Brazilians Have To Learn To Think Like A Mosquito | KUOW News and Information

Brazilians Have To Learn To Think Like A Mosquito

Feb 6, 2016
Originally published on February 6, 2016 7:27 am

You wouldn't think of calling a mosquito "man's best friend." But that's the nickname that biologist Denise Valle uses for Aedes aegypti, the species that's been spreading the Zika virus in Brazil and many other countries in Latin America.

I think "man's best enemy" might be better.

The thing is, this mosquito likes to live near humans.

Aedes aegypti breeds in shaded wet places — so cities are an ideal habitat — and feeds on us. It's the female that bites us and uses our blood to produce eggs. And the mosquito is not just a carrier for Zika virus. It also carries dengue fever and chikungunya,

The big question: How does Brazil control its mosquito population?

Aedes aegypti is one of the most difficult mosquitoes to eradicate in Brazil, Valle says. It's very inventive about finding wet spots to lay its eggs — open barrels, buckets, holes in the ground. And the mother mosquito is a brilliant strategist.

"The Aedes aegypti likes to lay its eggs in several places, giving its offspring a better chance to survive, and those eggs can stay viable for an incredible 450 days, in a kind of suspended animation," Valle says. "And they hatch in minutes once the rains come."

Which brings us, she says to Brazil's failure so far to control the mosquito. Yes, it's hard, she says, but both the authorities and Brazilians are to blame for the situation. She says in the rainy season — roughly December through February — everyone is combating the mosquito and talking about it. Come the dry months, and everyone forgets about it. But that's the best time to get rid of the breeding grounds.

She says the mosquito needs to be constantly battled.

But the average Brazilian, in my experience, isn't out there fighting mosquito wars.

Many people don't use repellent, they don't have screens on their doors they don't have screens on their windows. I ask Valle, "Why is that?"

She tells me that's part of the culture that needs to change. She believes that the government's anti-mosquito patrols have made people passive. They think it's the responsibility of health inspectors who do home visits to 'save' them from infestations.

I ask about reports I've read in the newspaper that the government might try to kill the mosquito with nuclear radiation.

Valle shrugs. They come up with something new every summer, she says. Some people have talked about using lasers to zap mosquitoes in midflight; others talk about using genetically modified mosquitoes.

She doesn't think any of the ideas are cost effective and practical for Brazil's megacities. Her advice is simple. Think like a mosquito — and hunt it in the places where it likes to live.

Copyright 2016 NPR. To see more, visit http://www.npr.org/.

Transcript

SCOTT SIMON, HOST:

This is WEEKEND EDITION from NPR News. I'm Scott Simon. This is what we know about Zika - there has been one case of sexual transmission in the current outbreak in Dallas. This week in Brazil, researchers announced they found active Zika virus in saliva and urine. Now scientists say the way most people get the virus is through mosquitoes - a mosquito species that also carries dengue and other infectious diseases. NPR's Lourdes Garcia-Navarro met with a specialist to discuss what Brazil should be doing to control its exploding mosquito population.

LOURDES GARCIA-NAVARRO, BYLINE: So we're going to be walking around today with Denise Valle, who is biologist who studies the Aedes aegypti mosquito. This is the mosquito that is really at the heart of the current crisis. It is really one of the most difficult mosquitoes to eradicate and to deal with here in Brazil.

DENISE VALLE: (Speaking Portuguese).

GARCIA-NAVARRO: She says, "If I had to name the mosquito, I would call it the opportunist because it is opportunistic in its daily habits."

VALLE: (Speaking Portuguese).

GARCIA-NAVARRO: She would also name it man's best friend - although I would probably say it was man's best enemy - because it always likes to live near humans.

The Aedes aegypti is in fact an urban mosquito, Valle tells me. It likes to breed in shaded, wet places and feed on us. It's the female that bites us and uses our blood to produce its eggs.

VALLE: (Speaking Portuguese).

GARCIA-NAVARRO: One of the reasons we're talking with her today is I wanted to get a sense of what the culture is here in Brazil regarding the mosquito. So we've come today, she says, to this apartment complex. This is an area in Rio de Janeiro's North Zone, which is working-class to lower-middle class.

VALLE: (Speaking Portuguese).

GARCIA-NAVARRO: She points to an area.

We're looking at this row of used tires, big truck tires, that are resting against a wall. And she says we know that water accumulates inside these tires. It's a favorite place for the Aedes aegypti to lay its eggs.

As we walk around the complex we see many places where the mosquito could breed - open barrels, buckets, holes in the ground. Valle, who is one of the leading experts in Brazil on this mosquito, says that it's very inventive and can be found where you least expect it, like inside a box air conditioner, which are commonly used here.

VALLE: (Speaking Portuguese).

GARCIA-NAVARRO: She's saying, "At this point, it would be impossible to completely eradicate the Aedes aegypti because of globalization, people coming and going all the time. Brazil has many frontiers that are quite porous with other countries." So one of the other issues is how long these eggs can survive.

VALLE: (Speaking Portuguese).

GARCIA-NAVARRO: The Aedes aegypti likes to lay its eggs in several places, giving its offspring a better chance to survive. And those eggs can stay viable for an incredible 450 days, in a kind of suspended animation. And then they can hatch in minutes once the rains come.

VALLE: (Speaking Portuguese).

GARCIA-NAVARRO: Which brings us, she says, to Brazil's failure so far to control the mosquito. Yes, it's hard, she says, but both the authorities and Brazilians are to blame for the situation. She says in the rainy season everyone is combating the mosquito and talking about it. Come the dry months, everyone forgets about it, but that's the best time to get rid of the breeding grounds. She says the mosquito needs to be constantly battled. So I ask her a question.

Brazilians, in my experience, they're OK living with the mosquito, cohabiting with the mosquito. Most people don't use repellant. They don't have screens on their doors. They don't have screens on their windows. Why is that?

VALLE: (Speaking Portuguese).

GARCIA-NAVARRO: She tells me that's part of the culture that needs to change. She says people in Brazil have to start taking responsibility for fighting the mosquito and protecting themselves. The government, she says, has also made people passive. People think it's the responsibility of health inspectors to do home visits to save them from infestations.

One of the things that I read in the newspaper today is that they are now going to take - see if they can kill the mosquito with nuclear radiation. Did you read this?

VALLE: (Speaking Portuguese).

GARCIA-NAVARRO: She says every summer there's something that they come up with, shrugging. She says some people have talked about lasers, zapping mosquitoes in mid-flight, others about using bacteria or genetically modified mosquitoes. She says she doesn't think any of these ideas are cost-effective and practical for Brazil's megacities. Her advice is simple - think like a mosquito and hunt it where you live. Everyone, she says, needs to do their part. Lourdes Garcia-Navarro, NPR News, Rio de Janeiro.

SIMON: For a map of Zika's spread in the current outbreak and in the past, you can go to the blog Goats and Soda, which is on our website, npr.org. Transcript provided by NPR, Copyright NPR.