Just over four years ago, on July 17, 2014, six delegates on their way to the International AIDS Conference died in the shoot-down of Malaysia Airlines Flight 17 over eastern Ukraine.

The delegates were among the 298 people killed hours after their flight took off from Amsterdam.

International investigations concluded that the missile that downed the jet originated with the Russian military, which has denied involvement.

This year, Amsterdam is where thousands of experts in public health and global development are gathering for the International AIDS Conference, which begins on Monday.

"I'm hopeful that people will still remember them," Owen Ryan, the outgoing executive director of the International AIDS Society, says of the colleagues he lost in the AIDS prevention research and activism community that day.

Ryan told NPR's Korva Coleman he wants their legacy to help draw attention to AIDS as a continuing crisis, "and know it's important we keep this fight going."

About 37 million people around the world were living with HIV/AIDS in 2017, according to the World Health Organization. The group says 940,000 people died of HIV-related diseases last year.

On the eve of the 22nd International AIDS Conference, Ryan talked with NPR about the current state of the AIDS crisis around the world and why it's important to keep funding AIDS prevention efforts.

Interview Highlights

OnJoep Lange,a former president of the International AIDS Society who died on MH17

It's hard to describe in short ways all the ways that Joep had kind of really transformed the HIV movement. One very large way though was how he made the world wake up to the need for antiretroviral treatment in Africa. He was one of the first researchers, scientists, activists who was forcing donor governments to face the problems that were in Africa — and to get rid of the impediments that were keeping people away from lifesaving treatment.

He is in large part to thank for many of the millions of people who are on treatment today.

On what can slow down the rate of current AIDS infections

Honestly, what needs to be done is this sense of complacency that has settled on many of us. There's really this feeling in many parts of the world that AIDS is over, and that is really far from true.

It's one of the reasons we miss Joep the most right now — he had an unbelievable ability to speak truth to power, regardless of who he's speaking to. He just knew how to go right to them and say, "What you believe is not true and we need more money for this."

On the development of drugs to stop AIDS

For one of the first times, we're doing a large-scale clinical trial for vaccines in South Africa. And South Africa's one of those countries where if we can get it right there, we can get it right in a lot of places around the world.

But until we get more people on treatment in the short term, we're going to keep trying to play catch-up. So we're really hoping we can do both things at the same time: get people on treatment, and then longer-term prevention options.

On particular regions where the AIDS crisis is growing

Eastern Europe and Central Asia is a big focus of this conference. You've seen that over time as economies have improved, donors have walked away. And with them walking away has walked away political will.

So in many places, and this also includes Russia, you've seen the epidemic come back with force. And you're seeing in urban centers and rural areas people who are just completely away from treatment and this massive explosion in new infections and I think people just don't realize it.

On preventing future epidemics

We always have to be aware and it's the exact moment you take your finger off the pulse of epidemiology that you start to see problems occur. We need to fund the systems that keep us vigilant against the next great disease that's coming — 'cause we know it'll happen.

We've seen this with Ebola, we've seen this with SARS in the past. We need to keep things like the CDC and WHO — we need to keep them vibrant and strong and paying attention to all of this.

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