|
|
|
|
|
|
|
Understanding HIV and AIDS
What is HIV and AIDS? HIV (Human Immunodeficency Virus) is a virus which attacks the body's immune system. For a certain period of time, which may be several years, the body's defence mechanism will keep the HIV infection under control. During this time, a person with HIV may feel completely well and have no symptoms. However, in the majority of cases, the immune system eventually needs help, in the form of anti-HIV drugs, to keep the HIV infection under control.
Although you may still hear the term AIDS (Acquired Immune Deficiency Syndrome) it is no longer used by doctors. They prefer to talk of late-stage or advanced HIV infection. Before effective treatments, AIDS was a state someone infected with HIV almost inevitably entered as HIV attacked their immune system. This is no longer the case.
How is HIV transmitted? HIV and sex In order for someone to become infected, a sufficient amount of HIV must enter their bloodstream. This level of HIV is found in some, but not all of the body fluids of someone infected with HIV. Those body fluids which contain enough HIV to infect someone are:
Other body fluids like saliva, sweat or urine do not contain enough virus to infect another person. There are a number of routes, all quite difficult to achieve by accident, by which infectious body fluids from someone with HIV may enter the bloodstream of someone else:
HIV cannot pass through intact external skin. It cannot pass through the air like a cold or flu virus.
HIV and Sex HIV can pass from an infected person to an uninfected person during unprotected penetrative sexual intercourse; that is, sex where the penis, unprotected by a condom, enters the vagina or anus. Using a condom with a water-based lubricant or a femidom during vaginal or anal penetrative sex will prevent transmission of HIV and many other sexually transmitted diseases.
HIV and sexual intercourse between men Up until recently, in the UK, Northern Europe and parts of the United States, the most serious impact of the virus has been felt by gay men. Thirty four percent of men in the UK who were infected by HIV before the end of 2002 were infected through sexual intercourse with other men.
HIV and sexual intercourse between men and women The number of people becoming infected through unprotected heterosexual sex is increasing. In 2002, in the UK, 63 per cent of all people infected with HIV became infected during unprotected sex with someone of the opposite sex who had HIV.
Unlike the UK, USA and Northern Europe, in Asia and sub-Saharan Africa, HIV is transmitted most frequently by sexual intercourse between men and women. In the UK, HIV has had a devastating effect on communities of people from parts of Africa where HIV has taken hold.
HIV and oral sex It is possible for HIV to be transmitted through oral sex. As far as we know, sucking on the penis of a man with HIV is the type of oral sex most likely to lead to transmission of HIV. Although there is enough virus in semen to infect another person, it is difficult for the virus to survive in the mouth, and it is difficult for the virus to get from the mouth into the blood stream.
Licking the labia or clitoris of a woman with HIV is less risky than oral sex with a man who has HIV. Someone whose genitals are sucked or licked by a person with HIV is less likely to become infected. But a small number of cases of infection through this route are known.
HIV and other sexual activities One sexual activity which is risky if one partner has HIV, is sharing a sex toy. That is, inserting an object into the vagina or anus of more than one person without washing it carefully between users or putting a clean condom on it between users.
It is hard for HIV to be passed from one person to another through: deep kissing, mutual masturbation, or via fingers inserted into the vagina or anus, unless covered in blood or other infectious fluids.
HIV and shared injection equipment In 2002, in the UK, 2 per cent of those who became infected with HIV did so through sharing drug injecting equipment with someone with HIV. Sharing injecting equipment is as risky as having unprotected sex with someone who has HIV. In Scotland, Southern Europe and parts of the USA, shared drug injecting equipment is the most common route of infection.
People who inject drugs can avoid transmitting HIV and other viruses present in the blood, either to themselves or to others, by using new injecting equipment every time, or by sterilising equipment between users. To combat the spread of HIV and other viruses among people who inject drugs through contaminated injecting equipment, many countries have initiated needle exchange programmes. That is, making available free clean injecting equipment to people who inject drugs.
HIV and blood transfusions Early in the epidemic, a number of people in the UK were infected with HIV through blood transfusions. However, all blood donations and tissue donations in the UK have been tested for HIV since 1985. In some countries, infection through blood transfusion is still a significant risk.
Haemophilia Factor 8 is a product of donated blood which is used by people who have haemophilia. Before it was known that donated blood might contain HIV, many people with haemophilia became infected in the UK through receiving contaminated blood products. All blood products are now treated to destroy any HIV which may be present.
HIV and pregnancy A women with HIV, who becomes pregnant can sometimes transmit the virus to her baby before or during birth (vertical transmission). HIV can also be passed to a baby during breastfeeding if the mother has HIV. In the absence of any preventative interventions, the risk of vertical transmission is about one in seven.
This risk can be greatly reduced if the pregnant woman is given a short course of an anti-HIV drug, starting a few weeks before the birth and continued, to both mother and new born, for a short period after the birth. (The most effective anti-HIV drugs to be given to the mother before birth, and how long she should take them are both areas of current research activity.) The other two interventions which greatly reduce the risk of vertical transmission are: delivering the new born by elected Caesarean section and avoiding breastfeeding, as breast milk contains significant levels of HIV. If these three preventative interventions are followed, the risk of vertical transmission has been shown to fall to as low as two in 100.
In the UK in 2002, 57 children were born infected by HIV as a result of vertical transmission.
What is the HIV test? The HIV test shows whether someone has HIV, the virus that is responsible for what was in the past called AIDS. It is not a test for AIDS.
Antibodies The most commonly available HIV test is more properly called an HIV antibody test, because it looks for antibodies to HIV. Antibodies are created by the infected person's immune system in response to the presence of HIV. the window period (seroconversion) When someone becomes infected with HIV, it can take up to three months for their immune system to produce enough antibodies to show up on an HIV test. This gap is called the window period, or seroconversion. Throughout this window period, the person with HIV does, however, have enough virus in their blood and sexual fluids (and breast milk) to infect another person. Indeed, the level of virus in their body fluids (viral load) at this time can be extremely high, making them particularly infectious.
Because the HIV test looks for antibodies, taking an HIV test less than three months after infection might not give an accurate result.
A positive result If the test finds HIV antibodies, the result is said to be positive. You would then be HIV antibody positive or 'HIV positive'. This means you have HIV infection. It does not mean you have AIDS. The test cannot show whether you are ill, or are going to become ill. For those found to be HIV positive, combination therapy can successfully reduce the level of HIV in their blood and has had a dramatic effect in improving the health of many people with HIV.
A negative result If the test does not find HIV antibodies, the result is said to be negative. A negative test result shows that the person does not have HIV, as long as the test was done after the end of the window period.
An unclear result Very occasionally, the HIV test result can be unclear. It is not clearly positive or negative. In most cases this is because the test has found some random antibodies which have nothing to do with HIV. However, very rarely an unclear result can occur during the window period. This means the person taking the test has HIV but HIV antibodies are only just beginning to form. If the HIV test result is unclear, the clinic may send the blood sample away for further tests. Or you may be advised to have a repeat HIV test four to six weeks after your unclear result. In either case, this result is likely to be clearly positive or negative.
Testing for HIV itself Another blood test called an antigen test will find HIV itself, (as opposed to antibodies) if it is present. This test looks for a part of the HIV virus which is detectable in the body around two or three weeks after infection, but before HIV antibodies have had time to form. It is not used as widely as the antibody test but may be used in special circumstances.
How does HIV affect the body? After a while, HIV will begin to weaken the body's immune system, which usually fights off any infections. The major damage HIV causes to the immune system is to white blood cells known as CD4 cells, which sets the immune system in motion when organisms such as viruses, bacteria and fungi enter the body.
HIV infects CD4 cells and uses them to make new copies of HIV. These copies then go on to infect more cells. Over time, as the number of healthy CD4 cells declines, the immune system's ability to fight infections can be greatly reduced.
HIV reproduces even in someone who is feeling well. If their immune system is working well, the virus will only reproduce a little. But if their immune system is damaged through prolonged or serious illness, the virus can reproduce itself much more easily. Research shows that people with higher levels of HIV in their bodies have a greater risk of becoming ill than people with less HIV in their bodies. What are the long term effects of HIV? The CD4 cells of someone infected with HIV mount a defence against the invading HIV and it may be held at bay for many years. But the virus is not completely destroyed or eliminated from the body, and it continues to attack CD4 cells. Eventually, the number of CD4 cells declines and the amount of virus present increases.
When the number of CD4 cells starts to decline, the infected person becomes vulnerable to other infections. The organisms which cause these infections are easily kept under control by a healthy immune system. They are able to cause illness only when the immune system is severely damaged, so the illnesses they cause are known as opportunistic infections. Examples of opportunistic infections include:
Research has shown that taking a combination of anti-HIV drugs (combination therapy) can slow down the damaging effect of HIV on the immune system. When combination therapy is successful, it can improve and sustain the health of someone with HIV and will mean they are less likely to develop what were previously known as AIDS-defining conditions.
How effective is anti-HIV treatment? Current therapy can successfully reduce the level of HIV in blood and has had a dramatic effect in improving the health and life expectancy of people with HIV. However, we do not yet know the long term effects of these drugs or whether the improvement people are experiencing can be sustained indefinitely.
In the seven years that these drugs have been available, many who were seriously ill have returned to good health and in many cases returned to work. In some people, however, the virus can develop resistance and cross-resistance to the drugs (cross-resistance means that the virus becomes resistant to other drugs, which work in the same way as the actual drug used). A minority of people are unable to benefit from the current anti-HIV drugs.
How can you tell if the treatment is working? People living with HIV regularly use two tests to monitor the progress of the infection, and these are especially important for anyone beginning or using combination therapy. Both tests involve having blood samples taken.
CD4 count: A CD4 count measures the number of CD4 cells in the blood. The lower the CD4 count, the more damage the immune system has sustained from HIV infection.
Viral load: This tests the amount of HIV in the blood. The higher the viral load, the more virus there is in the blood. One of the aims of combination therapy is to drive down viral load and to keep it suppressed. If the measurement of viral load comes back as 'undetectable' this does not mean there is no HIV in the blood. It means that there are too few particles of virus to be detected by the test. There are still some there, just not very many. In addition, HIV may be undetectable in the blood, but there can still be HIV in semen, vaginal fluids and other bodily fluids. So it is advisable to continue practising safer sex even with a low viral load, as there is still a risk of HIV transmission.
Can combination therapy fail? In order for combination therapy to work, one needs to continuously maintain a certain level of the anti-HIV drugs in the blood. If this level falls, they will not work effectively and HIV will continue to reproduce. The level of drugs in the body can fall if someone regularly forgets to take them on time, misses doses, or doesn't follow dietary instructions (that is, if they don't adhere to the drug regimen).
Someone's combination therapy can also fail if HIV infection has damaged the lining of their gut, which can make it difficult for them to absorb the drugs properly.
Drug resistance Combination therapy can also fail because HIV develops resistance to one or more of the drugs in the combination. HIV can develop resistance by changing (mutating) slightly so that it can reproduce in spite of these drugs. This new virus can then multiply and continue to damage the immune system, unless the person changes to another drug combination which will work against the new strain of HIV in their body.
Such drug-resistant strains of HIV are now increasingly being transmitted. People who become infected with drug-resistant HIV will have their treatment options limited from the start of combination therapy. This emphasises the importance of practising safer sex and avoiding infection by drug-resistant strains of HIV.
Does this mean there’s now a cure for HIV? No. Despite the hype, at present these drug combinations do not completely eliminate HIV from the body, or suppress HIV to such low levels that it cannot cause longer term damage to the immune system.
What happens when someone has HIV? Most people who become infected with HIV do not notice that they have been infected. A few weeks after infection, the body's immune system reacts to the virus by producing antibodies. Some people with HIV have a short 'seroconversion' illness at the time these antibodies are created. The likely symptoms are the normal response to many other infections, and may include a sore throat, a fever or a rash.
Someone living with HIV will have their CD4 count and viral load regularly monitored by means of simple blood tests. The results of these tests vary in response to infections, stress, exercise and the time of day, but it is of primary importance in indicating how their health is holding up under the assault of HIV. When someone has lived with HIV for a long time and their immune system has been severely damaged, there is a risk of opportunistic infections. Increasingly, it is possible to prevent or treat these opportunistic infections using drugs. For example, Pneumocistis carinii pneumonia (PCP) was a frequent cause of death in people with AIDS or late stage infection in the early years of the epidemic. Doctors are now able to prevent PCP with drugs, or to treat it quickly if it occurs. Death from PCP is now rare among people with HIV in the UK.
The real problems Even though there are now more powerful anti-HIV treatments, which can suppress the progress of HIV infection, living with the knowledge of a serious and potentially life-threatening infection can be stressful and difficult. Someone with HIV man remain in good physical health for many years but misunderstandings and fears about HIV are still widespread in society. People living with the virus may encounter hostility or rejection even from friends and family. Some have lost jobs and homes due to their employers' or landlords' attitudes, and children with HIV have been banned from schools.
Many people with HIV have seen friends and partners become ill before them, and may have seen them die. Some communities have been particularly affected by HIV; for example, gay men, people from sub-Saharan Africa and injecting drug-users. In some parts of the world, and among some African communities in the UK, it is not unusual for whole families to die from HIV. Many HIV positive people choose to tell no one about their diagnosis except for a few trusted friends, and this burden of secrecy can be very hard to bear. Living with the knowledge that you could pass a serious infection to someone else can also be very hard. A number of support groups have been set up around the country to help counter the isolation which HIV can cause and to help people make changes in their lives to cope with living with HIV. For further information and details on support groups call THT Direct on 0845 1221 200 (UK).
|
|
Last updated: 7 October 2004 |
