The NHS says one-in-four people with HIV don't know they have it
NHS officials say all patients diagnosed with HIV in Cornwall last year were suffering an advanced stage of the disease.
As a result, many of them were seriously ill and more likely to develop AIDS.
For World AIDS Day, the NHS in Cornwall is using the occasion to urge people to have tests, if there's any chance they could have contracted the virus.
The NHS says one-in-four people with HIV don't know it.
Veritee Reed-Hall, from west Cornwall, became HIV positive after her husband contracted it while working abroad.
Listen to a longer interview with Veritee exclusive to the BBC Cornwall website.
She says: "The assumption is you must have been a drug user, your husband must have been gay. It's not like that anymore. Anybody can get HIV. It's out there in the population."
Veritee says people should be routinely tested.
"It's not offered routinely as part of normal check ups. My personal opinion is it should be. If it was the stigma would be reduced as we'd all be having that test. It should be part of the routine well persons test."
Al Green is from Cornwall and the Isles of Scilly health promotion service. He says: "People think 'oh it won't happen to me, it's something that happens in London, Brighton, or Manchester'.
"But it can happen anywhere to anyone. So it's something we need to bear in mind living in Cornwall."
Over half of all people living with HIV are aged between 30 and 44, but there are significant numbers both of young people and older people now living with HIV.
Frequently Asked Questions
The following are some of the questions often asked about HIV and AIDS, according to worldaidsday.org.
What is HIV?
HIV is a virus that attacks the body's immune system - the body's defence against diseases.
Are HIV and AIDS the same?
No. When someone is described as living with HIV, they have the HIV virus in their body. A person is considered to have developed AIDS when the immune system is so weak it can no longer fight off a range of diseases with which it would normally cope.
World Aids Day facts
People living with HIV in the UK
The number of people living with HIV in the UK has trebled in the last 10 years
More than 90,000 people are living with HIV in the UK
Over a quarter of people with HIV in the UK are undiagnosed
About two thirds of people living with HIV are men and a third are women
How is HIV passed on?
HIV can be passed on through infected blood, semen, vaginal fluids or breast milk.
The most common ways HIV is passed on are:
Sex without a condom with someone living with HIV
Sharing infected needles, syringes or other injecting drug equipment
From an HIV-positive mother (to her child) during pregnancy, childbirth or breastfeeding (but with effective treatment and care the risk of transmission can be greatly reduced)
I don't know anyone with HIV... do I?
Today there are more people than ever before living with HIV in the UK, but less people report knowing someone with HIV. People with HIV generally look healthy and many do not find it easy to tell other people, so you may not realise if someone you know if HIV positive. To learn more about the different groups of people affected by HIV view the statistics.
Is there a cure for HIV?
No, but treatment can keep the virus under control and the immune system healthy. People on HIV treatment can live a healthy, active life, although they may experience side effects from the treatment. If HIV is diagnosed late, treatment may be less effective.
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