When 59-year-old Ashley was in hospital with appendicitis, neither Ashley nor the doctors considered HIV.
"They said there's nothing wrong with you, you've had a virus - not knowing that I'd still got the biggest virus you could possibly get," Ashley recalls.
Ashley was diagnosed with HIV three years ago, after having unprotected sex.
But the late diagnosis meant the virus had already started to damage Ashley's immune system.
"It was pretty much touch and go."
Ashley's experience isn't unusual - six out of 10 over-50s with HIV received a late diagnosis in 2018, according to figures from Public Health England (PHE).
Health professionals and charities say both the stigma and misconception that older people are not sexually active means symptoms are not always picked up.
"Over-50s, people who've come out of divorce, or marriage, they think they're safe," Ashley says.
"Because nobody can get pregnant anymore, 'there's no danger'.
"Because 'those illnesses are for young people'. But they're not, they're for everybody."
'You think you're invincible'
Figures obtained by the Victoria Derbyshire programme from PHE show rates of sexually transmitted infections (STIs) in the over-45s have increased by about a third in the past five years.
Norah O'Brien, a sexual health expert from PHE, says older people themselves often don't perceive themselves to be at risk.
It is a view echoed by 63-year-old Karen Norton, who contracted HIV a number of years ago in Africa.
"The majority of us all believe we're invincible and it'll never happen to us," she says.
"Professionals sort of assume that an over 50-year-old wouldn't have this illness.
"It's an assumption that I think is generally something we all make about over 50-year-olds.
"You don't really like to think of your mother or father having this - but it's so possible."
Karen took a long time to open up about her diagnosis, fearing she would be judged.
"You feel as if you're carrying a dirty secret that you have to hide," she says.
"If you have unprotected sex then it can happen to you. I'm a living example."
'Not a death sentence'
Last month, figures showed the number of people diagnosed with HIV in the UK had dropped substantially since 2012 - particularly among gay and bisexual men.
In response, the Terrence Higgins Trust said a focus was now needed beyond communities stereotypically associated with HIV.
Aled Osborne, from Brigstowe, which is a Bristol-based charity supporting people affected by HIV, says those in the over-50s bracket may wrongly believe HIV is a "gay disease".
Older people still remember the HIV/Aids campaigns of the 80s and 90s, he says, and they haven't necessarily received correct information since.
"Living with HIV now is not the death sentence it was in the 80s and 90s. We have effective treatment," he said.
"People living with HIV who are on effective treatment cannot pass the virus on."
The life expectancy of those prescribed anti-retroviral drugs at an early stage is in line with that of the general population.
But late-stage infections have more than a tenfold increased risk of death in the year following diagnosis compared with those who are diagnosed early and begin treatment immediately.
Ashley has struggled with the late diagnosis.
"I didn't mind being HIV positive. I don't mind it at all. But it was just that delay - that they didn't find it," Ashley says.
"It was so long… and the damage done to my body - I'm a little bit bitter about."