Why the threat of mosquito-borne diseases is on the rise worldwide

John Yang:

With that annoying buzzing your ear the itching bite that leads to frenzied scratching. For many of us here in the United States mosquitoes are merely a summertime nuisance. But Ali Rogin is back to tell us that around the world, mosquitoes and the diseases they carry are a growing public health concern.

Ali Rogin:

The tiny mosquito is responsible for more deaths than any other animal, killing billions over the course of human history. Mosquitoes transmitting malaria killed more than 600,000 people in 2021. In that same year, another 247 million people were infected.

Now these deadly vectors of disease are expanding their reach, showing up in parts of the world never seen before.

A new multi-part investigation by the New York Times looks at the global fight against mosquito borne diseases, and how years of progress in that battle have been reversed. Stephanie Nolan covers global health for the New York Times, and spent a year tracking mosquitoes and the diseases they carry.

Stephanie, thank you so much for joining us. As we just mentioned, humans, we're winning the war against malaria, against mosquito borne diseases for so long. But you write in this series that now mosquitoes are winning, what changed?

Stephanie Nolan, Global Health Reporter, The New York Times:

What changed is that mosquitoes are crafty, Ali. They evolve very quickly. Every generation of mosquito has lots of mutations, it means that they're very good at developing resistance, the things that we come up with to kill them. So mosquitoes around the globe are resistant to the insecticides.

And so every time we come up with something that we think is going to be the silver bullet to fight back, mosquitoes get around it. And of course, the time differences in mosquito generation is six or 710 weeks, whereas designing testing and bringing to market and anti-mosquito product generally takes a minimum of 10 years.

Ali Rogin:

It does seem though, that mosquitoes are getting seemingly even more impervious to these efforts. Have we hit a real perfect storm here?

Stephanie Nolan:

No, I don't think so. And I'll tell you after a year of looking at this, I'm still kind of hopeful. I think you're really right to be you know, striking a note of alarm, because we're seeing mosquitoes that carry viruses like Dengue fever and Chikungunya turning up in places like France and the southern United States that have never had that problem.

I wrote about an invasive mosquito from Asia that's now gone into Africa and is threatening African cities with malaria, which maybe doesn't sound so shocking, except that malaria is a rural problem in Africa, not an urban one.

And so this puts hundreds of millions of new people at risk. But in places that don't have the infrastructure to respond, because of climate change, you're seeing dangerous mosquito species adapting to live in all kinds of new places.

And I also looked at Big Picture projects at big efforts. One of them is genetic modification of mosquitoes so that they wouldn't be able to transmit disease, those kinds of strategies that might work for multiple diseases and in multiple places. Those are the ones that I think, keep me from completely panicking.

Ali Rogin:

And you mentioned how some of these diseases Dengue gay have shown up in the United States. In Florida there were nine cases of malaria reported in U.S. states this last summer, how is it and why that this disease has made it to the United States to this degree?

Stephanie Nolan:

So you know, nine cases is maybe not yet a cause for panic. I would say that, that those malaria outbreaks are like a tiny little like just a little, hey, you should be paying attention to this because we're starting to lose the grip do I think there's going to be tens of thousands of malaria cases in the US south within the next couple of years? I don't.

What's really interesting to me about U.S. malaria, and the way that it reminded people that there is an issue is that it makes us think about how did we get rid of malaria in the U.S., right? Ultimately, what made a difference was where people lived relocating communities out of swampy vulnerable places, and making sure that people had adequate housing that protected them, we spend more than $22 billion a year fighting mosquitoes.

So, we could continue to pour money into those things, new chemicals, more poisons, more poisons, or we can talk about what kind of investment it would take to get the people who are currently vulnerable into the same kinds of standards of housing that protected people in the U.S. south who used to live in malarial zones.

Ali Rogin:

Who are the people that are the most vulnerable here?

Stephanie Nolan:

I would say to malaria. It's as always, it's the poorest people in the poorest places. Tanzania has one of the highest malaria burdens in the world. 80 percent of the cases in Tanzania take place in the people who live in the 10 percent lowest quality of housing, right. So poorest people, poorest places.

Dengue fever and the arboviruses I think are going to be an interesting one to watch Dengue Zika yellow fever Chikungunya, the mosquito that carries them is not you know, biting people in fact houses in rural in Tanzania.

It lives happily in cities. It'll live on the balcony of your chic apartment building in Miami, it will breed our, you know, around your house, it will live in your closet. And so it has a much more equalizing effect in lots of ways. Many of us are either now or soon to be vulnerable to these mosquitoes.

Ali Rogin:

Stephanie Nolan with the New York Times. Thank you so much for your time.

Stephanie Nolan:

It's a pleasure.