Post by admin on Aug 26, 2007 1:57:05 GMT -5
Acquired immune deficiency syndrome (AIDS) is a disease of the immune system caused by the human immunodeficiency virus (HIV). AIDS means that a person's immune system has been weakened so much by HIV that it cannot fight off certain serious infections and illnesses.
HIV is infectious and is usually passed from person to person by unprotected sex, sharing injection equipment or from a pregnant mother to her baby. In the UK, there are around 5,500 new infections per year.
HIV
Although there is no cure for HIV infection and AIDS, treatment with anti-HIV drugs dramatically slows the progress of the disease and has caused the number of AIDS deaths to plummet.
In the UK, most people with HIV lead full and active lives. In the developing world, where access to HIV drugs is limited, AIDS is one of the commonest causes of death.
HIV and the immune system
The immune system protects your body against infection. Its main component is white blood cells. These cells hunt out and destroy invading germs, including bacteria and viruses, preventing the development of serious diseases and damage to the body.
HIV avoids being destroyed by the immune system by repeatedly changing its outer "coat". It multiplies (replicates) within a special type of white blood cells called CD4 cells. These cells are normally involved in helping other types of immune cell to attack and destroy disease-causing germs.
As HIV multiplies, it destroys CD4 cells, so that the number of these cells declines. The loss of CD4 cells means that the body's ability to fight off infection is weakened.
AIDS
Once the immune system has been damaged, opportunistic infections begin to appear. The commonest infection is a type of pneumonia, a serious lung infection. Having certain serious infections marks the difference between HIV and AIDS.
Other AIDS symptoms can include:
various cancers
weight loss
fungal, bacterial or viral infections
dementia
How is HIV passed on?
HIV is found within some body fluids. These include blood, semen, breast milk and girl thingyl fluids. It is not found in saliva, sweat, urine or on the skin.
HIV is passed on when the virus from an infected person gets into the bloodstream of someone else. This can occur during unprotected anal or girl thingyl sex between same-sex or heterosexual couples. The risk of this happening is dramatically reduced by using a condom (see the BUPA factsheet, Sexually transmitted infections). There is a small chance of infection through unprotected oral sex, although the exact size of this risk is unclear. No method of barrier protection completely eliminates the risk.
HIV can also be passed on when people use dirty needles for injections or tattoos. This can be avoided by using single-use or sterilised needles. People who inject drugs can avoid infection by never sharing injection equipment.
A person can pass the virus on when the levels are high enough in the blood or other body fluids. This usually occurs within three months of infection. Because the early symptoms of HIV are not always obvious, a person may be able to pass on the virus before they realise that they have infected.
HIV cannot be passed on through normal day-to-day contact, such as sharing cutlery, sitting on toilet seats or by shaking hands.
HIV and pregnancy
The virus can be passed on from an infected mother to her baby, during pregnancy, childbirth or breastfeeding.
An HIV test is offered to all pregnant women early on in their pregnancy. If the test is positive, women are offered treatments that can reduce the chance of transmission. These include HIV drugs taken by the mother during pregnancy, delivery and breastfeeding, and drug treatment for the baby in the first few months of life. Mothers with HIV need to consider alternatives to breastfeeding to prevent transmission of the virus.
HIV and blood donation
In the past, people have become infected with HIV through blood or organ donations. Since 1985, all donations in the UK have been screened for HIV, so the chances of this happening are now extremely low.
HIV in the UK
The number of people living with HIV in the UK has increased steadily since the virus was discovered in the early 1980s. Official figures for 2002 put this at nearly 50,000 people. Of infections acquired in the UK, men who have sex with men remain at the highest risk of infection. However, transmission of the virus through heterosexual contact is on the increase.
Testing for HIV
Testing for HIV is carried out by looking at a blood sample for HIV antibodies, the body's defence chemicals produced in response to infection. These can be detected from around three months after infection. Before this time their levels may be too low.
Testing is usually carried out at the genito-urinary medicine (GUM) clinic of a local hospital, where sexually transmitted infections are diagnosed and treated. Although some clinics offer same-day testing, results are usually available after a week.
Although there are powerful and effective treatments that slow the progression of the disease, it can be difficult for people to come to terms with being diagnosed as HIV positive. For this reason, the decision to take an HIV test can be difficult.
Currently, most people who take an HIV test see a counsellor before having the blood test. The test is explained and the implications of a possible positive diagnosis are discussed.
Living with HIV
People with HIV are said to be HIV-positive. Most HIV-positive people appear to be completely healthy until their immune system is seriously damaged. This incubation period can last up to 10 years. During this time, they can pass the virus on, even though they may be unaware they are positive.
Treatment
HIV treatment is managed by specialist outpatient clinics, staffed by doctors, nurses and other health professionals. Patients are usually seen every few months, when the status of their immune system and their general health is reviewed.
Once the number of CD4 cells has fallen to a low level, or if the amount of virus in the blood is very high, the specialist may recommend starting drug treatment. All treatment decisions are made jointly with the specialist.
Current treatments prevent the virus from replicating in the body. This in turn reduces the amount of virus in the blood and allows the immune system to recover. To achieve this, two or more "antiretroviral" drugs must be taken. They normally have to be taken between one and three times a day and at specific times. This combination therapy is termed highly-active antiretroviral therapy (HAART) and has dramatically cut the number of deaths from AIDS since its introduction in 1996. There are three main classes of antiretroviral drug. Combination therapies usually contain drugs from two of these classes.
Nucleoside reverse transcriptase inhibitors (NRTIs) prevent HIV from copying its genetic information and so multiplying. They include AZT (Retrovir), which was the first ever anti-HIV drug. When first used on its own, AZT had serious side-effects. Now it is used in much lower doses in combination with other drugs.
Protease inhibitors (PIs) prevent the virus from assembling its protective coat before leaving CD4 cells. They include saquinavir (Invirase; Fortovase) and ritonavir (Norvir).
Non-nucleoside reverse transcriptase inhibitors (NNRTIs) are a newer, highly effective class of drug, which have a similar mode of action to NRTIs. They include efavirenz (Sustiva) and nevirapine (Viramune).
A new class of antiretroviral drug, known as an HIV fusion-inhibitor has recently been launched and will initially be used for people whose disease is no longer controlled by other treatments. At present there is just one fusion- inhibitor, enfuvirtide (Fuzion).
Side-effects
Despite the benefits of these new drug combinations, they often cause side-effects. In the first few months of treatment, people may experience nausea, vomiting and headaches, although these often wear off. Some drugs can cause sleep disturbances or depression. Protease inhibitors have been associated with a syndrome called lipodystrophy, which involves a thinning of the face, arms and legs, and a build-up of fat in the belly and on the back. Treatments for these side-effects are being developed.
In the future, further classes of anti-HIV drug may be produced. These may include drugs that stimulate the patient's own immune system to fight off HIV. There are also real hopes that a cure for HIV infection and a vaccine to prevent infection will be developed.
Further information
Terrence Higgins Trust
0845 1221 200
www.tht.org.uk
NAM (National AIDS Manual)
020 7840 0050
www.aidsmap.com
HIV is infectious and is usually passed from person to person by unprotected sex, sharing injection equipment or from a pregnant mother to her baby. In the UK, there are around 5,500 new infections per year.
HIV
Although there is no cure for HIV infection and AIDS, treatment with anti-HIV drugs dramatically slows the progress of the disease and has caused the number of AIDS deaths to plummet.
In the UK, most people with HIV lead full and active lives. In the developing world, where access to HIV drugs is limited, AIDS is one of the commonest causes of death.
HIV and the immune system
The immune system protects your body against infection. Its main component is white blood cells. These cells hunt out and destroy invading germs, including bacteria and viruses, preventing the development of serious diseases and damage to the body.
HIV avoids being destroyed by the immune system by repeatedly changing its outer "coat". It multiplies (replicates) within a special type of white blood cells called CD4 cells. These cells are normally involved in helping other types of immune cell to attack and destroy disease-causing germs.
As HIV multiplies, it destroys CD4 cells, so that the number of these cells declines. The loss of CD4 cells means that the body's ability to fight off infection is weakened.
AIDS
Once the immune system has been damaged, opportunistic infections begin to appear. The commonest infection is a type of pneumonia, a serious lung infection. Having certain serious infections marks the difference between HIV and AIDS.
Other AIDS symptoms can include:
various cancers
weight loss
fungal, bacterial or viral infections
dementia
How is HIV passed on?
HIV is found within some body fluids. These include blood, semen, breast milk and girl thingyl fluids. It is not found in saliva, sweat, urine or on the skin.
HIV is passed on when the virus from an infected person gets into the bloodstream of someone else. This can occur during unprotected anal or girl thingyl sex between same-sex or heterosexual couples. The risk of this happening is dramatically reduced by using a condom (see the BUPA factsheet, Sexually transmitted infections). There is a small chance of infection through unprotected oral sex, although the exact size of this risk is unclear. No method of barrier protection completely eliminates the risk.
HIV can also be passed on when people use dirty needles for injections or tattoos. This can be avoided by using single-use or sterilised needles. People who inject drugs can avoid infection by never sharing injection equipment.
A person can pass the virus on when the levels are high enough in the blood or other body fluids. This usually occurs within three months of infection. Because the early symptoms of HIV are not always obvious, a person may be able to pass on the virus before they realise that they have infected.
HIV cannot be passed on through normal day-to-day contact, such as sharing cutlery, sitting on toilet seats or by shaking hands.
HIV and pregnancy
The virus can be passed on from an infected mother to her baby, during pregnancy, childbirth or breastfeeding.
An HIV test is offered to all pregnant women early on in their pregnancy. If the test is positive, women are offered treatments that can reduce the chance of transmission. These include HIV drugs taken by the mother during pregnancy, delivery and breastfeeding, and drug treatment for the baby in the first few months of life. Mothers with HIV need to consider alternatives to breastfeeding to prevent transmission of the virus.
HIV and blood donation
In the past, people have become infected with HIV through blood or organ donations. Since 1985, all donations in the UK have been screened for HIV, so the chances of this happening are now extremely low.
HIV in the UK
The number of people living with HIV in the UK has increased steadily since the virus was discovered in the early 1980s. Official figures for 2002 put this at nearly 50,000 people. Of infections acquired in the UK, men who have sex with men remain at the highest risk of infection. However, transmission of the virus through heterosexual contact is on the increase.
Testing for HIV
Testing for HIV is carried out by looking at a blood sample for HIV antibodies, the body's defence chemicals produced in response to infection. These can be detected from around three months after infection. Before this time their levels may be too low.
Testing is usually carried out at the genito-urinary medicine (GUM) clinic of a local hospital, where sexually transmitted infections are diagnosed and treated. Although some clinics offer same-day testing, results are usually available after a week.
Although there are powerful and effective treatments that slow the progression of the disease, it can be difficult for people to come to terms with being diagnosed as HIV positive. For this reason, the decision to take an HIV test can be difficult.
Currently, most people who take an HIV test see a counsellor before having the blood test. The test is explained and the implications of a possible positive diagnosis are discussed.
Living with HIV
People with HIV are said to be HIV-positive. Most HIV-positive people appear to be completely healthy until their immune system is seriously damaged. This incubation period can last up to 10 years. During this time, they can pass the virus on, even though they may be unaware they are positive.
Treatment
HIV treatment is managed by specialist outpatient clinics, staffed by doctors, nurses and other health professionals. Patients are usually seen every few months, when the status of their immune system and their general health is reviewed.
Once the number of CD4 cells has fallen to a low level, or if the amount of virus in the blood is very high, the specialist may recommend starting drug treatment. All treatment decisions are made jointly with the specialist.
Current treatments prevent the virus from replicating in the body. This in turn reduces the amount of virus in the blood and allows the immune system to recover. To achieve this, two or more "antiretroviral" drugs must be taken. They normally have to be taken between one and three times a day and at specific times. This combination therapy is termed highly-active antiretroviral therapy (HAART) and has dramatically cut the number of deaths from AIDS since its introduction in 1996. There are three main classes of antiretroviral drug. Combination therapies usually contain drugs from two of these classes.
Nucleoside reverse transcriptase inhibitors (NRTIs) prevent HIV from copying its genetic information and so multiplying. They include AZT (Retrovir), which was the first ever anti-HIV drug. When first used on its own, AZT had serious side-effects. Now it is used in much lower doses in combination with other drugs.
Protease inhibitors (PIs) prevent the virus from assembling its protective coat before leaving CD4 cells. They include saquinavir (Invirase; Fortovase) and ritonavir (Norvir).
Non-nucleoside reverse transcriptase inhibitors (NNRTIs) are a newer, highly effective class of drug, which have a similar mode of action to NRTIs. They include efavirenz (Sustiva) and nevirapine (Viramune).
A new class of antiretroviral drug, known as an HIV fusion-inhibitor has recently been launched and will initially be used for people whose disease is no longer controlled by other treatments. At present there is just one fusion- inhibitor, enfuvirtide (Fuzion).
Side-effects
Despite the benefits of these new drug combinations, they often cause side-effects. In the first few months of treatment, people may experience nausea, vomiting and headaches, although these often wear off. Some drugs can cause sleep disturbances or depression. Protease inhibitors have been associated with a syndrome called lipodystrophy, which involves a thinning of the face, arms and legs, and a build-up of fat in the belly and on the back. Treatments for these side-effects are being developed.
In the future, further classes of anti-HIV drug may be produced. These may include drugs that stimulate the patient's own immune system to fight off HIV. There are also real hopes that a cure for HIV infection and a vaccine to prevent infection will be developed.
Further information
Terrence Higgins Trust
0845 1221 200
www.tht.org.uk
NAM (National AIDS Manual)
020 7840 0050
www.aidsmap.com