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For years, it seemed like Papua New Guinea was on a course to stamp out malaria. In 2010, the total number of suspected malaria cases in Papua New Guinea was 1.7 million. By 2015, the number had been cut nearly in half. Experts believed the country could see a malaria-free future as soon as 2030. But then, something changed — and cases started climbing again, as quickly as they had fallen. 

In today’s episode of the Big Take podcast, Bloomberg health care reporters Anna Edney and Michelle Fay Cortez unpack how a single business decision made by the world’s biggest manufacturer of bed nets reversed years of work to eradicate malaria in a country that — at least for a while — was on track to beat it.

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Here is a lightly edited transcript of the conversation:

Sarah Holder: Tim Freeman’s work takes him to some of the most remote places in Papua New Guinea. 

Tim Freeman: PNG, for those who don’t know it, is a very, very complex country in terms of terrain. We’ve got lots of mountains and suchlike, and getting stuff is very expensive. And often we have to go to places with airplanes and sometimes even helicopters. 

Sarah Holder: Those helicopters, that traversing mountainous terrain, it’s all part of an important mission that Tim’s been chipping away at for decades.He’s the program manager of Rotarians Against Malaria, an NGO funded by The Global Fund and partnered with Papua New Guinea’s National Malaria Control Program. And their goal is to eliminate malaria in the country.

Tim Freeman: I have a team of people here that we literally jump from one province to another every one to two months. And basically this team of people work with the local health authorities. And we literally visit every village.

Sarah Holder: Tim says they do a census, checking every household in every village of the country, for the purpose of distributing mosquito nets.Malaria is transmitted almost entirely through mosquitoes who carry the disease. And in the poorest parts of the world, one of the primary tools against these mosquitoes are insecticide nets that can kill them before they bite and infect someone.

Sarah Holder: How many nets total have you distributed over your time there?

Tim Freeman: Oh, overall, since we've been here, about 20 million nets, I think.

Sarah Holder: And for a while, it really seemed like their strategy was working.

Tim Freeman: By the time we got to 2015, the number of cases that we're recording in the country was half of what it was in 2006. So everybody here was very excited, thinking, right, we're on the way to elimination.

Sarah Holder: In 2010, the total number of suspected malaria cases in Papua New Guinea was 1.7 million. By 2015, there were only around 900,000. And Tim says it looked like the country was on track to completely eliminate malaria by 2030. But then... something changed.

Tim Freeman: All those dreams disappeared very quickly.

Sarah Holder: Today on the show: why researchers say a single business decision made by the world’s biggest manufacturer of bed nets reversed years of work to eradicate malaria in a country that — at least for a while — was on track to beat it. I'm Sarah Holder and this is the Big Take from Bloomberg News.

Michelle Cortez: Malaria is a horrifying disease. It is a high fever, shaking, and chills. You have trouble breathing, diarrhea, abdominal pain, fatigue. You suffer. People with malaria suffer.

Sarah Holder: That's my colleague Michelle Fay Cortez. She's a global healthcare reporter and senior editor at Bloomberg. And she broke down why malaria is such a high stakes disease.

Michelle Cortez: It can be very quickly fatal. People can die within 24 hours with malaria, and it's not the sort of thing that you recover from quickly. It takes weeks and months. It's just a terrible disease.

Sarah Holder: Malaria can be devastating for individuals and families. But it can also have an impact at scale. The World Health Organization, or WHO, estimates the disease is responsible for dampening the GDPs of some African countries by 1.3%. And in its most recent malaria report, the organization says as much as half of the world's population is now at risk—including some parts of the US. One of the most effective tools for combating malaria was developed at the turn of the century: long-lasting insecticidal nets.

Anna Edney: That's a fancy name for a net that is coated in insecticide.

Sarah Holder: That's my colleague Anna Edney. She also covers healthcare at Bloomberg. She and Michelle teamed up on this reporting, and you'll hear from both of them in the episode. They say all their sources agreed… that these nets that came with insecticide built in were a total game-changer.

Anna Edney: Before these were invented, villages were receiving nets and they were having to dip them in the insecticide themselves. And then, when you wash them, that can cause problems. You need to dip it again. And so it's laborious.

Sarah Holder: Laborious… and they didn’t work as well. These new, pre-treated nets were much more effective. And the results spoke for themselves. Mosquito populations would plummet in the communities where they were widely used. And malaria cases went down with them. 

Michelle Cortez: When you look cumulatively over the course of time, the impact of these insecticide-treated nets is just amazing. One of the few public health measures that has really made a significant difference on one of the leading causes of death in the developing world.

Sarah Holder: For a long time, all the insecticide-treated nets in Papua New Guinea came from one source: A Swiss company called Vestergaard.

Michelle Cortez: Vestergaard has an amazing reputation for quality. They were one of the very first companies to get involved in this space, and everyone told us they were the gold standard—that the nets that they were putting out and the other efforts that they had made when it comes to public health were really top notch.

Sarah Holder: Thanks to Vestergaard’s nets, it looked like the country was on track to a malaria-free future. But between 2015 and 2022, something shifted. Researchers found that the annual number of malaria cases in Papua New Guinea nearly doubled, completely erasing the progress Tim and his team had seen. So what happened? That’s after the break. 

Sarah Holder: We’re back. From 2006 to 2015, Papua New Guinea was on course to wipe out malaria from the country, largely thanks to an insecticide-laced mosquito net from the Swiss company Vestergaard.  But in 2016, cases started to climb. And researchers wanted to know why. Over the next five years… as the problem continued to worsen… they considered a lot of possibilities: climate change, mosquitoes growing resistant to the insecticides, the list goes on. The country had reserves of unopened Vestergaard nets going back to 2007. And they were able to test their effectiveness at killing mosquitoes from year to year. 

Anna Edney: They found that the nets worked much, much better prior to 2012, 2013. And they actually got worse in the later years. They were only about 17% effective, compared to 100% effective before 2012.

Sarah Holder: A team of researchers published those findings—that the older Vestergaard nets were much more effective than the newer ones—in a peer-reviewed journal in 2020. But they still didn't know why it was happening. How could these nets, which were touted as the gold standard in the fight against malaria, suddenly drop off in quality?

Michelle Cortez: They really couldn't figure it out, and they did try for quite some time.Then some researchers from Papua New Guinea went to a meeting in Liverpool, actually, and they came across another expert in chemical coatings. And that person said, have you actually looked at the way the nets were made—at what was being put on the nets to see if there was a change there. So that's when a light bulb moment occurred and the researchers sent off the nets and found out, in fact, that there had been a change in the coating of the netting that happened in 2012, 2013, and that that is what they believe was the cause of the issue.

Sarah Holder: It would turn out that right around 2012 and 2013… Vestergaard changed the way it bonded the insecticide to its nets. Up until that point, to get the insecticide to stick to the net for years... even after multiple washes... the company had used what are known as...

Anna Edney: Polyfluoroalkyl substances, which you might know as PFAS or, forever chemicals.

Sarah Holder: PFAS chemicals have historically been used in things a lot of us use everyday... from nonstick cookware to water-repellant clothing to stain-resistant fabrics and carpets. But even if PFAS chemicals are really good at getting insecticide to stick to mosquito nets... they're not without their own risks.

Anna Edney: There's a cancer risk that's associated with PFAS as well as potentially developmental issues for kids. So, not great to have that in the coating.

Sarah Holder: Anna reached out to Vestergaard to ask the company why it had decided to stop using PFAS chemicals in its manufacturing process.

Anna Edney: Vestergaard said that they changed the nets because the supplier that they got the ingredients for the coating from stopped selling the PFAS material, and that they needed to change that. They didn't say who the supplier was, but they said that they decided to go with a different ingredient, which they didn't tell us what the ingredient was. 

Sarah Holder: To report this story, Anna and Michelle spoke with more than three dozen malaria and net experts, business leaders and industry consultants from around the globe. And while Vestergaard told Bloomberg that it had stopped using a PFAS coating because of supplier issues… Anna and Michelle also talked to two consultants with knowledge of net technology… including one who used to work at Vestergaard and asked not to be named. And they said Vestergaard could have chosen a more effective substitute for PFAS chemicals… and the fight against malaria in Papua New Guinea wouldn't have lost as much ground… if only the company had decided to go with a more expensive option. They said the reason the nets stopped working as well… was because the company had picked a cheaper replacement. 

Anna Edney: They had different options that they could have gone with, but they decided to go with this option.

Sarah Holder: How has Vestergaard responded to that criticism and the allegation that the nets are less effective?

Anna Edney: So they haven't acknowledged that the nets are less effective. They have acknowledged that there is a broad range of what can be considered an effective net and that they still fit into that category. So they still meet WHO's criteria for being a net that can be sold to prevent malaria, but they still aren't as good as they once were.

Sarah Holder: Until 2017, the who did not require net manufacturers to inform them of manufacturing changes. And Vestergaard didn’t disclose the change to their nets. But that had wide implications.

Michelle Cortez: The thing is, is that at the time, the company didn't notify the World Health Organization that they were changing the way they made the bed nets, and they didn't tell anyone who was being affected by that. They also didn't tell anyone when we started seeing these rates increasing. And as people on the ground in Papua New Guinea were trying to figure out what was going on, they also didn't say it then.

Sarah Holder: Anna's done a lot of reporting on healthcare products that don’t work as well as they’re supposed to. And she says the story of Vestergaard in Papua New Guinea is an example of what can happen when the balance between cost and quality is thrown off.

Anna Edney: One thing that was reinforced when I was reporting is that when, particularly in public health, we're looking at products that we're trying to buy for either medicine or preventing disease—anything along those lines—that just buying the cheapest thing, is not always going to be the best.

Sarah Holder: Papua New Guinea has been able to secure nets made by other manufacturers. But Vestergaard is still producing and distributing its nets all over the world. The company contests the methods that researchers used to show that their nets were less effective than before. But the World Health Organization has told Bloomberg it is very concerned by the implications of the research. They’ve asked for the underlying data to look into it more. The WHO has also raised concerns about the quality of nets manufactured by other companies, and in other countries. This issue is not unique to Vestergaard. And compounding trends in the industry—like growing global demand for nets and more competition among suppliers—have some researchers worried that the quality of these life-saving nets will only continue to drop. Tim Freeman says they’re feeling the effects of those shifts on the ground  in Papua New Guinea.

Tim Freeman: The simple message here is that the nets that we are receiving now, not only from Vestergaard, don't seem to be as good as the ones that we had in the past. So this is not just a problem for Vestergaard, it seems to be right across the board. What I want to see is a new generation of nets that are much more efficient than the previous ones that we have been distributing for the last 10 years.

Sarah Holder: Though today’s nets aren’t perfect, Anna and Michelle’s sources emphasized that having nets at all is better than having no nets, even as people on the ground advocate for better ones.

Michelle Cortez: Everyone that we've talked to has said, you know, please don't denigrate nets. We need people to believe in the nets. We need the funders to pay for the nets. We need the doctors to distribute the nets. We need the people on the ground who are dealing with malaria and their daily rates to believe in the nets, and to use them to put their kids under them, to sleep under them every night. But that doesn't mean that they're as good as they can be. It doesn't mean that they're as good as they used to be and that's something that we really do feel like should be a discussion in public health circles.

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