LAURA BARRON-LOPEZ: For more than four decades after leaving the White House, President Jimmy Carter channeled his work on the world stage through his nonprofit Carter Center.

One of the key achievements, the near-eradication of Guinea worm disease, which once affected 3.5 million people.

Last year, there were just 14 cases reported in Africa.

That's why, as William Brangham reports, Carter's work promoting global public health is being remembered by many as a core piece of his legacy.

WILLIAM BRANGHAM: The Carter Center's efforts span more than 80 countries and help bring about the eradication of diseases, the delivery of lifesaving drugs to far-flung areas, and a focus on improving mental health care.

To examine this work that was so important to Jimmy Carter, we are joined again by Dr. Peter Hotez.

He's co-director of the Texas Children's Hospital Center for Vaccine Development and dean of the National School of Tropical Medicine at Baylor College of Medicine.

He worked with Jimmy Carter on neglected tropical diseases.

Dr. Hotez, great to have you back on the program.

When you look at Jimmy Carter's legacy on this front with regards to global public health, what stands out the most to you?

DR. PETER HOTEZ, Baylor College of Medicine: I think, for me, it's the fact that the president really hit home for the world how health is a fundamental human right.

Just like people have a fundamental right to access to food, water, and shelter, they also have a fundamental right of access to being free from ancient scourges, like Guinea-worm, like river blindness, like lymphatic filariasis, diseases that are not household names here in the United States, but globally they're among the most common afflictions of people living in poverty.

He, more than anyone else, I think, really hit on the fact that people have a fundamental right to be free of these parasitic and neglected tropical diseases.

WILLIAM BRANGHAM: And a lot of his work was in the field, but it wasn't only in the field.

I mean, he was also just as active twisting arms of world leaders and pharma executives and business leaders, using the leverage that only a former president can really do.

How important do you think it was to have someone of his stature pointing the finger at these issues?

DR. PETER HOTEZ: Yes, this is what was absolutely game-changing, to have a former president of the United States, arguably the most powerful nation in the world, focus his attention on diseases that represent the most common afflictions of the world's poor.

For me, that was -- for those of us who worked in global health, of course, that was so inspirational, but it really held elected leaders and leaders of foreign countries' feet to the fire, both in terms of low- and middle-income countries, as well as at the advanced countries, high-income countries, to really pay attention to these illnesses.

And there was nothing like the power of the president to provide that kind of advocacy.

WILLIAM BRANGHAM: You have hinted at this already, but do you have a good sense as to why this suddenly became such an important mission in his latter life?

DR. PETER HOTEZ: I think, throughout his presidency and something permeating the president's life, and his wife, Rosalynn, who was a real champion of vaccines as well, was helping, was service, and helping those in need.

And when he asked Dr. Foege, Bill Foege, to head the Carter Center, his original plan, my understanding, was that it was not necessarily around global health, but Dr. Foege convinced the president that this had to be on the forefront as well.

And he quickly got it.

Now we're at a place where more than a billion people annually receive these donated medicines for neglected tropical diseases, and a lot of that is happening through a USAID program that I worked with the president on.

So,imagine, more than a billion people now receive those treatments, and this is an extraordinary legacy of president -- for the president.

WILLIAM BRANGHAM: I want to play a clip from a 2010 story that my colleague Fred de Sam Lazaro did.

He went to South Sudan with Jimmy Carter.

This was on one of their Guinea worm eradication missions there.

And Carter is describing how they wanted to use an insecticide in this pond to kill the Guinea worm eggs and larvae, but the locals there were resistant to it because the pond was very, very precious to them.

Here's how Carter solved that problem.

JIMMY CARTER, Former President of the United States: In fact, the ponds of water were looked upon as sacred.

If that particular rain-filled pond hadn't been there, the village wouldn't have existed.

They wouldn't be alive.

And, of course, we said that the pond was, in effect, sacred, but there was a curse on their pond.

And if they would just help us remove those Guinea worm eggs from their pond or from the drink of water that they took out of that pond, then that curse could be removed from their pond and their village forever.

So, we had, you might say, not only a philosophical, but also a theological explanation to make.

WILLIAM BRANGHAM: How critical is that level of cultural competency for this kind of work?

Because, certainly, a former president of the United States could have come in and said, look, we know how to do this, just let us do it.

But he didn't.

DR. PETER HOTEZ: Yes, this was something also really special about President Carter, and, by the way, the good work of the Carter Center, which still continues today, that it's not all top down.

Yes, of course, President Carter was talking to leaders of low- and middle-income countries, talking to the leadership of the World Health Organization and UNICEF and other international U.N. agencies.

But then he was also talking to the people who were the recipient of these medications and treatments and approaches to ensure that there was community ownership.

And that was really special, because he recognized that, without community ownership, none of these interventions were going to be sustainable.

And that was what was going to allow it to continue.

And that continues to permeate, for instance, the program from our U.S. State Department at USAID for neglected tropical disease control, is to ensure that there is that ownership at the local government level and equally important at the community level, all, again, part of his extraordinary legacy.

WILLIAM BRANGHAM: All right, Dr. Peter Hotez, thank you so much for sharing your remembrances of Jimmy Carter with us.

DR. PETER HOTEZ: Thank you.