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For these virus-hunting scientists, the 'real gold' is what's in a mosquito's abdomen

Damaris Sanchez looks at the mosquitoes caught in a house at the village of Los Encuentros, Coatepeque, Guatemala, October 4, 2022.
Luis Echeverria for NPR
Damaris Sanchez looks at the mosquitoes caught in a house at the village of Los Encuentros, Coatepeque, Guatemala, October 4, 2022.

It's early morning in banana farm country in the lowlands of western Guatemala, about 10 miles from the Mexican border. The sun has just started cooking the air into a tropical soup. Crop-dusters zigzag across the sky, casting shadows on the roofs of half a dozen low-slung buildings. One is a health clinic, another is a laboratory. This is the Fundación para la Salud Integral de los Guatemaltecos, or FunSalud for short.

About half past 8, a couple of dozen junior researchers spill out of a building, jump into their three-wheeled red and green tuk-tuks, and fan out onto the rural roads. Research coordinator Neudy Rojop is behind the wheel of one of them. The ride is bumpy, jostling her up and down, but she's unflappable. "We are visiting two homes with families that are participating in the project," she says through a translator.

Cecilia González and Damaris Sanchez leave the lab in a tuk-tuk to head into the community for a research project.
/ Luis Echeverria for NPR
/
Luis Echeverria for NPR
Cecilia González and Damaris Sanchez leave the lab in a tuk-tuk to head into the community for a research project.

Rojop is referring to a FunSalud study she's supervising in this community. The research team is helping test what could be a clever way to look for viruses — all kinds of viruses, but especially those that could cause serious and widespread illness in humans.

"We're trying to focus on pathogens that just happen to be in the blood that the mosquito happened to suck up," says Dr. Dan Olson, a research director at FunSalud and a pediatric infectious disease doctor at the University of Colorado's School of Medicine. The researchers are wagering that the earlier they can spot a virus that's circulating among people (as opposed to something the mosquitoes themselves carry, like dengue or yellow fever), the better the chances of stopping a global outbreak. That's when you can learn a pathogen's secrets, the scientists say — and then use that knowledge against the germs to vanquish them.

Rojop pulls up to a residence in the community of Chiquirines and cuts off the engine. The home has concrete walls and a metal roof and is one of 60 in the area that's enrolled in the study. Rojop hops out of her tuk-tuk and walks across the dusty yard. She passes a couple of pigs and skirts a band of patrolling chickens. Rojop grew up not too far from here. People in this area "usually see their animals as part of their families," she says.

When Rojop gets to the front of the house, she pulls out a big tube they've dubbed the "insectazooka." But instead of launching insects, the insectazooka's white PVC pipe sucks them in.

"Basically, it is a vacuum," says Rojop. "And we use it to vacuum the mosquitoes alive."

Mosquitoes are a real nuisance here. Celia Alvarez is 60 and lives in this home with her sister, niece, daughter and two grandsons. She wears a black top with pink hibiscus flowers blooming across it. Alvarez smiles as she hits her arm, as if to swat the insects, saying that she usually just slaps them into oblivion.

But Neudy Rojop doesn't want squished mosquitoes. Instead, the real gold is what's in their abdomens. "Blood," she says.

The researchers want mosquitoes to do the work for them, like a swarm of flying syringes, sampling the blood of every pig, pet and person on the premises. The community members say they like this approach of disease surveillance because it doesn't involve a single needle to draw blood.

When the team members analyze that blood, they are looking for any viruses the mosquitoes may have slurped up — those known and, maybe one day, those the world has never seen before.

Neudy Rojop sucks up mosquitoes with the insectazooka, sweeping the device into the dark corners of the house, under the beds and into the crannies.

Luis Escheverria for NPR

Why they're sucking up mosquitoes

There's good reason to search here.

Dr. Edwin Asturias, an infectious disease pediatrician at the University of Colorado, co-founded FunSalud a decade ago. Asturias, who's from this part of Guatemala, says it's a good place to look for spillovers — when a disease crosses from animals to people — for two main reasons. The first is that people and animals live so closely together.

"Because they are in a crowded condition," he explains, "the ability for any pathogen to move from the animals to the human is much higher. Maybe the pig is having a cold and now, suddenly, that influenza virus is going to transfer to a little child."

Viruses frequently shuttle between animals and humans. The vast majority of the time, attempts by a virus to move from a pig, say, into a human tend not to be too troublesome. "But in some cases," says Asturias, "the more you give the virus the chance to interact with humans, the more it's just going to adapt to be amongst the humans, mutating in a way that may become dangerous."

The second reason why it's worth doing disease surveillance in rural Guatemala has to do with the general health of the population. Many people here suffer from high rates of malnutrition, which makes them more vulnerable to disease, says Asturias. "To top it off," he adds, "their parents, who have survived those illnesses when they were young, are suffering now huge amounts of chronic illnesses." That includes renal failure, obesity, hypertension and diabetes.

Illness is like a well the residents here can't ever quite climb out of, says Asturias, and it weakens their immune systems over time. This means that it's possible for viruses — including those from animals — to sit and stew for longer.

"Therefore, if there's things that are going to emerge in the next few years," says Asturias, "it's better if you keep an eye on them all the time and intervene earlier ... if we want to think about providing a better control and prevention of infectious diseases in the future."

The mosquitoes go for one last ride

Cecilia González sorts mosquitoes under a microscope. She's looking for females with blood meals.
/ Luis Echeverria for NPR
/
Luis Echeverria for NPR
Cecilia González sorts mosquitoes under a microscope. She's looking for females with blood meals.

Back at the home in Chiquirines, the vacuum finishes yanking the mosquitoes from their hideouts. The operator quickly screws a cap onto the end. You can hear the trapped insects buzzing around inside — 60 to 70 mosquitoes, unscathed.

Silvia Alvarez, who also lives there, is pleased. They'd be welcome to vacuum the whole house, she says.

With that small hoard of insects in the tube, Rojop takes them on a quick drive to the lab, where they're plunged into a deep freezer that kills them but keeps their blood intact to sample and study.

After 15 minutes, Rojop's colleague, Cecilia González, pours the mosquito carcasses onto a petri dish, which she then pushes under a microscope. She sorts them by species and zeroes in on females that have recently feasted. One mosquito's abdomen is swollen with blood.

González puts that insect onto a piece of absorbent paper. Tweezers in hand, she takes off the head and carefully squeezes the mosquito. A tiny droplet of blood seeps out, soaking into the paper. This and other samples like it will be shipped to the Ebel Lab at Colorado State University for analysis.

Looking at that crimson dot, you can't help but wonder: Could some dreadful new virus be swimming in there?

The team will scan the blood of the mosquitoes for any human or animal viruses they may have slurped up — those known and, maybe one day, those the world has never seen before.
/ Luis Echeverria for NPR
/
Luis Echeverria for NPR
The team will scan the blood of the mosquitoes for any human or animal viruses they may have slurped up — those known and, maybe one day, those the world has never seen before.
Mosquitoes captured in a village are viewed under a microscope at FunSalud. The researchers hope to use the insects as a way to sample the blood of people and animals without using a single needle.
/ Luis Echeverria for NPR
/
Luis Echeverria for NPR
Mosquitoes captured in a village are viewed under a microscope at FunSalud. The researchers hope to use the insects as a way to sample the blood of people and animals without using a single needle.

The researchers on the FunSalud team have another pressing question: Is this whole new approach to surveillance actually going to work here?

"It's a very interesting and innovative way of monitoring or surveillance," says Asturias, "if it proves to be right. We have to still prove the concept. But I'm very confident that the technology that we are developing is getting us to detect pathogens faster."

So far, they have been able to detect a couple of known animal and human viruses (i.e., Epstein-Barr and canine distemper) in blood harvested from mosquitoes in Liberia. The team is still testing and refining its approach in Guatemala.

"We have to be on the lookout all the time," says Asturias. That's because the stakes for missing something small couldn't be bigger.

The Center for Human Development at Trifinio clinic in San Vicente Pacaya, Coatepeque, Guatemala, where mosquito blood meals are being analyzed by researchers.
/ Luis Echeverria for NPR
/
Luis Echeverria for NPR
The Center for Human Development at Trifinio clinic in San Vicente Pacaya, Coatepeque, Guatemala, where mosquito blood meals are being analyzed by researchers.

Ana Lucia Laparra served as translator for the reporting team.

Copyright 2023 NPR. To see more, visit https://www.npr.org.

Ari Daniel is a reporter for NPR's Science desk where he covers global health and development.