Getting tested for HIV means that, if you do have HIV, you can start your treatment before the infection damages your body and health. This is known as an early diagnosis.
Why you should get tested for HIV early
It's important to get tested for HIV early because, although you might look and feel healthy, the infection will be damaging your health. Left undiagnosed, you will also be at risk of passing HIV on to others.
Mandy Tyson, executive director for services, clinical and new business at HIV charity the Terrence Higgins Trust (THT), says: "If the infection is diagnosed early, when a person is fit and well, and they get treatment and care, we're looking at normal life expectancy. But they've got to be getting treatment and care, and it's got to start early."
It's estimated that 103,700 people in the UK have HIV. Around 17% of these - 18,100 in total - don't know they have it and are at risk of passing the virus on to others. They're also unable to benefit from effective treatments.
HIV is passed on through bodily fluids (such as blood, semen or vaginal fluid) through, for example, sex without a condom or through sharing needles to inject drugs.
Read about the causes of HIV.
Where to get an HIV test
The only way to know whether you have HIV is to have an HIV test. You shouldn't feel worried about getting tested, because if you do have HIV, the sooner you find out, the better.
You can get tested by going to:
- sexual health clinics or genitourinary medicine (GUM) clinics at hospitals or in the community - find sexual health services near you
- your GP surgery - ask your doctor or practice nurse whether your surgery offers HIV testing
- some contraception and young people's clinics
- Rapid testing clinics run by the THT
- a private clinic
- an antenatal clinic - if you're pregnant
- local drugs agencies - if you're an injecting drug user
People at increased risk of HIV, including men who have sex with men and black African communities, can also get a free HIV self-sampling test, which can be done at home.
It's up to you where you feel most comfortable being tested.
Why early diagnosis and treatment of HIV matters
Once HIV is in a person's body, the virus infects and destroys cells called CD4 cells in the blood. CD4 cells are responsible for fighting infection and are vital to your immune system.
A healthy adult who doesn't have HIV will normally have a CD4 count of 600 to 1,200.
If you have HIV, doctors will regularly test your blood to see how your immune system is doing. The tests measure the number of CD4 cells in your blood (your CD4 count) and the amount of HIV in your blood (the viral load).
Your doctor will know when it's best for you to start HIV treatment, which is usually given as a combination of tablets. Starting treatment can raise your CD4 count and lower your viral load.
"The latest research shows the benefits of starting treatment as soon as possible," says Tyson. "When the CD4 gets down to 200, opportunistic infections can start, such as tuberculosis, oral thrush, Kaposi's sarcoma and pneumonia.
"Starting treatment early means that HIV won't continue to damage the immune system, and people won't be at risk of these opportunistic infections."
Why late HIV diagnosis is serious
If HIV isn't treated, it will eventually damage your immune system so much that you're likely to develop a serious, life-threatening condition, such as pneumonia. It typically takes about 5 to 10 years for the virus to damage the immune system in this way.
If you're diagnosed with HIV at this stage - known as late diagnosis - antiretroviral drug treatment will work. However, the overall outlook for your health may be affected. In 2013, 42% of adults diagnosed with HIV in the UK were diagnosed late.
"The vast majority of people who die from HIV are those who are diagnosed late," says Tyson. "When people aren't diagnosed with HIV until they present late, at A&E or their GP with symptoms of a serious infection, it can affect their prognosis."
You can protect yourself against HIV by using a condom every time you have vaginal, anal or oral sex. This will also help to prevent you passing on the infection, if you have it.
If you're living with HIV, being on successful treatment and having an undetectable viral load will also make it unlikely that you will pass on the virus to any sexual partners. However, it is still important to practise safe sex.
If you're worried you have been exposed to HIV, there is a course of treatment called post-exposure prophylaxis (PEP). This can help to prevent an HIV infection developing after the virus has entered the body, if you take it soon enough.
You need to take PEP as soon as possible after the exposure risk - ideally within 24 hours, but no later than 72 hours. You can get PEP from any A&E department or sexual health or GUM clinics.
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Article provided by NHS Choices