Tracking the spread of Zika

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

TRANSCRIPT

> 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.

Here's the story.

Scientists have confirmed the Zika virus is spread through bites from mosquitos of the species.

It's the same mosquito that spreads dengue fever.

But just how does a mosquito bite create a worldwide epidemic?

Most of what epidemiology was doing is looking at the occurrence of disease, and so what we want to look at is the evolution of disease, the evolution of the pathogens themselves, the bugs themselves.

And so, using evolutionary biology techniques and genetics, we can connect all those cases and see how pathogens are moving over space, time, different host organisms.

Dr. Daniel Janies threw a lot of computing power behind that question and created an eye-opening view of the worldwide spread of a disease.

Okay.

So, here, it's spreading throughout Africa, all right?

Zika was first identified in the Zika Forest in Uganda in 1947.

It's considered a mild disease in Africa.

And the virus stayed in Africa for almost 20 years.

And then it moves to Malaysia, and, going forward to about 2007, it spread to Yap in Micronesia.

And going forward from there, 2013, it spread to French Polynesia.

And now we're seeing, in 2014, 2015, it's spreading through the Caribbean, South America, and Central and Mexico and North America.

And what's happened as it crossed the Pacific is it's mutated a little bit.

Those genetic mutations provided valuable insights to the team at UNC Charlotte, who have placed interactive tracking of the Zika virus at the world's fingertips.

It's much like, you know, projectors projecting an image on the screen, and that gives us both the evolutionary context, the time context, the host context, the mutation context, and the geo context all in one.

The red dots on the map are key.

They represent a sample of the virus taken from a patient.

That blood sample is used to sequence the virus' DNA.

Researchers contacted governments, hospitals, and private labs all over the world to gather the information.

The result shows that not only how the Zika virus spreads, but also its family tree.

I may try to call those labs and ask them, 'Do you guys have those samples in your freezer?'

And if they say yes, then we're like, 'Okay, would you be willing to collaborate with us so we can do sequencing for you guys on those sequences, work together, and gather sequence and understand to do a forecast?'

And that helps the public health, of course.

The team hopes its maps will help in understanding how the virus spreads and changes.

Mosquitos don't travel far, but in a world in which people move about, it doesn't have to for the virus to spread.

A mosquito bites an infected patient.

The Zika symptoms are flu-like -- aches, pains, and fever.

They last about seven days.

The mosquito bites the infected patient... [ ] ...then flies and bites a person who doesn't have the virus.

[ ] That spreads the illness.

What's amazing to me is that that transit across the Pacific, that's a virus that relies on mosquitos -- which are flying across the Pacific -- relying on people flying across the Pacific or otherwise, you know, taking a ship and infecting the local mosquito population, infecting other people on the island, and somebody's unlucky enough to go to the next island.

Researchers theorize that the virus mutates as it spreads and it's those mutations that are linked to the birth defects Zika is believed to cause.

So, what is the relationship, then, between, say, this and this and that over there in -- Haiti I think it is?

Yes.

So, they are sisters that share a common parent, and that parent has other parents and so forth.

Researchers even added a feature to the map to show the relationships between strains of the Zika virus.

So, here, you've got in West Africa two sisters with a common ancestor.

And what the particle guide helps us visualize is the flow of information down from the deep ancestry of the virus, down to the surface of the earth where the actual viruses are happening.

Bottom line -- while the Zika virus, now linked to a surge in birth defects in Central and South America, was first identified in Africa roughly 60 years ago, it is not the same virus.

It has mutated.

We really like to show translation over geographical space.

It really kind of helps get an understanding of how the diseases flow.

These viruses were isolated out of patients not long ago.

We're putting it all in a context, and it's very much akin to, like, you turning on the 6:00 news and seeing a weather map of storms coming across the middle of the country to North Carolina.

Here, we're seeing a virus moving across the world, potentially affecting North Carolina.