Nurith Aizenman

World leaders have celebrated Earth Day today by gathering in New York to sign a historic climate agreement to reduce greenhouse gas emissions. But some of the most vital environmental work is being done by ordinary citizens with extraordinary courage. People like subsistence farmers and tribal leaders in the poorest countries are standing up to some of the world's most powerful industries. And a growing number of them have been attacked — and sometimes murdered — for trying to protect the environment.

It was a hospital — but to psychologist Inka Weissbecker it looked more like a prison. She had come to South Sudan to check out the country's only health facility for treating patients with mental illness.

"There was a hallway leading past these cells with bars on them," she recalls. "Behind one set of bars I saw a mattress covered in plastic. And on it was urine and feces — and this woman lying with her face to the wall. I don't know if she was dead or just sleeping. Nobody seemed to care."

Editor's note: Sir Fazle Hasan Abed is the award-winning founder of one of the largest nongovernmental aid groups in the world. It's called BRAC, and it operates in 11 countries across Africa and Asia. On Friday Abed's colleagues at BRAC announced that he has died. He was 84 and was being treated for a brain tumor. In 2016 NPR interviewed Abed. In his memory we are re-posting that story.

Critics call them "parachute researchers": Scientists from wealthy nations who swoop in when a puzzling disease breaks out in a developing country. They collect specimens, then head straight back home to analyze them. They don't coordinate with people fighting the epidemic on the ground — don't even share their discoveries for months, if ever.

Sometimes it's because they want to publish their results – and medical journals prefer exclusives. And sometimes it's because they can make a lot of money by coming up with copyrighted treatments for the disease.

The boys and girls at the party are matched up by height. They dance together. Maybe they do a little grinding. They talk about love ... and marriage. Then they eat birthday cake.

That doesn't sound like a radical event. But in a predominantly conservative Muslim slum in the Indian city of Kolkata it was unheard of. And what made it happen? Lush, romantic Bollywood movies.

That's what Kabita Chakraborty learned after she began doing research in Kolkata.

The world is in danger of running out of vaccines for a deadly disease: yellow fever. A major outbreak in the African nation of Angola has already depleted the stockpile that world health officials had set aside for emergencies. It's unclear whether new vaccines can be made in time — even as officials worry that the epidemic could spread through Asia and beyond.

They're simply test tubes, mainly filled with blood and saliva, but to researcher Beatriz Parra Patino, they're a lot more.

To her, each tube represents "a human being." And the blood and saliva may hold the answer to one of the many mysteries about the Zika virus sweeping through her native Colombia: Is it linked to Guillan-Barre syndrome, a neurological condition with excruciating effects, including temporary paralysis.

"I treat the tubes as if I was treating the person," she says, "with respect and trying to do my best."

Keila Atuesta Jaimes, a petite 25-year-old, is lying on an exam table next to an ultrasound machine. The doctor moves the wand across her belly. It's pretty flat. She's only about three months pregnant. Then suddenly, there's the heartbeat!

Atuesta smiles. Nervously. About three weeks ago she came down with the kind of rash and fever she figured could mean only one thing: Zika.

The Zika outbreak is aggravating an already tense relationship between Venezuela and Colombia. In Colombia, more than 37,000 people have fallen sick. Venezuela reports fewer than 5,000 cases — a number that Colombian officials find suspiciously low.

Juan Bitar heads the health department of a state in Colombia that shares a long border with Venezuela. "A lot of people who are sick with Zika in Venezuela are coming [to Colombia] for medical attention," he says.

Two weeks ago, Jenny Tolosa found out she was pregnant.

The 23-year-old had no idea. "I didn't have any symptoms," she says. "I totally didn't expect this." She giggles, because she was excited by the news.

But she was also worried. She says her first thought was, "I think I had Zika last December!"

That's the mosquito-borne virus that's spreading through Latin America — and has been linked to the birth defect microcephaly, which causes an abnormally small head and possible brain damage.

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