Leo found out he was HIV positive when he was 12. A few months later, in a personal, social and health education lesson, the teacher was discussing HIV and Aids: “And some of the pupils were joking around, and the teacher said: ‘Guys, it’s not funny! If you have HIV, you don’t have long to live. If you have HIV, you’re going to die.’”

Leo remembers trying to remain composed, but he couldn’t: what he’d heard was so shocking, so unexpected. His teacher noticed the tears running down his face, took him out of the classroom and asked: “What’s wrong?” And Leo said: “Is that what’s going to happen to me, sir? I’m HIV positive.”

The truth is that Leo isn’t, and never was, going to die. Like most of the 1,000 or so school-age children in the UK who are HIV positive, his condition is carefully monitored and well managed by drugs. What he heard from his teacher that day was incorrect: misinformation from someone in a trusted position who a pupil would usually expect to be correct.

Leo’s tale is one of many examples of how wrong schools often get it where HIV is concerned. Students have been humiliated and shocked in their own schools, and some are reported to have been excluded by their school on disclosure of their HIV status.

As well as causing distress to affected pupils, teachers’ misconceptions – when passed on to other children – ensure a new generation is, in turn, misinformed. All of which explains why the Children’s HIV Association (Chiva) is reissuing guidelines for schools this week, and why its projects manager, Magda Conway, says all teachers need to become much more aware of the issues around pupils who are HIV positive or who are affected by HIV through someone close to them. “Teachers aren’t a bad lot, we don’t want to vilify them, but many of them are very ill informed about this,” says Conway. One survey carried out by Chiva last year found that fewer than half of teachers were aware that mother-to-child transmission is the most common route of infection to children, and more than 50% believed HIV could be transmitted via spitting or biting.

“The problem is that many of them got their information about HIV from the notorious Aids campaign of the 1980s – the ‘Don’t die of ignorance’ campaign,” says Conway. That campaign, run at saturation levels by the Department of Health, featured crumbling mountains and a falling tombstone, and a voiceover that spoke of the virus as “a threat to us all”, the cause of “a deadly disease [with] no known cure”.

“Science has come on in leaps and bounds since then – today it’s a manageable health condition, and it needs to be treated that way. Too many teachers still base what they know on the ‘Don’t die of ignorance’ campaign.”

She says schools need to ensure that a pupil who discloses their HIV diagnosis will be sensitively and professionally supported. “If teachers become aware that a child in school is living with HIV, they need to understand that there is no risk to anyone else, and that confidentiality should be respected.” The revised guidelines spell out the most misunderstood key facts, including the crucial issue that HIV cannot be passed on through normal play and normal childhood interactions.

“No one has ever contracted HIV in school, period,” says Conway. “A pupil or a teacher living with HIV poses no risk whatsoever to the school community.”

Those with HIV, the guidelines spell out, can have every expectation of living long and happy lives. And confidentiality is essential to people living with HIV, due to the stigma that remains in society around the virus.

The biggest thing we’re fighting and the biggest problem for pupils is the stigma around HIV Magda Conway

In an attempt to step up awareness, Chiva took Leo and a group of other HIV-positive young people to a meeting at Westminster last week, where they shared their stories with MPs and peers.

Cece, 17, told how her boyfriend found out she was HIV positive and started spreading the story around the school. “I stopped taking my meds because I thought that would be a way of forgetting about it – everything seemed so awful,” she says. “When you’re HIV positive you live a double life, and at some point it’s going to cross over.” And what happened next? “You really find out who your friends are: a group of my friends got the kids together who knew and said, stop spreading these stories. But the point is that it should have been the teachers who did that, not the children.”

Sometimes the ignorance of teachers puts their better-informed pupils into a difficult situation, as happened to another pupil, Evie. “We were in a science lesson and the teacher was asked, how is the HIV virus passed on? And the teacher said, you can get it from kissing someone. And I knew, of course, that this wasn’t true, but I wasn’t able to put the teacher right because how could I have explained how I knew without disclosing my own HIV status, which it wouldn’t have been appropriate to do?”

As heartbreaking as Leo’s experience was that of Shona, who, like Leo, knew she was HIV positive but hadn’t disclosed it to her school. “I was in a humanities class and the teacher started going on about what HIV meant. She said if you have it, your life expectancy is probably going to be about 10 years. And I was in year 9 so about 13 at the time, and it was shocking and confusing. I thought, does that mean I’ll only live another 10 years? It wasn’t what I’d been told, but when you hear a teacher saying something like that, it makes you doubt what you thought you knew.”

Other youngsters told stories about overreaction on the part of their teachers when their status was disclosed. One boy talked of feeling alarm bells were ringing when he had a nose bleed; a girl spoke about how she was offered a nurse to talk to daily. “I said, I don’t need to talk to a nurse every day! I see enough nurses. I just want a normal life.”

The lack of good management for HIV-positive pupils means they sometimes miss out on, for example, school trips – as happened to Cece. “I wanted to go on a skiing trip to Austria when I was in year 8. It was 10 days away, and as soon as I told my mum she was like, how on earth can you do that? You have to take your medicines, you can’t go abroad.” Cece didn’t go on the trip. “But why should I have missed out? The truth is I could easily have gone on that trip if there had been proper support for me in the school.”

What schools need to provide, says Conway, is the potential for a pupil who is HIV positive to tell one trusted person. “You get some schools where it’s discovered that a pupil is HIV positive and there’s a kneejerk reaction based on ignorance. I’ve heard of pupils even being excluded – that happened as recently as 2013,” says Conway. In that instance it was a third party, a community worker, who disclosed the pupil’s HIV status to the school, which then took advice from a national teaching organisation – advice that turned out to be 25 years out of date. At another school she was told about, says Conway, the headteacher told an assembly that a pupil was HIV positive and was being excluded.

The National Association of Head Teachers is backing the Chiva campaign. Its president, Tony Draper, says schools need to make themselves safe places for children who are HIV positive. “They need to ensure that pupils can disclose their status to one person, and no one else needs to know,” he says. “At the moment, pupils are missing school for medical appointments without being able to tell anyone why they’re away. That needs to change.”

The truth is, says Conway, that the treatment of pupils with HIV should be the same as the treatment for any other pupil: there are no special requirements, except the need for one person they can feel confident in disclosing their status to, should they choose to. “The biggest thing we’re fighting is the stigma that surrounds HIV, and the biggest problem for pupils who live with HIV isn’t physical health issues, it’s mental health issues. Children who are HIV positive are more likely to have mental health problems, more likely to self-harm, and more likely to take their own lives. And that’s all connected to the pressures that go with being HIV positive – and that’s what we want schools to help change.”

All children’s names have been changed