WILLIAM BRANGHAM: As the world races to end the HIV/AIDS epidemic, many are looking to South Africa, which has more ground to cover than anywhere else.

They're sending out fleets of bike messengers to deliver lifesaving drugs. They're testing as many people as they can, educating others, running some of the world's top state-of-the-art research labs. They're even trying this, surfing lessons as HIV prevention.

South Africa has more people infected with HIV than any nation on Earth. Over six million people here have the virus. Only half of those are being treated, so South Africa also has one of the greatest challenges.

SALIM ABDOOL KARIM, CAPRISA: One out of every five people living with HIV in the world lives right here in South Africa.

WILLIAM BRANGHAM: Salim Abdool Karim is one of the leaders of South Africa's fight against HIV/AIDS. He runs CAPRISA, a major research lab in Durban.

SALIM ABDOOL KARIM: We estimate that there are about 1,000 new HIV infections in South Africa each day.

WILLIAM BRANGHAM: Every single day?

SALIM ABDOOL KARIM: Every single day. And what's critical in that, it's not just that there's all this HIV, but that young women are a key factor in the highest-incidence populations.

WILLIAM BRANGHAM: This is the Desmond Tutu HIV Foundation Youth Center in Masiphumelele Township in Cape Town. This is the place that uses surfing, among other things, to keep kids engaged in its HIV program.

Here, Linda-Gail Bekker is trying to prevent young women from ever getting HIV in the first place. Some studies indicate that up to 8 percent of teenage girls will become infected every year in parts of South Africa before they reach their mid-20s.

LINDA-GAIL BEKKER, Desmond Tutu HIV Foundation Youth Center: These are unprecedented around the world. We have to do something about this.

WILLIAM BRANGHAM: Bekker's center is trying something few other places in the world are trying. They're offering uninfected teenage girls PrEP. It sands for pre-exposure prophylaxis. And as we have reported in this series, it's a once-a-day pill which greatly lowers your risk of becoming infected if you're exposed to HIV.

WOMAN: You need to take your pill every day so that you can stay protected by the pill.

WILLIAM BRANGHAM: Bekker says, this isn't just crucial HIV prevention for these young women. It's also empowerment. Too often, she says, young girls here have very little say in their own sexual lives and sexual health.

WOMAN: By not taking your pill every day, you might be in risk of getting HIV.

LINDA-GAIL BEKKER: For the first time, we have something that works if people take it, but it works for them. It's in their hands. So, a young woman can swallow a pill a day. She is in control. She decides whether she swallows that pill or not, and she doesn't have to have a conversation with her male partner about what he does and doesn't do under the circumstance.

WILLIAM BRANGHAM: Of course, these innovations come after a very dark history that drove the spread of HIV in South Africa. For years, apartheid era laws created a system where black men were forced to travel long distances from their rural homes to find work, often in the nation's mines.

Many slept with HIV-positive sex workers, and then brought the virus home to different regions. But even after the end of apartheid, and as the HIV epidemic deepened, former President Thabo Mbeki questioned whether HIV even caused AIDS.

THABO MBEKI, Former South African President: How does a virus cause a syndrome?

WILLIAM BRANGHAM: Mbeki was widely criticized for hindering South Africa's response to the epidemic. One study estimates his policies led to the deaths of over 300,000 South Africans.

Mbeki was president when Mpumi Mevana was diagnosed with HIV.

MPUMI MEVANA, HIV Patient: I was diagnosed in the corridor by the doctor in Johannesburg Hospital. "No, my dear, we can't help you in this situation, because you're HIV-positive."

So, I went home that day, thinking that this is the end of the story for me. I'm waiting for the day I'm going to die.

WILLIAM BRANGHAM: This 37-year-old single mother from Soweto is almost completely blind, because of a virus that can strike HIV-positive people who aren't getting treatment.

But in a sign of the times, Mevana is now being treated in one of the most innovative clinics in Johannesburg. The Right to Care clinics treat more people with HIV in South Africa than anyone else. It's 9:30 in the morning, and they have already seen 300 patients so far. They see 12,000 to 15,000 a month.

Ian Sanne is the founding director and CEO.

IAN SANNE, Founding Director and CEO, Right to Care: This clinic happens to be the most efficient clinic in South Africa. It's probably one of the largest.

WILLIAM BRANGHAM: Sanne's goal is to bring the most modern technologies to bear on HIV treatment in South Africa. They have built a robotic pharmacy to speed drug dispensing.

WOMAN: First, you insert your card in there.

WILLIAM BRANGHAM: They have built this prototype ATM-like machine to dispense HIV drugs far away from clinics. They use electronic medical records and bar coding throughout the system.

And wait times in many South African clinics can be more than half-a-day, but here, Sanne says, they average less than an hour. He says, remember, South Africa has over three million people more people who aren't being treated today, so every facility nationwide has to scale up.

IAN SANNE: In my view, we don't have a choice. We actually have to make this work.

DR. AARON MOTSOALEDI, South African Minister of Health: How do we successfully run this world's biggest treatment program?

WILLIAM BRANGHAM: Dr. Aaron Motsoaledi is South Africa's minister of health. He points out that South Africa has made huge gains in recent years.

In 2004, only 400,000 were being treated for HIV. Today, 3.4 million are. In 2004, 70,000 babies a year were born HIV-positive, but treatment has brought that down to less than 6,000 a year. But Motsoaledi says achieving these advances in so short a period of time has stretched the country's resources thin.

DR. AARON MOTSOALEDI: There's no way on earth you could increase the number of doctors proportionately within a decade.

WILLIAM BRANGHAM: So, for now, the burden of South Africa's expanded HIV care falls the hardest on its health care workers.

Nobuhle Ndlela is a nurse in a rural part of KwaZulu-Natal in Eastern South Africa. Her day starts early, getting her girls off to school before she drives to the HIV clinic where she works.

KwaZulu-Natal is one of the most HIV-infected regions on the planet. At the local hospital, people routinely show up with advanced AIDS. They're often also infected with tuberculosis, another epidemic that's plaguing South Africa.

T.B. is the leading cause of death for HIV-positive people here. It's estimated that in many pockets of KwaZulu-Natal, one out of every three adults is infected with HIV.

At the clinic where Ndlela works, she says the stream of patients coming through her door is overwhelming.

NOBUHLE NDLELA, Nurse: Too much. I used to see 260 usually per day. But on the fourth of this month, April, there were 305.

WILLIAM BRANGHAM: Three hundred and five?

NOBUHLE NDLELA: Yes, because…

WILLIAM BRANGHAM: In one day?

NOBUHLE NDLELA: In one day.

So — and it became even difficult for me to observe the patient properly.

WILLIAM BRANGHAM: This woman with her back to us just received her diagnosis a few days ago. She asked that we not show her face or use her name.

She's told us she stares at the sheet of paper with her positive result on it for hours, in disbelief.

WOMAN: I didn't expect it to be like that. I was so shocked and surprised, so disappointed. I don't know how to explain it.

WILLIAM BRANGHAM: She says she was infected by her boyfriend, who didn't know or didn't tell her about his own status. She hasn't yet told her two young sons the news.

Why?

WOMAN: I'm not ready to tell them. Even my family, I never said anything to them. So, it's not easy.

WILLIAM BRANGHAM: What are you worried their reaction is going to be? There's a lot of people in this community that have it. It's — there's no shame in having this disease.

WOMAN: They will think I'm going to die. They will not feel comfortable about it.

WILLIAM BRANGHAM: It obviously doesn't feel this way to her, but she's one of the lucky ones. Consistent HIV medication, which she will now get, can prolong her life for decades. She can still work, still be a mom.

This is the challenge for so much of South Africa today: Find the people who are infected with HIV, but don't know it, persuade them to start treatment, and sustain that treatment for the rest of their lives.

SALIM ABDOOL KARIM: It's not that we don't know what to do. It's a challenge of trying to do what we know works, and to do it at a scale where it can really make a difference.

WILLIAM BRANGHAM: After a long day treating hundreds of HIV patients, Nobuhle Ndlela is tired, but not defeated.

NOBUHLE NDLELA: God knows every step I take.

WILLIAM BRANGHAM: She has a few hours with her daughters to pray and to sing and to rest, before she starts again, wrestling against an epidemic.

For the "PBS NewsHour," I'm William Brangham in KwaZulu-Natal, South Africa.