
Later, major symptoms and appear as the immune system deteriorates. At this stage, the CD4 count is very low while the viral load is high. Opportunistic infections appear, as well as oral and vaginal thrush infections that are very persistent and recurrent (candida); recurrent herpes infections such as cold sores (herpes simplex); recurrent herpes zoster (or shingles); night sweats; persistent diarrhoea for more than a month, and weight loss (more than 10% of the usual body weight)
Aids-defining conditions
It usually takes about 18 months for the symptomatic stage to develop into full-blown Aids. At this stage the immune system is too weak to fight disease and opportunistic infections. Symptoms become more acute and the person becomes infected by rare and unusual organisms that do not usually respond to antibiotics.
Persons in the final stage of Aids typically have a very short time to live. They may be plagued by the following problems: respiratory infections, persistent cough, chest pain and fever; pneumonia, especially pneumocystis carinii pneumonia (PCP); severe herpes zoster (shingles); Karposi’s sarcoma; lymphoma or cancer of the lymph nodes; and tuberculosis, which is a very serious opportunistic infection that affects people with Aids. According to a United Nations Joint programme on HIV/Aids report in 2000, up to 50% of HIV-infected individuals in Africa have active tuberculosis.
How is HIV/Aids treated?
Although there is no cure for HIV/Aids, the disease can be managed by living a healthy lifestyle and using anti-HIV drugs. An HIV-positive person may live with the disease for a long time.
The primary method of treating HIV/Aids is the use of drugs called antiretrovirals (ARVs). These are potent drugs that slow down the growth of the HI virus in the body by inhibiting the two enzymes responsible for replication, reverse transcriptase and protease.
Experts recommend taking a cocktail of three or more ARVs known as combination therapy or highly active ARV therapy. Using monotherapy (one drug only) may have short-term effects, but the virus quickly becomes resistant to it.
How does ARV therapy work?
As mentioned earlier, the HI virus enters the T-helper cell by attaching itself to the CD4 protein. Once inside, the reverse transcriptase enzyme changes the viral RNA into viral DNA that joins the human DNA. The cells now produce viral RNA that assembles and buds out of the host cell to form a new virus.
ARV drugs are classed into three main groups:
1. Nucleoside analogue reverse transcriptase inhibitors (NRTIs). These drugs target the HIV protein reverse transcriptase, preventing the translation of viral RNA into viral DNA (such as AZT, ddl, ddC and 3TC).
2. Non-nucleoside reverse transcriptase inhibitors (NNRTIs). These also target the reverse transcriptase but in a slightly different way (such as nevirapine, delavirdine and efavirenz).
3. Protease inhibitors (PIs). These target the HIV protein protease and block it so that a new virus cannot assemble in the host cell and be released.
By slowing down the reproduction of HIV, these drugs help give the body a chance to build up its CD4 count and thereby boost the immune system.
Because the HI virus replicates so rapidly, sometimes “mistakes” are made in the process. These are called mutations. This means that the original virus may not be the same as the reproduced one.
Because the ARV drugs target certain strains of HIV, other strains, like the mutated ones, will not be affected by these drugs and they become drug resistant. They are also able to produce more strains that are unaffected by drugs. It is therefore vital that the drugs be taken exactly as prescribed.
Preventative measures can be taken to ensure that one is not infected with HIV, such as safer sex (using a condom during sexual intercourse), abstinence and being faithful to one partner.
Research is currently being conducted by, among others, the South African Aids Vaccine Initiative into the developing of a vaccine for general use.
Are there side effects to the drugs?
As with any drug, ARV drugs do cause certain side effects. Different people experience different effects and the degree to which it is tolerated or accepted varies from person to person.
Possible side effects include: headaches; fever; fatigue; diarrhoea; vomiting; nausea; loss of appetite; abdominal pain; skin rashes; lactic acidocis; pancreatitis; anaemia (decrease in red blood cells); and hepatitis (inflammation of the liver).
In general it is always best to be well informed and to consult a doctor when taking these drugs.
How do I get tested for HIV?
The HIV antibody test is available free of charge at certain clinics and GPs.
After infection, it may take up to three months for the HIV antibodies to be produced. So, if a person is concerned that he or she may be infected, he or she may only know after the three-month “window period”.
A person should receive pre- and post-test counselling in which the testing procedure and the possible results are explained.
The most commonly used test is called the Elisa (enzyme-linked immunosorbent assay) test. It tests for the presence of antibodies (the immune system’s response) to the HI virus.
PCR (polymerase chain reaction) tests for the presence of the virus itself, and can therefore be used from two weeks after infection. This test costs approximately R350.
Rapid HIV tests look for antibodies to the virus, but do not require specialised laboratory equipment. This makes them both cheaper and quicker than the Elisa test.
What is MTCT (mother-to-child transmission)?
A pregnant mother can pass the HI virus to her unborn child. This is known as mother-to-child transmission or vertical transmission. MTCT is one of the major causes of HIV infection in children.
The virus is transmitted in three ways: via the placenta during pregnancy, through blood contamination during childbirth or through breastfeeding.
The virus cannot be transferred directly from an infected father to the baby. The mother first has to be infected for it to transfer to the baby.
Should HIV-positive mothers breastfeed?
There is an ongoing debate about whether HIV-positive mothers should breastfeed their babies.
In Africa, there are very complex factors to take into consideration, such as:
- mothers may not have access to clean and safe water supplies;
- formula milk may not be accessible and is often too expensive;
- mothers may not know how to prepare the formula safely; and
- mothers are often stigmatised for bottle-feeding
In these cases, the World Health Organisation recommends breastfeeding to prevent the baby dying from malnutrition or diarrhoea.
Can MTCT be treated?
ARVs such as AZT and nevirapine can substantially reduce the chances of MTCT but is not a cure for the mother.
The South African government has started to implement a comprehensive programme for the prevention and treatment of MTCT.
What about Aids in South Africa?
The first recorded case of HIV in South Africa was in 1982. South Africa is currently one of the most severely affected countries in the world. It is therefore essential to monitor the growth of this epidemic effectively.
The national HIV prevalence was first calculated in the 1990s using an antenatal survey. This is a mechanism developed by the Department of Health to monitor and research the growth of the epidemic. It involves a series of annual HIV surveys among women attending antenatal clinics in the public health sector. The survey uses pregnant women to gain estimates of HIV prevalence.
According to the 2001 antenatal survey, it was estimated that 4,74-million people had been infected in South Africa.
This type of survey does, however, have some limitations. For example, estimating national prevalence in the general population is difficult since the survey is limited to pregnant women.
It is also difficult to draw conclusions about parts of the population that are not sexually active or those who have adopted prevention practices such as condom use.
This presents a need for surveillance tool with a deeper understanding of the epidemic and that includes behavioural patterns.
In December 2002, the first independent and nationally representative study of HIV/Aids was released.
The study — commissioned by the Nelson Mandela Foundation and the Nelson Mandela Children’s Fund and conducted by the Human Sciences Research Council in collaboration with the Medical Research Council and the Centre for Aids Development, Research and Evaluation — sampled 9 963 people countrywide and included anonymous saliva-based HIV tests from 8 840 participants.
The study presented a national prevalence of 11,4%. This means that 4,5-million people were infected.
What is the government’s response to Aids?
The South African government and civil society have been at odds about the provision of ARV drugs to the public, in particular to mothers infected with HIV to prevent transmission to their unborn children.
This tension has been worsened by the debate about the causal link between HIV and Aids and our president’s involvement with known dissidents in the scientific community.
However, in a statement released in April 2002, the government stated its commitment to intensifying its campaign to prevent HIV infection. It was also stated that this campaign rests on the premise that HIV causes Aids.
The government’s response included the development of the HIV/Aids and STI Strategic Plan for South Africa, 2000-2005.
This is a broad national strategic plan that includes the following priority areas:
Prevention
- Promoting public awareness and a safe and healthy lifestyle
- The effective management of sexually transmitted diseases
- Reducing mother-to-child transmission
- Providing adequate access to voluntary testing and counselling
- Providing post-exposure services
Treatment, care and support
- To provide adequate treatment, care and support in health facilities and communities
- Work to lower the cost of ARVs and make them accessible
- Improving the programme of home-based care
- Research, monitoring and surveillance
- Development of a vaccine
- Conduct regular surveillance of the epidemic
Human and legal rights
- Developing an adequate legal framework that ensures an appropriate social environment
- The problem of making ARVs accessible to the public is further complicated by patent protection
The World Trade Organisation’s (WTO) agreement on Trade-Related Aspects of Intellectual Property Rights (Trips) obliges all WTO member states to provide 20 years of patent protection for medicines. This means that the production of generic drugs is prohibited during this period.
This agreement may only be overridden in a case of national emergency or in circumstances of extreme emergency. Trips allows for the issuing of compulsory and voluntary licensing.
Voluntary licensing means that the government grants a production licence to a third company to produce the generic drug with the consent of the patent holder. The patent holder usually receives a token royalty.
With compulsory licensing, the production licence is granted without the consent of the patent holder.
The South African Patents Act provides for compulsory licensing in the event that the patent holder can be shown to abuse the patent.
In February 1998, a court action was instituted against the South African government by the Pharmaceutical Manufacturers’ Association (PMA) to defend the industry’s patent rights.
The action was aimed specifically at section 15c of the Medicines and Related Substances Control Amendment Act, which allows the government to purchase drugs from other countries where prices are lower, therefore allowing for parallel trading of those drugs with the local equivalent as well as compulsory licensing.
The case was withdrawn in April 2001 due to international political and public pressure.
In 2001, the Treatment Action Campaign (TAC) launched a legal appeal against the government to provide the ARV nevirapine to pregnant HIV-positive mothers to prevent mother-to-child transmission.
In December 2001, the Pretoria High Court ruled in favour of the TAC and ordered the state to make nevirapine available to women at public facilities that were not part of the existing pilot sites.
The government lodged an appeal with the Constitutional Court stating that the judiciary could not issue orders concerning matters of government policy.
The appeal was granted by the Pretoria High Court and in April 2002, the Constitutional Court issued an interim order that obliged the government to provide nevirapine in public facilities that had the capacity to administer it. This was followed by a ruling in favour of the TAC.
In a Cabinet statement released in April 2002, the government announced that it was intensifying the campaign against HIV/Aids and its prevention.
What is post-exposure prophylaxis?
Prophylaxis refers to disease prevention. Post-exposure prophylaxis (PEP) means taking ARVs directly after one has been exposed to HIV to stop the exposure leading to infection.
PEP may be given in cases of needle-stick injuries. This refers to health workers who accidentally prick themselves with needles containing contaminated blood.
PEP may also be administered in the case of sexual assault.
Currently the national protocol for administering prophylactic ARVs have been modelled on those administered for needle-stick injuries. It is offered after survivors have been given comprehensive counselling as part of the existing service to rape survivors.
Definitions
- Sero-conversion refers to the moment the person’s HIV status changes from negative to positive.
- Viral load refers to the amount of free virus particles detected per millilitre of blood.
- Opportunistic infections are infections that lead to disease in people with a weakened immune system.
- National HIV prevalence refers to the number of current cases per population at risk.
- Generic drugs are cheaper versions of the same drug.
Source: Health-e