HIV is a virus (human immunodeficiency virus) that attacks the immune system, and weakens your ability to fight infections and disease. It’s most commonly caught by having sex without a condom.
Apart from having sex HIV can also be passed on by sharing infected needles and other injecting equipment, and from an HIV-positive mother to her child during pregnancy, birth and breastfeeding.
HIV stands for human immunodeficiency virus. The virus attacks the immune system, and weakens your ability to fight infections and disease.
There is no cure for HIV, but there are treatments to enable most people with the virus to live a long and healthy life.
AIDS is the final stage of HIV infection, when your body can no longer fight life-threatening infections. With early diagnosis and effective treatment, most people with HIV will not go on to develop AIDS.
Where did HIV come from?
Scientists identified a type of chimpanzee in West Africa as the source of HIV infection in humans. They believe that the chimpanzee version of the immunodeficiency virus (called simian immunodeficiency virus or SIV) most likely was transmitted to humans and mutated into HIV when humans hunted these chimpanzees for meat and came into contact with their infected blood. Over decades, the virus slowly spread across Africa and later into other parts of the world.
The earliest known case of infection with HIV-1 in a human was detected in a blood sample collected in 1959 from a man in Kinshasa, Democratic Republic of the Congo. (How he became infected is not known.) Genetic analysis of this blood sample suggested that HIV-1 may have stemmed from a single virus in the late 1940s or early 1950s.
We know that the virus has existed in the United States since at least the mid- to late 1970s. From 1979–1981 rare types of pneumonia, cancer, and other illnesses were being reported by doctors in Los Angeles and New York among a number of male patients who had sex with other men. These were conditions not usually found in people with healthy immune systems.
In 1982 public health officials began to use the term “acquired immunodeficiency syndrome,” or AIDS, to describe the occurrences of opportunistic infections, Kaposi’s sarcoma (a kind of cancer), and Pneumocystis jirovecii pneumonia in previously healthy people. Formal tracking (surveillance) of AIDS cases began that year in the United States.
In 1983, scientists discovered the virus that causes AIDS. The virus was at first named HTLV-III/LAV (human T-cell lymphotropic virus-type III/lymphadenopathy-associated virus) by an international scientific committee. This name was later changed to HIV (human immunodeficiency virus).
For many years scientists theorized as to the origins of HIV and how it appeared in the human population, most believing that HIV originated in other primates. Then in 1999, an international team of researchers reported that they had discovered the origins of HIV-1, the predominant strain of HIV in the developed world. A subspecies of chimpanzees native to west equatorial Africa had been identified as the original source of the virus. The researchers believe that HIV-1 was introduced into the human population when hunters became exposed to infected blood. (Source: The Aids Institute)
Symptoms of HIV
Most people who are infected with HIV experience a short, flu-like illness that occurs two to six weeks after infection. After this, HIV often causes no symptoms for several years.
The flu-like illness that often occurs a few weeks after HIV infection is also known as seroconversion illness. It’s estimated that up to 80% of people who are infected with HIV experience this illness.
The most common symptoms are:
- fever (raised temperature)
- sore throat
- body rash
Other symptoms can include:
- joint pain
- muscle pain
- swollen glands (nodes)
The symptoms usually last one to two weeks but can be longer. They are a sign that your immune system is putting up a fight against the virus.
However, these symptoms are most commonly caused by conditions other than HIV, and do not mean you have the virus.
If you have several of these symptoms, and you think you have been at risk of HIV infection within the past few weeks, you should get an HIV test.
After the initial symptoms disappear, HIV will often not cause any further symptoms for many years. During this time, known as asymptomatic HIV infection, the virus continues to be active and causes progressive damage to your immune system. This process can take about 10 years, during which you will feel and appear well.
Once the immune system becomes severely damaged symptoms can include:
- weight loss
- chronic diarrhoea
- night sweats
- skin problems
- recurrent infections
- serious life-threatening illnesses
Earlier diagnosis and treatment of HIV can prevent these problems.
It is recommended you should still take an HIV test if you have put yourself at risk at any time in the past, even if you experience no symptoms.
Want to know more?
Causes of HIV
In the UK, most cases of HIV are caused by having sex without a condom with a person who has HIV.
A person with HIV can pass the virus to others whether or not they have any symptoms. People with HIV are more infectious in the weeks following infection.
HIV treatment significantly reduces the risk of someone with HIV passing it on.
According to Public Health England, 95% of people diagnosed with HIV in the UK in 2011 acquired HIV through sexual contact.
The main routes of transmission are unprotected vaginal and anal sex. It is also possible to catch HIV through unprotected oral sex, but the risk is much lower.
The risk of HIV transmission through oral sex will be higher if the person giving oral sex has mouth ulcers, sores or bleeding gums and/or if the person receiving oral sex has been recently infected with HIV (and has a lot of the virus in their body) or another sexually transmitted infection.
The type of sex also makes a difference to the level of risk:
- performing oral sex on a man with HIV carries some risk, particularly if he ejaculates (comes) in your mouth
- it is possible to catch HIV by performing oral sex on a woman with HIV, particularly if she is having a period, although this is considered to be extremely low risk
- receiving oral sex from someone who has HIV is also extremely low risk as HIV is not transmitted through saliva
Other risk behaviours
Other ways of getting HIV include:
- sharing needles, syringes and other injecting equipment
- from mother to baby before or during birth or by breastfeeding
- sharing sex toys with someone infected with HIV
- healthcare workers accidentally pricking themselves with an infected needle (this risk is extremely low)
- blood transfusion (now very rare in the UK, but still a problem in developing countries)
How is HIV transmitted
HIV is not passed on easily from one person to another. The virus does not spread through the air like cold and flu viruses.
HIV lives in the blood and in some body fluids. To get HIV, one of these fluids from someone with HIV has to get into your blood.
The body fluids that contain enough HIV to infect someone are:
- vaginal fluids, including menstrual blood
- breast milk
- lining inside the anus
Other body fluids, like saliva, sweat or urine, do not contain enough of the virus to infect another person.
The main ways the virus enters the bloodstream are:
- by injecting into the bloodstream (with a contaminated needle or injecting equipment)
- through the thin lining on or inside the anus and genitals
- through the thin lining of the mouth and eyes
- via cuts and sores in the skin
HIV is not passed on through:
- being bitten
- contact with unbroken, healthy skin
- being sneezed on
- sharing baths, towels or cutlery
- using the same toilets or swimming pools
- mouth-to-mouth resuscitation
- contact with animals or insects such as mosquitoes
How HIV infects the body
HIV infects cells of the immune system, the body’s defence system, causing progressive damage and eventually making it unable to fight off infections.
The virus enters cells in the immune system called CD4 cells + ve lymphocyte cells, which protect the body against various bacteria, viruses and other germs.
It uses the CD4 cells to make thousands of copies of itself. These copies then leave the CD4 cells, killing them in the process.
This process continues until eventually the number of CD4 cells, also called your CD4 count, drops so low that your immune system stops working.
This can take about 10 years, during which time you will feel and appear well.
Who is most at risk?
People who are at higher risk of becoming infected with HIV include:
- men who have had unprotected sex with men
- women who have had sex without a condom with men who have sex with men
- people who have had sex without a condom with a person who has lived or travelled in Africa
- people who inject drugs
- people who have had sex without a condom with somebody who has injected drugs
- people who have caught another sexually transmitted infection
- people who have received a blood transfusion while in Africa, eastern Europe, the countries of the former Soviet Union, Asia or central and southern America
The only way to find out if you have HIV is to have an HIV test, as symptoms of HIV may not appear for many years.
HIV testing is provided to anyone free of charge on the NHS. Many clinics can give you the result on the same day and home-testing and home-sampling kits are also available.
Who should get tested?
Anyone who thinks they could have HIV should get tested.
Certain groups of people are at particularly high risk and are advised to have regular tests. For example:
- men who have sex with men are advised to have an HIV test at least once a year, or every three months if they’re having unprotected sex with new or casual partners
- black African men and women are advised to have an HIV test, and a regular HIV and STI screen, if they’re having unprotected sex with new or casual partners
Other people at an increased risk of infection include those who share needles, syringes or other injecting equipment. Read more about how you get HIV.
When should I get tested?
Seek medical advice immediately if you think there’s a chance you could have HIV. The earlier it’s diagnosed, the earlier you can start treatment and avoid becoming seriously ill.
Some HIV tests may need to be repeated one to three months after exposure to HIV infection, but you shouldn’t wait this long to seek help. Your GP or a sexual health professional can talk to you about having a test and discuss whether you should take emergency HIV medication.
Anti-HIV medication, called PEP (post-exposure prophylaxis) may stop you becoming infected if taken within 72 hours of being exposed to the virus.
Where can I get an HIV test?
There are various places you can go to for an HIV test, including:
- sexual health or genitourinary medicine (GUM) clinics
- clinics run by charities such as the Terrence Higgins Trust
- some GP surgeries
- some contraception and young people’s clinics
- local drug dependency services
- an antenatal clinic, if you’re pregnant
- a private clinic, where you will have to pay
There are also home-sampling and home-testing kits (see below) you can use if you don’t want to visit any of these places.
Types of HIV test
There are four main types of HIV test:
- Full blood test – where a sample of blood is taken in a clinic and sent for testing in a laboratory. Results are usually available within a few days.
- “Point of care” test – where a sample of saliva from your mouth or a small spot of blood from your finger is taken in a clinic. This sample doesn’t need to be sent to a laboratory and the result is available within a few minutes.
- Home-sampling kit – where you collect a saliva sample or small spot of blood at home and send it off in the post for testing. You’ll be contacted by phone or text with your result in a few days. Visit Test.HIV to check if you’re eligible for a free test. If not, you can buy them online or from some pharmacies.
- Home-testing kit – where you collect a saliva sample or small spot of blood yourself and test it at home. The result is available within minutes. It’s important to check that any test you buy has a CE quality assurance mark and is licensed for sale in the UK, as poor quality HIV self-tests are available from overseas.
If the test finds no sign of infection, your result is “negative”. If signs of infection are found, the result is “positive”.
The full blood test is the most accurate test and can normally give reliable results from one month after infection. The other tests tend to be less accurate and may not give a reliable result for a longer period after exposure to the infection (this is known as the “window period”).
For all these tests, a full blood test should be carried out to confirm the result if the first test is positive. If this test is also positive, you’ll be referred to a specialist HIV clinic for some more tests and a discussion about your treatment options.
Screening for HIV in pregnancy
All pregnant woman are offered a blood test to check if they have HIV as part of routine antenatal screening.
If untreated, HIV can be passed from a pregnant woman to her baby during pregnancy, birth or breastfeeding. Treatment in pregnancy greatly reduces the risk of passing on HIV to the baby.
Read more about screening for HIV during pregnancy.
There is no cure for HIV, but there are treatments to enable most people with the virus to live a long and healthy life.
Emergency HIV drugs
If you think you have been exposed to the virus within the last 72 hours (three days), anti-HIV medication may stop you becoming infected.
For it to be effective, the medication, called post-exposure prophylaxis or PEP, must be started within 72 hours of coming into contact with the virus. It is only recommended following higher risk exposure, particularly where the sexual partner is known to be positive.
The quicker PEP is started the better, ideally within hours of coming into contact with HIV. The longer the wait, the less chance of it being effective.
PEP has been misleadingly popularised as a “morning-after pill” for HIV – a reference to the emergency pill women can take to prevent getting pregnant after having unprotected sex.
But the description is not accurate. PEP is a month-long treatment, which may have serious side effects and is not guaranteed to work. The treatment involves taking the same drugs prescribed to people who have tested positive for HIV.
You should be able to get PEP from:
- sexual health clinics, or genitourinary medicine (GUM) clinics
- hospitals – usually accident and emergency (A&E) departments
If you already have HIV, try your HIV clinic if the PEP is for someone you’ve had sex with.
Want to know more?
- Terrence Higgins Trust: post-exposure prophylaxis (PEP)
If you test positive
If you are diagnosed with HIV, you will have regular blood tests to monitor the progress of the HIV infection before starting treatment.
This involves monitoring the amount of virus in your blood (viral blood test) and the effect HIV is having on your immune system. This is determined by measuring your levels of CD4+ve lymphocyte cells in your blood. These cells are important for fighting infection.
Treatment is usually recommended to begin when your CD4 cell count falls towards 350 or below, whether or not you have any symptoms. In some people with other medical conditions, treatment may be started at higher CD4 cell counts. When to start treatment should be discussed with your doctor.
The aim of the treatment is to reduce the level of HIV in the blood, allow the immune system to repair itself and prevent any HIV-related illnesses.
If you are on HIV treatment, the level of the virus in your blood is generally very low and it is unlikely that you will pass HIV on to someone else.
If you have another condition
Treatment is recommended to begin at any CD4 count if you are on radiotherapy or chemotherapy that will suppress your immune system, or if you have been diagnosed with certain other illnesses, including:
HIV is treated with antiretrovirals (ARVs), these work by stopping the virus replicating in the body, allowing the immune system to repair itself and preventing further damage.
A combination of ARVs is used because HIV can quickly adapt and become resistant to one single ARV.
Patients tend to take three or more types of ARV medication. This is known as combination therapy or antiretroviral therapy (ART).
Some antiretroviral drugs have been combined into one pill, known as a “fixed dose combination”. This means that the most common treatments for people just diagnosed with HIV involve taking just one or two pills a day.
Different combinations of ARVs work for different people so the medicine you take will be individual to you.
Once HIV treatment is started, you will probably need to take the medication for the rest of your life. For the treatment to be continuously effective, it will need to be taken regularly every day. Not taking ARVs regularly may cause the treatment to fail.
Many of the medicines used to treat HIV can interact with other medications prescribed by your GP or bought over-the-counter. These include herbal remedies such as St John’s Wort, as well as recreational drugs.
Always check with your HIV clinic staff or your GP before taking any other medicines.
Want to know more?
- Terrence Higgins Trust: Treatment for HIV
ARV treatment is available to prevent a pregnant woman from passing HIV to her child.
Without treatment, there is a one in four chance your baby will become infected with HIV. With treatment, the risk is less than one in 100.
Advances in treatment mean there is no increased risk of passing the virus to your baby with a normal delivery. However, for some women, a caesarean section may still be recommended.
If you have HIV, do not breastfeed your baby because the virus can be transmitted through breast milk.
If you or your partner has HIV, speak to an HIV doctor as there are options for safely conceiving a child without putting either of you at risk of infection.
Missing a dose
HIV treatment only works if you take your pills regularly every day. Missing even a few doses will increase the risk of your treatment not working.
You will need to develop a daily routine to fit your treatment plan around your lifestyle.
HIV treatment can have side effects. If you get serious side effects (which is uncommon) you may need to try a different combination of ARVs.
Common side effects include:
- skin rashes
- sleep difficulties
The best way to prevent HIV is to use a condom for sex and to never share needles or other injecting equipment (including syringes, spoons and swabs).
If you have HIV, you can pass it on to others if you have sex without a condom, or share needles, syringes, or other injecting equipment.
HIV treatment with ART substantially reduces the risk of passing the virus onto someone else.
Knowing your HIV status and that of your partner is important and if you are at regular risk of potential exposure to HIV you should have a regular HIV test.
HIV can be transmitted by having vaginal or anal sex without a condom. There is also a risk of transmission through oral sex, but this risk is much lower.
HIV can also be caught from sharing sex toys with someone infected with HIV.
See causes of HIV for more on transmission of HIV.
The best way to prevent HIV and other sexually transmitted infections (STIs) is to use a condom for penetrative sex and a dental dam for oral sex.
Condoms come in a variety of colours, textures, materials and flavours. Both male and female condoms are available.
A condom is the most effective form of protection against HIV and other STIs. It can be used for vaginal and anal sex, and for oral sex performed on men.
HIV can be passed on before ejaculation, through pre-come and vaginal secretions, and from the anus.
It is very important that condoms are put on before any sexual contact occurs between the penis, vagina, mouth or anus.
Lubricant, or lube, is often used to enhance sexual pleasure and safety, by adding moisture to either the vagina or anus during sex.
Lubricant can make sex safer by reducing the risk of vaginal or anal tears caused by dryness or friction, and it can also prevent a condom from tearing.
Only water-based lubricant (such as K-Y Jelly) rather than an oil-based lubricant (such as Vaseline or massage and baby oil) should be used with condoms.
Oil-based lubricants weaken the latex in condoms and can cause them to break or tear.
A dental dam is a small sheet of latex that works as a barrier between the mouth and the vagina or anus to reduce the risk of STIs during oral sex.
Sharing needles and injecting equipment
If you inject drugs, don’t share needles or syringes, or other injecting equipment such as spoons and swabs, as this could expose you to HIV and other viruses found in the blood, such as hepatitis C.
Many local authorities and pharmacies offer needle exchange programmes, where used needles can be exchanged for clean ones.
If you are a heroin user, consider enrolling in a methadone programme. Methadone can be taken as a liquid, so it reduces your risk of getting HIV.
A GP or drug counsellor should be able to advise you about both needle exchange programmes and methadone programmes.
If you are having a tattoo or piercing, it’s important that a clean, sterilised needle is always used.
Screening for HIV in pregnancy
All pregnant women are offered a blood test to check if they have HIV as part of routine antenatal screening. If untreated, HIV can be passed from a pregnant woman to her baby during pregnancy, birth or breastfeeding. Treatment in pregnancy greatly reduces the risk of passing on HIV to the baby.
How people cope with being diagnosed with HIV, as well as with treatment, varies from person to person.
By properly managing your condition – taking your medication correctly and avoiding illness – you’ll be able to live as normal a life as possible.
Other issues to consider include getting psychological support, telling people about your HIV, pregnancy and financial support.
It’s important to take your medication on time, every time. Even missing one or two doses a week can increase your risk of developing resistance to the medication and your treatment not working. It can be helpful to develop a daily routine around taking your medication, so that you don’t forget to take it.
Many medicines used to treat HIV can interact with other medication, which may affect how they work or increase the risk of side effects.
It’s best to tell your HIV doctor or HIV pharmacy about all other medication you’re taking – including over-the-counter medications, supplements, and recreational drugs – to check they won’t interact with your HIV medication.
In addition to taking HIV medication, there are many things you can do to improve your general health and reduce your risk of falling ill including exercising regularly, eating a healthy, balanced diet and stopping smoking.
Reviewing your treatment
As HIV is a long-term condition, you’ll be in regular contact with your healthcare team, who will review your treatment on an ongoing basis.
Developing a good relationship with your healthcare team means that you can easily discuss your symptoms or concerns. The more the team knows, the more they can help you.
Services, including support organisations, may work together to provide specialist care and emotional support. Find local HIV support services.
If you have HIV, you should take extra precautions to prevent exposure to other infections.
Everyone with a long-term condition such as HIV is encouraged to get a flu jab each autumn to protect against seasonal flu (influenza).
It’s also recommended that they get a pneumoccocal vaccination. This is an injection that protects against a serious chest infection called pneumococcal pneumonia.
Psychological impact of HIV
Being diagnosed with HIV can be extremely distressing, and feelings of anxiety or depression are common. Your HIV clinic can provide you with counselling so that you can fully discuss your condition and your concerns.
You may find it helpful to talk to a trained counsellor or psychologist, or to someone at a specialist helpline. Your HIV clinic will have information about these.
Some people find it helpful to talk to other people who have HIV, either at a local support group or in an internet chatroom.