Melinda Gates and Paul Farmer. Marton Perlaki

Paul Farmer and Melinda Gates have a lot in common. They're both Duke University alums, and they're both devoted to improving health around the world, especially in places with few resources. As cochair of the Bill & Melinda Gates Foundation, Gates is particularly dedicated to empowering women and girls, which in turn benefits the health and prosperity of entire communities. Farmer splits his time between Boston (where he runs the Department of Global Health and Social Medicine at Harvard Medical School), Haiti, and Rwanda. He's founding director of Partners in Health, an international nonprofit that delivers health services to the rural and urban poor in a dozen countries. Gates and Farmer don't often work together, but their work certainly unites them. In New York City for UN meetings, the two friends talked to wired about the best ways to improve health all over the world.

WIRED: What innovation do you think is changing the most lives in the developing world?

MELINDA GATES: Human-centered design. Meeting people where they are and really taking their needs and feedback into account. When you let people participate in the design process, you find that they often have ingenious ideas about what would really help them. And it's not a onetime thing; it's an iterative process.

How does that work in practice?

PAUL FARMER: In Haiti I would see people sleeping outside the hospital with their donkey saddle under their neck — they'd been waiting there for days. And no one was asking them, "What are you eating while you're waiting? What is your family eating while you're gone?" We have to design a health delivery system by actually talking to people and asking, "What would make this service better for you?" As soon as you start asking, you get a flood of answers.

GATES: The first time I went to Haiti and saw Paul in 2003, he said, "How can we expect them to take these pills if they have nothing to eat?" He decided that they needed health care workers who could follow patients, and that they had to be people from the community.

FARMER: In Rwanda we worked with the ministry of health when it decided to vaccinate all 13-year-old girls against HPV. And we said, "OK, but what about the girls in school? How would they get the second dose? What about the third? And what about the girls not in school — how do we find them?" With community health workers. And when we studied this new system, we saw that it wasn't just improving the outcomes a little, but a lot: Rates of HPV vaccination in Rwanda are twice what they are in the US.

GATES: Transportation is a huge issue in health. I was in Malawi, and in one village they were mapping things out on a piece of butcher paper, trying to figure out why they don't transport women to facilities to give birth. Well, they realized that they didn't have a bridge to get across a stream that becomes a river during the rainy season. They realized they needed resources to build a bridge — and to buy motorcycles.

Do you see ways for communications technology to help further these efforts?

GATES: I think cell phones are a huge opportunity. I saw it firsthand when I was in India earlier this year. I met with a network of community health workers who had been given cell phones by the government. Each day via cell, the local health authority sends these workers, mostly young women from villages, a list of patients they need to visit. The workers also have training modules they can call into from their phones, and they get free airtime so they can make personal calls to their families once they've listened to their modules. Every week they meet with someone further up in the system who can answer questions. But also, if they go into a patient's home and the person doesn't trust their advice, the worker can call a more highly trained health worker and give the phone to the patient so they can be reassured. What this means is more people are getting better health care in a really efficient way. That's the power of a simple cell phone.

FARMER: The cell phones are also a way to develop human capital. Say you have a 22-year-old woman who becomes a community health worker. Using the example Melinda gave, that person can obtain some continuing education through technology that just 10 years ago wasn't even available.

So in India, do community health workers sign up so they can get a phone?

GATES: Yes. That's part of how they are paid. And they love being more knowledgeable! All of a sudden they have so much more cachet. People say, oh, they really do know what they're talking about. And when I talk about contraceptives, I see that young women are starting to stand up to their husbands, because they're empowered by what they learn from the health workers.

What about established medical professionals?

FARMER: Partners in Health built a teaching hospital in Haiti, and not too long ago I stopped by the emergency room. There had been a road accident with 12 critically injured people, but there were also more than a dozen doctors and nurses, and there was a functioning CAT scanner. Not a single person died. I had never seen that before. I watched a doctor who had always seemed so dispirited. But that night at the new hospital, he looked excited — you can see people come alive if you just give them a chance to learn and to provide better care.