It began with a one-night stand. After he had unprotected sex with a partner who was HIV positive, photographer Edo Zollo feared he had contracted the virus himself. The experience led the 38-year-old to spend two years photographing scores of people in the UK who are living with HIV.

"It was a nightmare," Zollo says of his own health scare. "The next day, I was really worried. What was going to happen to me if I was HIV positive? I thought: 'I am going to die.' How would I tell my family? Would I be judged? It made me realise what the impact of living with HIV could be."

Zollo, who is originally from Italy but has lived in London for 12 years, spent a month on an intense drug combination. He was eventually given the all clear, but not before he had had a glimpse of the taboos surrounding HIV and Aids. He felt that he could not ignore what he had learned. "I wanted to do something about it. I wondered what it was like for people whose tests were positive. How did they feel?"

This year is the 30th anniversary of the death of Terrence Higgins, one of the first people to die of an Aids-related illness in the UK. So far more than 60 million people have been infected with the HIV virus worldwide, and about 30 million people have died of Aids, according to the World Health Organisation. In 2010, 91,500 people in the UK were thought to be living with HIV, says the National Aids Trust. Treatment has improved so much that people can now have a near to normal life expectancy if they are diagnosed early and receive treatment.

Yet although treatment may have improved, stigmas associated with the virus have not gone away, says Zollo, who hoped to address this with his project. "I thought, what about taking pictures of 30 people, to break down the stereotypes? HIV impacts on everybody."

He travelled from Glasgow to Bournemouth to meet his subjects, whose portraits are on show at the Reading Room gallery in Soho until January 2013. But it wasn't easy finding participants. "Apart from the 30 people in the exhibition, there were about 60 others who changed their minds when I told them it would be in a gallery, because they said it was too public."

But Zollo's perseverance paid off and all the stories shared are powerful. "The one that made the biggest impression was a heterosexual woman called Gemma who contracted the virus from an ex-boyfriend. She got pregnant, and the baby was born HIV positive. She was in such a negative spiral, the baby was taken away from her and put up for adoption. That broke my heart."

Others are more positive. "There is Maurice, who is 73 and has had HIV for 28 years. You can see from his photograph that he is still enjoying life." Zollo says he hopes the exhibition will overcome prejudices. "My hope is that people come to the exhibition and look at the pictures and story and say: 'That could be me.' The people in the pictures are normal and that's what I want to show."

• Stand Tall, Get Snapped is at the Reading Room Gallery, London W1 until 3 January 2013.