Losing years of progress against HIV, and farming plastic on Mars
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This is a science podcast for July 3rd, 2025. I'm Sarah Crespi. First this week, USAID helped two African countries rein in HIV. Then came President Donald Trump. Senior news correspondent John Cohen talks with producer Kevin MacLean about how treatment and prevention cutbacks are hitting pregnant people, children and teens especially hard.

Next on the show, I talk with researcher Robin Wordsworth about life on Mars, cultivating it, that is. More specifically, we talk about the challenges and possibilities of using microbes to grow plastics, drugs, and food on the surface of the red planet or other bodies in the solar system.

In January of this year, the Trump administration started a widespread effort to slash government programs and spending. One of the major targets was the U.S. Agency for International Development, or USAID, one of the country's main administrators of foreign aid. In a series supported by the Pulitzer Center, the News from Science team is looking into the impacts of U.S. funding cuts on global health.

Today, we have John Cohen, who traveled to Lesotho and Eswatini to report on how the loss of aid is affecting treatment and prevention of HIV and AIDS. Hi, John. Welcome back to the Science Podcast. Thanks for having me. Glad to have you.

Lesotho and Eswatini, why were these the places that you decided to travel for this series? They're small countries. They have populations of one to two million people, but they have the highest HIV prevalence of any countries in the world, which means more adults are living with HIV there than anywhere else. On

On top of that, with support from the U.S. government, in particular from the PEPFAR program, they've had the most remarkable success in turning around their epidemics over the past 20 years. So they both seemed particularly vulnerable to me. How does foreign aid play a role in curbing the epidemic in these places? So turn the clock back to 2003 when PEPFAR is formed by President George W. Bush.

Anti-retroviral drugs are saving the lives of people living with HIV, everyone who can access them. But most people in the world live in countries that can't access them. The drugs are too expensive. Kepfar comes in, and there's also the creation of the Global Fund. And those two forces make the drug prices plummet through generic manufacturers and make delivery and access possible. So everywhere in the world,

people living with HIV can access treatments that keep them alive. And on top of that, if you take the treatment regularly, your viral level goes down so low that you don't transmit to others. So you break the back of the epidemic. Can you talk a little bit more about how the HIV AIDS epidemic is sort of impacting populations there? Several people said to me in both countries that had PEPFAR and the

and the Global Fund not kicked in when they did, these countries might have been wiped off the map. When you get to about 50 years of age in either country, half the people are infected. Half the people are living with HIV. It turns out with good treatment,

It's a chronic disease that you can live with. It's not a death sentence. But turn back the clock to 2003. If you showed up at a clinic and were found to have HIV, it was usually because you already were sick. That's why you went to the clinic. And you might have had a few years to live when you got your diagnosis. And people were afraid to go get diagnosed because there were no treatments available. So why am I going to go get that? Rather not know was the attitude in a lot of places. All

All of that changed. And the stigma and discrimination that went along with being identified as somebody who had HIV, it just went away. It still exists, but it's nothing what it was. Can you talk a little bit more about the sort of dramatic progress that has happened? The United Nations Joint Program on HIV AIDS set these targets of

By the year 2030, let's shoot for having 95% of people who are living with HIV get tested and know their status. Let's shoot for 95% of those people getting on treatment and 95% of those people who are on treatment completely suppressing their virus so that they're undetectable on standard tests. So it's called 95-95-95. Both Lesotho and Eswatini have hit that target already.

When you hear what the target is, it sounds so ambitious. It was really amazing just to hear that they hit and what exceeded it even. Yeah, and most countries in the world have not. Progress is remarkable.

And both countries are deeply grateful to the United States. And it owes a great debt to the United States for helping them build their health care systems so that they can not only have access to the medicines, but deliver them with qualified people who then monitor their blood to make sure their virus is suppressed, who help them get to the clinic if they need transport. These are the critical things that make it work.

And on top of that, they've done very aggressive prevention programs, including using these same drugs, some of these same drugs, in people who are not infected to protect them. In the same way you might take malaria medicine before going to a malaria region, you can take an anti-HAV drug before having sex in a high-risk situation. It works. It's called PrEP. And male circumcision done voluntarily by adults, it works.

And they have promoted these aggressively within PEPFAR countries, which are more than 50 countries in the world. And they've had dramatic success. These are the types of programs that are now losing the funding that had previously been going? Yeah. USAID is about 60 percent of the PEPFAR funding. The U.S. CDC and the Department of Defense make up the other 40 percent.

But USAID is the backbone of PEPFAR. If you pull USAID funding, like in East Huatini, it might mean that you're pulling all transport away. So taking samples from a clinic to a central laboratory can't be done. So then you can't monitor people. And it also is about collecting data so you can make policy decisions.

That's critical to the response here. If you know where you're failing, you can address that. And what are folks in both countries thinking in terms of how to set their next goal, their next plan of action? The first thing is to try to stop the dam from bursting.

And I walked into clinics in Lesotho. I walked into a clinic with, I don't know, maybe a dozen pregnant women waiting to be seen. They had no HIV tests there for the women, none. And they had no tests for their babies. Preventing mother to child transmission of HIV is the easiest. It's the lowest hanging fruit. If you put a pregnant woman who's living with HIV on antiretroviral treatment and she takes her drugs, she's not going to transmit to her baby. The risk just

plummets and breastfeeding also transmits. If she stays on treatment during breastfeeding, she's not going to transmit.

If you don't offer treatment to pregnant women who are living with HIV, about 30% will transmit through birth or breastfeeding. So that's where they're at. The clock has been turned back to 2003. So number one, how do you fill that gap? Because that's such an obvious need. And a big problem isn't simply having the test, it's having treatment.

staff who are paid to administer it and counsel people who take the test. Those staff have been cut. Governments in places like Eswatini and Lesotho, they're aware of the fact that they have to pay their own way and that they've been relying too much on foreign assistance. But the hope was that they would spend the next five years phasing out this funding and taking it over the

the programs with their own people styled to fit their budgets. That all went poof. Yeah, they had set goals that were meant to target 2030. And when you pull things away five years in advance, it really screws up the whole plan, right? The head of the UNAIDS program in East Swatini said to me, it's like having a patient on a life support machine and just walking in and pulling the plug. You know, I met a

A teenager in East Latina who lives in the rural part of the country, it's hard for him to get from his home to the clinic. There was a program that took teenagers once a month to the clinic.

get their meds, sit in a kind of group with other people living with HIV, talk about your challenges, gave them a meal and took them back home, tested their viral load, counted their pills to make sure they were taking their medication. Well, the program stopped and he just stopped taking his medication. Is it his responsibility to take care of himself? Of

I've raised three teenagers. They need our guidance. They need our help so that you can push them out of the nest and they fly and don't just fall to the ground. This guy's just fallen to the ground. You know, he knows better. He's intelligent, but he's a teenager. You want

One of the things in reading through your story that is so noticeable is some of the portraits of so many different people that you spoke to, that you encountered. Were there other folks that you wanted to touch on? I want to stress something, too. This was a collaboration with a local photographer, Oupa Nkosi, who's from South Africa, but his parents are from these countries. He speaks the languages.

And we really worked together as a team doing these interviews. I do not just show up in a rural village and go, hi, I'm here. And the fact that he was culturally aware of how to introduce us made an enormous difference. And he was really, really terrific to work with.

We met a doctor who works in Lesotho and helps run a mobile clinic program at factories. The country has a huge textile industry. And in these factories, largely operated by women, prevalence rates are above 40%. They have a clinic right outside at lunchtime. You can just walk into a mobile van, see a doctor, get your medication, get a blood test. It's just awesome.

obviously a smart way to handle a really difficult problem. And this doctor, her name was Blakove, just beside herself with how can we stop doing this? It's working. What am I supposed to do? I know how to do this. We've set it up properly. And now it's all just going to be taken away. You won't see people developing AIDS and dying from AIDS quickly. It takes time.

But you will see it in babies. You will see it in young children because they develop disease far more quickly. And I predict in the next six months, if this isn't turned around somehow, it will be a catastrophe in these countries. Is there any hope right now in terms of finding different sources? Is there anything on the horizon? These countries each receive about $70 million a year for

from the U.S. government to support their HIV AIDS programs. Their health budgets for everything are like $170 million. So how much can they support themselves? I don't know. They certainly can't support $70 million. There is an increased support coming from some philanthropies

The Gates Foundation has said it wants to step up its philanthropic efforts. We're seeing aid cut back also in Europe from European donors. So it's a really troubling time. I think countries are also going to have to look at what PEPFAR was doing and ask, can we really afford to do it this way? I think that everyone is...

is still in one of these stages of grief in these countries where they've gotten past the denial and past the anger. They're at the stage of grief that isn't listed in the normal list, and it's called baffled. They're just baffled. They have this look on their face. You see it again and again of, what am I going to do? Zooming out a little bit more broadly about the global health series overall, what's

What were you and the rest of the team aiming to achieve? What did you want the audience to understand about what the loss of U.S. funding means for global health? We chose to focus on children and teens. And Martin Ensorink is going to Guinea to look at malaria, and Catherine Offord went to Nepal to look at nutrition. We want people

especially people in the United States, to see the good that has occurred and to document the dilemmas that now exist by cutting these programs.

Everyone everywhere cares about babies, children. We wanted to focus on those groups because they're extra vulnerable. They get hurt sooner. They suffer more quickly than adults. We hope that by showing this, there will be a serious look at what many call the greatest foreign aid program the U.S. has ever endeavored upon, which is BEPFAR.

and to look at the future with clearer eyes about what the United States is choosing to do when it is celebrated widely around the world for a program that has saved an estimated 26 million lives. And then why take a chainsaw to it, as Elon Musk said? Why throw it into the wood chipper, as he said? We want to show by introducing you to real people who both provide care and

and receive care, what's happening? The thing that sort of popped into my head when I saw the story that you were reporting is, you know, not too long ago, we were talking to you about Lenacapivir, which was the 2024 breakthrough of the year and its potential as a PrEP injectable to offer the six months of protection.

against HIV infection. And you were talking back then about how they are planning this much more equitable rollout of the drug. Has any of that process been disrupted at all? Completely. So lenacapavir is an anti-HIV drug that is on the market as a treatment.

But it proved in two very large clinical trials that it works remarkably well as an injection to prevent infection in people who are not infected. Both PEPFAR and the Global Fund together committed to rolling out injectable lenacapavir to resource-limited countries over the next three years to 2 million people.

What has happened in the past with anti-HIV progress is it rolls out slowly to poorer countries. And they really wanted to get ahead of this, along with Gilead, the manufacturer of the drug, to make it accessible through generic companies the moment it gets approval. Well, that's all now got a giant question mark over it. The Global Fund says that it still will try to support this.

But PEPFAR made it pretty clear in documents that it doesn't want to support pre-exposure prophylaxis. Without PEPFAR, it's unclear what the Global Fund can do. And PEPFAR also supports the Global Fund. And in the current budget that President Trump has put forward, they're cutting out all funding to the Global Fund.

So who knows? I don't know what's going to happen. You've covered this area for so long. I mean, how have you felt watching this whole process unfold with the loss of aid? I started covering HIV AIDS at a time when there were no good medicines. I started covering it full time in 1990 as my main beat. I have walked into hospitals that look like warehouses of hundreds of people dying from AIDS. I have seen large

what looked like, you know, the great influenza photos that you see of people just on cots all over this enormous space dying. I've witnessed really horrific things that hit me really hard. That all ended because of the availability of these drugs. I don't see that any longer anywhere. To think that we're going to slip and go backward, it's heartbreaking. And everyone who is

is at the front who has been doing this as long as I have. The people who are giving the care are far more connected to the people. They are in a state of disbelief. You know, really? That's what we're facing now? Of going back to seeing a six-month-old baby dying from AIDS?

And that is going to happen unless something changes soon. We're going to see horrific things that I witnessed 25 years ago becoming commonplace. Well, thank you so much, John. Been my pleasure. John Cohen is a senior correspondent for Science. You can find a link to this story and the rest of the series on foreign aid impacts at science.org slash podcasts. Next up, the challenges of staying alive on the red planet.

Let's take human space travel to other planets for granted, just for a second, and assume we have people going to Mars and going to set up some kind of temporary or permanent habitation. What would that be made of? Can it be the ship that we send the people on? If that were true, how would they get it back to Earth?

How will we get walls and doors to Mars, though? Some say mine the planet, process that. But what about growing things using bioreactors?

This week in Science Advances, Robin Wordsworth wrote about making stuff on Mars or maybe potentially other planets with little algae. Hi, Robin. Welcome to the Science Podcast. Hi. Thanks. It's great to be here. Yeah. So why are we crossing off mining the local environment for materials if we went to Mars and wanted to make things? Why not just use Mars dust and Mars rocks?

Well, I wouldn't say we're crossing it off necessarily, but it's just that there's a real opportunity to think about how biology can contribute to sustaining life elsewhere. And part of the motivation for this is that we know actually that our technological civilization on Earth depends on the biosphere. It's emerged from it and depends on it. And so when we think about life on other worlds, to us, it felt natural to consider how biology itself could enable generating habitable conditions. Yeah.

Yeah, it's really good at organizing materials and not necessarily destroying them for future use, but making things recyclable and sustainable and perhaps long-term habitable. But if we go to Mars, we are going to need a lot of stuff there. And a lot of it will actually be built to protect us from the harsh environment of that planet.

I think first of like how much oxygen there isn't, for example. What are some of the toughest aspects of being on Mars and making stuff there, particularly if you want to do it with biological agents, with little organisms? Mars in some ways is the most benign environment beyond Earth. Oh, come on. It's tough in the solar system, right? I mean, everywhere beyond Earth, it's

not habitable to Earth-like life in the way we understand it, with exceptions of maybe the deep interiors of icy moons and so on. But so the Martian surface has

There's an atmosphere. It's about 600 pascals of CO2, which is for references, less than 1% of Earth's atmospheric pressure. So we don't have that on Earth. Not even the tallest mountain will get you that. It's good because you have a source of CO2, which is something that life, biology, plants need, but it's not enough critically to stabilize liquid water. And so if you had a ball of water and you placed it on the surface of Mars, it would simultaneously start boiling and probably freezing. And you just wouldn't be able to sustain it there long term. And on

on top of that there's

quite an intense amount of radiation and the temperatures usually drop well below what we're used to on Earth, except maybe the wintertime in Antarctica. And so it's a challenging environment for sure. Oh, and we can't forget about the weird toxic chemicals kind of littering the surface. There's the perchlorates as well. Yeah, they're an additional challenge and that's a little bit unique to Mars. You don't see them in the same way in other places. So lots of challenges, but compared to some other places in the solar system, still pretty good. Sounds great. Okay.

Okay, let's go. It is kind of intimidating when you think about maintaining life there because so many of these conditions like have made us the Goldilocks planet, right? We have room temperature, water as a liquid, for example. We're not constantly bombarded with ionizing radiation. Like we just, we have a lot going for us. But you're looking to see who could grow on Mars and what they could grow, basically. What kind of bioproducts were you thinking about making?

if you were to try this on another planet? The concept is pretty general. We were really focused on how do you create something using biomaterials which enables life, simple life like algae or plants to grow. And the idea is once you can do that, if you could scale things, then you could produce a diverse range of biomaterials that we would want for a lot of different contexts. And so for humans, food is an obvious one, pharmaceuticals potentially, even chemicals

building materials. We use biology for really all sorts of things on Earth. And so once you can get to the point where you can, in a scalable way, create biomass, you can do a lot with it. And so we were focused on the problem of how, if you like, biology can enable conditions for its own sustenance on another planet. You have to grow things and you have to protect them from Mars. I looked into this a little bit and there are these like

Earth environments used as Mars mimics, but they're super remote and intense, like volcanoes in Antarctica intense, and they still don't even get you halfway there. So what did you do to kind of set up a Mars analog to test this out in? So

So field sites are very useful and informative, but they cannot get you all the way to Mars because of what we were just talking about with pressure and other factors. So we used a Mars chamber, which means in practice, we had a vacuum chamber in our lab that we brought down to 600 Pascal pressure. There was a CO2 inlet. So we replaced our nitrogen oxygen atmosphere with carbon dioxide. So that brings you to conditions where without

anything else, you wouldn't be able to sustain water. And so that was the chamber that we did our experiments in. And we had to create something that could sustain life inside it. So that's where the bioplastics came in. You were going to see if bioplastics could kind of stand up to this harsh environment so that you can kind of, I guess, you're kind of stepwise making your way into growing things on there. So how did that work out?

As a specific bioplastic, we use something called PLA, which is one of the most common bioplastics out there. And we really just wanted to test the proposition that materials generated by life could be used to sustain life in another environment. And it turned out that we had to do a few things like seal the chamber correctly and 3D print it in the right way. But it absolutely worked. It got liquid inside the chamber, liquid water to be stable. And it turned out we were able to grow algae in there.

It took a few trials and a bit of iteration, but it started working pretty robustly. You're able to grow algae in this bioplastic. And you're not genetically engineering this algae to like tolerate anything. You're just saying, well, if we give the pressure, we give this is barely habitable environment. You can grow algae, basically. No, that's right. And there certainly is an avenue you could take where you try to do that. But our intention was to start with a common type of algae and grow it. Try to keep it happy under humidity.

pretty earth-like conditions. The pressure inside the chamber was still lower than on earth, but it was high enough for liquid water, which was really the key thing. It's kind of a loop here. So you can grow the algae in there. And then if you can show that, then you can maybe get an organism to make the PLA, the plastic that the thing is made of. And then you're kind of in business, right? So you're

stepping your way across to making a habitat for both people and the organisms we need to help us make food and drugs and buildings. Absolutely. Yeah, that's the idea. So the bioplastic PLA specifically, the process is you get something produced from algae, sugars or carbohydrates, and then a type of bacteria converts that to lactic acid. And then you can combine the lactic acid into a polymer. And so that then

demonstrates there's a route from growing a bunch of algae to creating more chambers. And so in principle, it's very possible to scale it. And were you worried about radiation or perchlorates in this setting, or is it mostly just getting water to behave itself? Getting water to behave itself was the first step for sure. And so certainly you've got to worry about other things as well. Radiation is a big deal for humans. I would say it's less of a big deal for plants. They're pretty good generally at surviving higher radiation levels. The perchlorates

The perchlorates, you've got to be a bit more careful with those. Plants don't like perchlorates. And so there's different things you could do to approach that. Maybe leaching them out of the soil or chemically altering them. And some other groups have looked at types of plant strains that would be more robust to survive them. But the radiation is not so much of a concern.

Some of what you've talked about, like getting the algae to make the carbon stuff that the bacteria convert to things we can turn into plastic, that's been scaled on Earth, right? How come we're not making stuff like this on Earth? Does the finances only really work out if you're all the way over at Mars for this kind of process to supply you with what you need? I mean, first of all, we are doing this. The bioplastics industry is big on Earth and growing yearly. We're not doing it as much because we have this

huge supply of organics from under the ground that plants have made over millions of years. That's a very circular way of saying petroleum. Right. Oil supplies are ultimately from the biosphere, but they're not renewable in the way that bioplastics are. This whole area of investigation, part of the reason we're so interested in it is that it

also links into questions about sustainability here on Earth. And so in the future, our hope would be as the science for this develops, there would be spinoff applications for thinking about bioplastics here on Earth as well. So right now it sounds like go to Mars, all you need is a pocket full of algae and a 3D printer. More or less, yeah. We're still working on what the full closed loop system would be like. That's the essential idea. So one thing we should probably touch on is that Mars's temperature is also higher

Pretty cold for life. That's one thing that we didn't cover tons in this study. We actually looked at that a few years ago, how you would overcome it. I mean, I always like analogies for temperature. And if you're talking about Mars specifically, conditions in Antarctica, especially in wintertime, those are sort of same kind of range as you expect for mid-latitudes on Mars. If you want to elevate that, especially if you want to do it through something that biology can generate, you have a few options. And we think aerogels are something that could be used for this.

materials which are ultralight and they pass a lot of sunlight, but they block infrared radiation. And so it's a potential route to stabilizing temperature by many tens of degrees Kelvin or Celsius. It does really make me wonder on Earth, we have such a luxury of all this stuff around us that's turning sunlight off.

into energy that we can use. Like that just like fundamental productivity that powers everything. Going somewhere without that for a long time just seems nuts. Yeah. Now that I'm reading this paper, you know.

The International Space Station, I guess, is doing okay. Well, it's interesting because we see it as this luxury, but really that's partly because we've evolved to fit it. If you start to expand beyond that and consider other environments, other ways of operating, it expands how you think about life elsewhere. And so we do see this as having...

in the long run, fundamental implications for thinking about astrobiology as well. All right. Thanks, Robin. This has been really interesting. Thanks a lot. It's been great to chat. Robin Wordsworth is the Gordon McKay Professor in the School of Engineering and Applied Sciences at Harvard University. You can find a link to the advances paper we talked about at science.org slash podcast.

And that concludes this edition of the Science Podcast. If you have any comments or suggestions for the show, write to us at sciencepodcasts at aaaas.org. To find us on podcasting apps, search for Science Magazine. Or you can listen on our website, science.org slash podcast. This

This show was edited by me, Sarah Crespi, Megan Cantwell, and Kevin McLean. We had production help from Podigy. Our music is by Jeffrey Cook and Wenkoy Wen. On behalf of Science and its publisher, AAAS, thanks for joining us.