JOHANNESBURG (REUTERS) - Before 20-year-old Lebogang Motsumi even had sex with her first "blesser" - or sugar daddy - a successful, married, company boss more than twice her age, he handed her a wad of cash.

He was soon making regular deposits into her bank account, paying her rent and taking her out in exchange for sex, which the young single mother readily accepted as she had a three-month-old baby to feed.

"It's a confidence boost at the time but when you're alone and you're thinking about this, you feel very disgusted. This man is old enough to be your dad," she told the Thomson Reuters Foundation.

"I would bathe and I would really scrub myself because I just wanted whatever smell to get out of my body."

Experts are grappling for ways to reduce relationships like these, which are fuelling new HIV infections in South Africa, home to 7 million HIV positive people - the highest number in the world, according to the UN agency for HIV/AIDS (UNAIDS).

But "blessing" - where wealthy, older men spend lavishly on younger women - has become a symbol of prestige for teenage girls trapped in a toxic cycle of poverty and ignorance, amid record unemployment and stark inequalities in South Africa.

The term emerged when girls and women started tagging #blessed on Instagram and Facebook posts, showing their expensive clothes and shoes paid for by men dubbed blessers.

"There is actually a group of women who are happy to be called 'blessees', who own it, who are at the mercy of this person that can provide them with money for as long as they're willing to comply," said Mr Karabo Sitto, a Johannesburg academic.

More than 10 per cent of young women in South Africa are HIV positive, compared to 4 per cent of young men, UNAIDS says.

"Women often do not have the power to negotiate safe sex in these relationships, especially as some men offer more money for sex without a condom," said Ms Nozizwe Madlala-Routledge, head of Embrace Dignity, a charity that supports women who sell sex.

Although new HIV infections have fallen, almost 40 per cent of the 270,000 people infected in 2016 were young women aged between 15 and 24, South Africa said last year, amid a push to roll out pre-exposure prophylaxis (PrEP) to at risk adolescents.

As the daily medication almost eradicates the risk of infection, South Africa is one of several countries on the continent conducting trials to assess how it could help protect people who have difficulty negotiating condom use.

About a third of teenage girls in South Africa have had a partner at least five years older than them, a 2012 government survey found.

"Reducing age-disparate sex is key to slowing HIV rates in young women," said Mr Salim Abdool Karim, director of the Centre for the AIDS Programme of Research in South Africa, a partnership between five research institutions.

But South Africa's youth population is booming, along with poverty and unemployment rates, increasing the vulnerability of adolescent girls, who are already disadvantaged by high levels of violence, rape and harmful traditions like child marriage.

"Money is always a factor in relationships," said a Facebook page for blessing. "This is just an upfront and honest way of dating for our modern times."

South Africa launched the She Conquers campaign in 2016 to decrease new HIV infections, pregnancies and violence towards young women and girls and help them stay in school.

"Government can promote programmes that relate to gender equity and to empower women," said Mr Foster Mohale, a Health Ministry spokesman.

"But ultimately, society needs to respond to social and moral issues."

Some are calling for greater efforts to reach out to blessers, often married men with multiple sexual partners.

"These men are driving HIV transmission, and compounding an already massive public healthcare problem," Ms Hermina Manjekana Dyeshana, a health expert with Right to Care, a local HIV charity, said in a statement.

"Very few know their HIV status and many opt not to be tested at all. Those who are recently infected with HIV have extremely high viral loads. Tragically, they are not entering the health system to get support or treatment."

In Ms Motsumi's case, it was a blesser who persuaded her to stop having transactional sex. After he gave her a lecture over breakfast, she deleted all her sugar daddies' numbers, changed hers, and gave away everything they had bought her.

"He just started telling me how smart I am and how I could go far in life and how he would never marry someone like me because of my values and morals," she said.

"He gave me a lot of money and he was like, 'this is the last time I'm seeing you. Go do something useful'."

Today Ms Motsumi, who is HIV positive, gives talks to other young people about the disease.

"It was difficult because I was used to always being able to call someone and I've got money. But I was determined to be the change that I want to see," she said.