Kwazulu Natal countryside
Kwazulu Natal, in eastern South Africa, has high rates of HIV infectionMarco Longari/AFP/Getty Images

Sanelisiwe Nkomo is 22 and has three children. She is from Kwazulu-Natal, a province which stretches along South Africa's eastern coast, which is the epicentre of the country's HIV epidemic. She tested positive for HIV last year.

"Me and boyfriend at the time had unprotected sex and unfortunately both of us didn't know our HIV status and we hadn't been tested," Nkomo says. "So last year when I got pregnant, I went in for antenatal care classes and they asked me to do a HIV test. Then when the result came back positive."

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South Africa has one of the highest rates of HIV in the world, with an estimated seven million people living with the virus in 2015. Young women are the face of the epidemic, with around 7,500 women aged 15 to 24 infected with HIV every week last year. More than 90% of the adolescents infected in sub-Saharan Africa are girls.

In Kwazulu-Natal, HIV prevalence is around 40% – compared to 18% in the Northern Cape and Western Cape.

Nkomo was terrified when she received her diagnosis, not just for her own health, but for her children's. More than 400 babies are infected with HIV globally every day – of which around 75% live in sub-Saharan Africa. The majority acquire HIV from their mothers during pregnancy, childbirth and breastfeeding.

Although medical interventions can keep both mothers and babies healthy, understaffed hospitals and stigma often prevents women from seeking life-saving, antiretroviral therapy. Without medical support, up to 40% of children born to HIV-positive mothers will contract the virus. With medical intervention, the figure is reduced to 2%.

But at the antenatal clinic, Nkomo was introduced to mothers2mothers, an Africa-based NGO which trains and employs local mothers living with HIV – which provides education and support to other women, to protect their children from infection. Nkomo met Jean, a mothers2mothers "mentor mother".

HIV in South Africa
Sanesiliwe Nkomo is a peer mentor for the NGO mothers2mothersmothers2mothers

"When I found out I was HIV positive I was really devastated, I was shocked, but luckily for me I had a mentor mother called Jean – she was amazing in supporting me, because I was really worried how I would break the news to my family and to my partner," Nkomo says.

"The information she gave me really put my mind at ease because I was worried about how on earth a HIV positive mother could give birth to a HIV negative child."

Mothers2mothers also employs local women to help promote safe sex and tackle stigma – something Nkomo experienced as first-hand when she found out she was HIV positive.

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"With my family, I really had a lot of support from them – knowing that my sister was also HIV positive," she says. "But in terms of the community, and my friends at the time, it was really difficult, because when some of heard I was HIV positive it was like they couldn't relate to me any more, they wouldn't really be comfortable being around me."

Young women are at particular risk of contracting HIV – in part, because of their low status in a strongly patriarchal society. In poorer areas, women are vulnerable to older men who lure them with gifts and money in exchange for sex.

Emma France, the European director for mothers2mothers, says there are a variety of reasons why young women are vulnerable to contracting HIV in sub-Saharan Africa. "Reasons of lack of knowledge, lack of knowledge about HIV, lack of knowledge about how it is contracted, gender inequality, girls essentially not being in relationships in which they have equal power to insist that contraception is used, lack of access to education."

"Often the girls are child brides, they are married early, we are even seeing girls presenting with HIV, who are pregnant at 12 or 13."

Thanks to mothers2mothers, Nkomo received support and medical intervention to ensure her and her children will lead long and healthy lives. And earlier this year, she joined the charity as a peer mentor, to educate, inform and relate to other young mothers. She now works in the township of Umlazi, doing housecalls, running youth groups and support groups in hospitals and clinics.

HIV in South Africa
Nkomo works with young mothers in the Kwazulu-Natal provincemothers2mothers

Nkomo reaches out to women and young people to help them understand HIV and infection prevention and to make sure those who are HIV positive receive the right support. In doing so, she is helping tackle stigma. Nkomo also has a career and earns an income, so she can support her family.

"I teach them if you have started being sexually active, use protection, so you won't be faced with an early pregnancy or be infected with HIV. That's what I tell them first. Then I teach them to know their worth as a woman. I tell them if you don't know your worth, you let other people define it for you.

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"The information about HIV positive women being able to give birth to HIV negative children is still information that I find people don't know about - but mothers2mothers they give out that information to people, and it is information that people really need to know."

So far, mothers2mothers has reached 1.5 million HIV positive women across seven countries in sub-Saharan Africa, achieving virtual elimination of HIV transmitted from mother-to-child in the women they have provided care to.

"The power of the model has very much been recognising that local women have the power, they are the solution to this great pandemic," France says. "We train, empower and employ - so we pay local women to support other local women and meet their needs, provide them with life-saving support and information around HIV, around their sexual and reproductive health."

World Aids Day is marked on 1 December.

HIV in South Africa
Nkomo meets a young mother at her homemothers2mothers