HIV and AIDS
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 canpass the virus to others even if they don't have any symptoms. People with HIV are also more infectiousin the weeks following infection.
HIV treatment significantly reduces the risk of someone with HIV passing it on.
Most people diagnosed with HIV in the UK acquire HIV through unprotected vaginal and anal sex.
It's also possible to catch HIV through unprotected oral sex, but the risk is much lower. The riskis higher if:
The type of sex also makes a difference to the level of risk:
Other waysof gettingHIV include:
People who are at higherrisk ofbecoming infected withHIV include:
HIV isn't passed on easily from one person to another. The virus doesn't 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:
Other body fluids, like saliva, sweat or urine, don't contain enough of the virus to infect another person.
The main ways the virus enters the bloodstream are:
HIV isn't passed on through:
HIV infects cells of the immune system, the bodys defence system, causing progressive damage and eventually making it unable to fight off infections.
The virus enters immune system cellscalled CD4+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 yourCD4 count, drops so low that your immune system stops working.
This can take about 10 years, during which time you'll feel and appear well.Read about the symptoms of HIV.
Read about HIV, a virus most commonly caught by having unprotected sex or by sharing infected needles and other injecting equipment to inject drugs.
Symptoms of early HIV infection, also called primary HIV infection or seroconversion, and AIDS (late-stage HIV infection).
Read about the causes of HIV, how it spreads, who's most at risk and its origins in Africa
Read about HIV testing, including when you should get tested, where you can get tested, and what the different tests involve.
Treatments for HIV, including post-exposure prophylaxis (PEP), antiretrovirals (ARVs), HIV and pregnancy, sperm washing, side effects and getting support.
Information for people living with HIV, including medication advice, how to stay healthy and reduce your risk of illness and where to find help and support.
Find out how to prevent passing on HIV to others by taking precautions, such as using a condom, when having penetrative vaginal or anal sex.
Sarah has HIV. She describes her pregnancy and the steps she had to take to ensure shed have a healthy baby. An expert explains what HIV is and how to avoid passing it on to your unborn child.
Tina Middleton caught HIV when she was just 20 years old from a partner with haemophilia.
Mick Mason, who has haemophilia, caught HIV and hepatitis in the early 1980s from contaminated blood products.
Michael Edwards contractedHIV in 1990. He is now 62 and is still working and leading a healthy life. The first sign was a bad dose of flu. Like me, my GP is