The fight against Zika

With the global spread of Zika, epidemiologists in North Carolina are tracking the evolution and geographic spread of the virus, from when it was first identified in 1947 to today.


Scientists in Orlando, Florida, are fighting back against Zika.

We go into the field and into the lab, where researchers are working towards stopping the virus in its tracks.

Here's the story.

Before 2015, few people had ever heard of the Zika virus.

Then, news broke of an epidemic in Central and South America.

In the vast majority of cases, infection is asymptomatic or brings mild flu-like symptoms.

But in the unborn babies of pregnant women, it can cause a severe birth defect called microcephaly.

In adults, infection occasionally leads to serious complications and even death.

The Centers for Disease Control and Prevention estimates that by early 2017, nearly a million people in Puerto Rico will be infected.

Cases have started showing up in Florida.

And experts believe they can multiply rapidly.

In central Florida, efforts are underway to reduce the risk.. The virus is spread by mosquitoes.

So one way of fighting Zika is mosquito control.

Right here is almost subtropical.

Right here is some of the same weather that's in the Caribbean.

The weather is warm almost all year long.

The mosquitoes got a great chance to breed right here, faster than in northern states.

Amador Rodriguez is searching for two species of non-native mosquitoes known to carry Zika.

We're looking for water sources.

The water sources, that's where the mosquitoes gonna breed.

That's where the mosquitoes gonna lay their eggs.

That's where they're gonna incubate and hatch.

The main concern is try to get the people safe.

The mosquito will lay the eggs there.

When our field inspectors are out looking for sources, they are looking for any little thing possible that can hold water enough to breed mosquitoes.

Inspectors collect mosquito larvae and bring them to this Orlando lab to be analyzed.

The mosquito female, after it's taken a blood meal, it develops its eggs.

And it can lay up to 200 eggs per batch.

And those mosquito eggs have to dry out for 12 to 24 hours.

And then once they get wet, they hatch into little larvae.

And the larvae have four parts to their life cycle.

It just takes about 5 days to go through that larval life cycle.

And then they're off and flying.

Officials use data on where the larvae were collected to determine where to spray, being careful not to target harmless local species of mosquitoes that form an important part of the ecosystem.

They are pollinators.

And they're part of the food chain.

There's lots of things that eat them as larvae.

Fish eat them. Frogs eat them.

Some other aquatic organisms eat them.

But as adults flying around, there's lots of birds that eat them, bats.

There's just quite a few things that will eat them.

But some researchers believe sprays are ineffective against the two species that spread Zika.

These mosquitoes don't swarm at night, when spraying usually takes place.

Female mosquitoes are the only mosquitoes that bite.

Florida International University neurogeneticist Matthew DeGennaro regularly meets members of the public to answer questions about Zika.

I'm trying to get pregnant this year, not the best time, obviously.

He and other experts believe genetically modifying mosquitoes might be more effective than spraying.

One way is to release male mosquitoes, which don't bite, that will species-specifically find Aedes aegypti female and render her functionally sterile and unable to reproduce.

And so we can achieve population reduction through this mechanism.

And it has been done in the Caribbean.

It's been tried in Brazil.

And I think that it's a lot better than spraying, which affects so many different insects What we need to focus on is reducing just the Aedes aegypti and albopictus possibly, as well, their populations.

Another approach is to modify the DNA in mosquitoes to react differently to smells such as a human odor.

The first step is to figure out which receptors in the mosquito's brain cause it to be attracted to humans.

And then we can try to find a chemical to hijack those receptors.

And then we can cause the mosquito to be like, 'Oh, my God. Yuck. Stay away.'

So it would almost be like a designer perfume that is designed to annoy mosquitoes.

We think that understanding how a repellant works will help us design the next generation of repellents.

But techniques like these are likely years from being practical.

Meanwhile, officials on the ground know they have to try many options.

Especially with these two species, we cannot spray our way out of this because they're so elusive.

And they're hard to control, their habitats.

And there's little bits of water all over the place.

When we do hear about risks in other areas, we're very quick to learn about things that are going on and what's working to control.