HIV is a virus which can cause AIDS. HIV stands for Human Immunodeficiency Virus, so called because it attacks the immune system, the body’s defence against disease and infection.
AIDS stands for Acquired Immune Deficiency Syndrome. A person is said to have AIDS when the body’s immune system has become so weak that it can no longer fight off a range of diseases with which, under normal circumstances, it would be able to cope. These are termed opportunistic infections.
What is a virus?
A virus is a tiny organism which enters the body’s cells and uses them to make copies of itself. When the new copies of the virus break out of the host cell, they damage and usually destroy it.
The common cold, flu and warts are all caused by viruses, which, unlike bacteria – responsible for cholera and tetanus, for example – cannot be killed by antibiotics.
HIV is far more delicate than the cold viruses, which can be passed through the air when somebody sneezes. HIV can only survive in body fluids, especially blood and semen, and can only be passed from one person to another when the infected body fluids from one enter the other’s bloodstream.
How does HIV attack?
HIV attacks the white blood cells called T cells or CD4 cells, which coordinate the body’s immune system. Once inside, the virus integrates with the T cell’s genome and a cell which should normally fight infection becomes instead an HIV factory. The new viruses weaken and destroy the cell when they break out from it.
You will probably have heard that HIV is a retrovirus. What this means is that it consists of RNA molecules which transcribe into DNA molecules in order to integrate with the T cell. (It used to be thought that RNA was only produced by DNA – not vice versa.)
The practical consequence of this is that the virus mutates very quickly, since the ‘reverse transcription’ from RNA to DNA is unstable. This means the virus quickly grows resistant to the body’s natural antibodies and is why it can become resistant to anti-viral drugs. It is one of the main reasons why a vaccine has not yet been developed. It is also a reason why you should still practise safer sex even if you are HIV+ and having sex with another HIV+ person.
Why is there no cure for HIV?
Once you are infected with HIV, you are said to be and will (as yet) always be HIV+. This is because, even if drugs or the body’s immune system destroy every infected T cell which is actively producing HIV, and the copies of the virus in the bloodstream, there will be other infected T cells in which the virus is dormant and so effectively hidden. These infected cells will become active later.
It is also because, as we’ve said above, the virus mutates and changes its appearance very quickly. It can even split into two – it is made of two RNA molecules – and recombine with other split viruses to produce a slightly different virus.
While your body will have produced antibodies to attack the last type of HIV it detected, antibodies are very specialised and won’t recognise or be able to deal with the ‘new-look’ virus. By the time new antibodies have been produced, the virus will have multiplied hugely. In other words, HIV is always a step ahead.
The other, main, reason why HIV is hard to fight is that, as we’ve said, it attacks and hides within the immune system.
Why does HIV take so long to develop into AIDS?
Even without medical treatment, it can take years from the initial infection with HIV for a person to develop AIDS. This is because the immune system does fight back and is only very gradually worn down to the point where it is hopelessly weakened. One consequence of this is that there is a very large window of opportunity for the virus to spread between people.
It should be added that new variants of HIV have been observed which progress from initial diagnosis to death in a very short period – of around six months – and which have proven drug-resistant.
How is HIV transmitted?
HIV is transmitted through ‘bodily fluids’, mainly blood and semen. Tiny traces of the virus have been found in tears and saliva, but there is no known case of this having been a means of transmission. HIV is not found in vomit, sweat or urine.
HIV can be spread when intravenous drug users share needles. The most common way it is spread is through sex.
Both vaginal and anal sex can lead to HIV being transmitted from one person to another. Anal sex is most risky, because the lining of the rectum is easily torn and the rectum is designed to absorb fluid. There is also a high concentration of white blood cells here, which the HIV targets.
You can contract HIV whether you are the active or recipient partner when having sex. If you are the active, penetrating partner, the virus can pass through tiny cuts or abrasions on your penis or through the urethra (through which urine and semen pass).
The virus can be transmitted even if one partner does not ejaculate in the other – since it is present in pre-cum.
Using lots of additional sexual lubricant may also lower the risk, but the risk remains highly significant.
HIV and oral sex
The risk of contracting HIV from giving oral sex is lower – and lower still if your partner doesn’t ejaculate in your mouth. Your saliva will help to inhibit infection – and if you swallow your stomach acids will destroy it.
However, there is a risk. It may be that your mouth has cuts or ulcers, that you have bleeding gums or that you have weakened the lining of your mouth by chewing on it. It is particularly advisable not to brush your teeth before giving oral sex.
There is almost certainly no risk from receiving oral sex.
HIV prevention
If you are having sex outside of an absolutely trustworthy, one-on-one relationship in which you have both been tested, the best way to reduce the risk of HIV transmission is to use a condom.
Quite simply, this prevents one person’s blood, semen and other bodily fluids coming into contact with the other’s blood.
This is not absolutely safe sex. It is certainly safer sex.
The main risk is that the condom will break. To help avoid this:
- Use additional lubrication to reduce the level of the friction on the condom.
- Never use two condoms – this will increase the risk of their both breaking.
- Check to see that the condom remains intact.
- Check the sell-by-date on the condom wrapper.
- Never bring the condom into contact with oil, which will degrade the latex. Only use water or silicone based lubricant.
If a condom does break and you fear you may have been exposed to HIV, you should seek post-exposure prophylactic treatment. See your GP or go to hospital as soon as possible, certainly within 72 hours.
Testing for HIV
The HIV test is for the presence of antibodies in the bloodstream. (It is possible to test for the virus direct, but this is far more complicated and time-consuming.)
There are two tests – your blood sample may be split into two – each of which is 98% reliable.
It may be that you only have one of these tests, in which a sample of blood is taken and the result returned within twenty minutes. If you test negative with this, then that negative is reliable. If you test positive, there is a 2% chance that this is a ‘false positive’. Further tests will be taken to make sure.
The test will detect HIV antibodies if it has been more than three months since you have been infected. If you have been infected within the last three months, then the test won’t work.
Where should you go to be tested?
It is recommended that you go to a sexual health clinic or HIV testing centre to be tested. This is for reasons of confidentiality. A sexual health clinic will never reveal your result to anyone – and need not even know who you are.
If you test via your GP, it may be that insurance companies will ask you if you have ever had an HIV test and will request your permission to contact your GP. There may be problems if you refuse this request.
Should you be tested for HIV?
If you are at all concerned that you might have been exposed to HIV, it really is best to be tested.
At best, you’ll be free of the worry.
If the result is positive, you will know that you will have to be regularly monitored and can begin treatment when necessary.
Going for a test can be scary – indeed terrifying. You should think very carefully beforehand about how you will respond if the result is positive. The doctor will try to assure himself before testing that you are not going to harm yourself if you test positive. Counseling will also be offered afterwards.
If I test negative, does that mean I’m immune?
No. It means you’re lucky. It is as yet impossible to become immune to HIV.
Early symptoms of HIV infection
The first symptoms of HIV infection can occur when a person is first infected with the virus. There may be a cold- or flu-like illness, called a sero-conversion illness. This is the body’s response to the HIV infection, as the immune symptom attempts to destroy the virus.
It is highly likely that people will ignore the symptoms. They’ll run a fever and feel rundown and tired with aching muscles. Their lymph glands might also become swollen. They’ll think they have the flu or a cold.
The symptoms will then pass and the person will feel healthy again. This is the stage known as asymptomatic HIV infection, or category A HIV.
They may remain well for years – though this does not mean that they will not catch the usual illnesses anyone is susceptible to. It is only when an HIV+ person contracts an illness which is a result of HIV that he or she is said to have progressed to symptomatic, or category B, HIV infection.
Opportunistic illnesses
The most common AIDS-defining illnesses, which take advantage of the failure of the immune system, are:
- Pneumonia. This was the main cause of death from AIDS in the 1990s in Britain.
- Kaposi’s sarcoma. This is a type of cancer which mainly affects the skin and can also affect the gut, the lungs and the lymph nodes. This was the main cause of death in the 1980s.
- Cytomegalovirus. This damages the retina in the eye and can cause weight loss, fever, ulcers and diarrhea.
- Tuberculosis. This damages the lungs and the brain.
- Mycobacterium avium intracellulare (MAI). This causes night sweats, severe anaemia, chronic diarrhea, loss of appetite and weight loss.
Treatment for HIV
A range of drugs is available which interferes with the way HIV reproduces itself, slowing down the spread of the virus and giving the body a chance to catch up.
The different drugs interfere with different stages of the virus’s reproduction cycle. A combination of drugs is taken, which is why the treatment is called combination therapy.
HIV+ people will not automatically be given the anti-retroviral drugs (so called because HIV is a retrovirus). What will happen is that doctors will monitor the number of T cells, or CD4 cells, in the blood, waiting for the time when this number falls below a critical level. Your viral load, the amount of active HIV in your body, will also be monitored.
The CD4 count is a measure of the number of CD4 cells in every microlitre of blood. A healthy and HIV- person will usually have a CD4 count of over 500.
The CD4 count falls as the HIV weakens and destroys the immune system.
When the CD4 count falls below around 350, and certainly as it approaches 200, a person will be given therapy.
The aim of treatment for HIV is to bring the viral load down to zero – though there will still be inactive HIV in the body – and to give the immune system, or the CD4 count, a chance to recover.
What are the side-effects of HIV treatment?
Combination therapy can result in a variety of side-effects, including headaches, nausea, dizziness and diarrhea. The side-effects may fade – and it is also possible to experiment with different combinations of drugs to find that which works best for the individual.
In the long term, other side-effects might emerge, including:
- Liver damage.
- Neuropathy – or damage to the nerves in the feet and hands.
- Anaemia – a deficiency of red blood cells, this leading to tiredness and weakness.
- Lipodystrophy. This is a wasting and redistribution of body fat. Symptoms include wasting of the face, the arms, the buttocks and legs, a swollen stomach and a hump of extra fat at the back of the neck.
Drug resistance
HIV can develop resistance to the anti-retroviral drugs. When this happens with regard to a particular drug, that drug will stop working.
This is a recognised problem. At the moment, it is possible to change the combination of drugs when resistance develops, introducing new drugs against which the virus in any one person’s body is not immune.