Virus Tracking

Viruses like influenza, Ebola and Zika can spread widely around the world through shipping, travel and other ways we humans move things from one place to another. DNA sequencing can provide a roadmap that a virus has followed to get where it is today. Watch as researchers use DNA sequencing to create a powerful tool to track the spread of the Zika virus around the world.

CHARLOTTE  — Scientists have confirmed the Zika virus is spread through bites from mosquitos of the aedes (a-deez) species: the same mosquitoes that spread dengue fever.

But just how does the bite of a mosquito, which doesn’t fly very far, create a worldwide epidemic? Daniel Janies, Ph.D., a professor of Bioinformatics and Genomics at the University of North Carolina at Charlotte, has created a computer program that provides an eye opening view of the worldwide spread of the disease.

“Most of what epidemiology looks at is the occurrence of the disease,” explains Janies. “But we wanted to look at the evolution of the disease and the evolution of the bug itself, the pathogen. So we used evolutionary biology techniques and genetics to connect all of the cases and see how the pathogens are moving over space, time and different host organisms.”

Zika was first identified in the Zika forest in Uganda in 1947. It’s considered a mild disease in Africa. And Janies‘ model shows the virus staying in Africa for almost 20 years.

“But then things change and it starts to move,” says Janies, as he stands in front of a television screen with a Google Earth image of the world in the center.  There are red dots connected by white lines over the middle of the African continent.

A cursor moves along a timeline on the left side of the screen.  As the arrow passes over 1966, the white line arcs from Africa to an island in the Pacific Ocean.

"The virus spreads in Africa, but stays on the continent until 1966 when it moves to Malaysia, “ says Janies, as he points to white lines across the middle of Africa and then over the Malaysia.  The cursor then moves further up the timeline. The white lines arc again, further into the ocean. “Then going forward to 2007, it spreads to the island of Yap in Micronesia, and then in 2013 it moves into French Polynesia.”

Lastly, as the cursor moves up to 2014, the white arcs move into South and Central America. 

“And now we’re seeing in 2014 and into 2015, the virus moves dramatically into the Caribbean, South America, Central America, Mexico and to the edges of North America,” says Janies. “And we find that the virus has mutated a bit as it crossed the Pacific.“

Those genetic mutations provide valuable insights to Janies and his team at UNC Charlotte, who have placed interactive tracking of the Zika virus at the world’s fingertips.

The red dots on the map are key. They represent an sample of the virus from a patient. That blood sample is used to sequence the virus’s DNA.

Researchers contacted governments, hospitals, and private labs all over the world to gather the information. The program created from all those samples shows not only how the Zika virus spreads but also the virus’ family tree.

“I called many labs to ask if they have a sample from a patient with Zika, and if they did, could we collaborate and get the information,” explains Adriano DeBernardi Schneider, a Ph.D. student at UNC Charlotte.  “It’s important to get the data so we can visualize what is happening and better understand the history of the virus and where it might go, which is important to the public health.”

The symptoms of the Zika virus are flu-like; aches, pains, and fever. They are usually mild and last about seven days.  Many people don’t even realize they are sick. 

The virus itself is spread by a mosquito bite.  After the infected patient is bitten, the mosquito then flies and bites a person who doesn’t have the virus. The virus is transmitted through the bite. 

The mosquito doesn’t travel far. But in a world in which people move about, it doesn’t have to travel far to spread the virus.  Janies admits that is one of the most surprising discoveries in his research.

“Here you have a virus that relies on mosquitoes to spread,” says Janies. “But mosquitos don’t fly across the Pacific, so the virus counts on people flying or taking a ship, and infecting the local mosquito population, and infecting other people on the island, and then finding somebody unlucky enough to go the next island.”

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

To show those mutations, researchers added a feature to the program to illustrate the relationships between strains of the virus.  For example, in West Africa, there appears to be a “T “stop.  The white virus arc extends from East Africa to a red dot in West Africa, which then splits the white line into two branches. Janies explains that signifies a common parent virus which then splits and mutates.

The bottom line from the project: while the Zika virus currently linked to a surge in birth defects in Central and South America was identified in Africa roughly 60 years ago, it is not the same virus. It has mutated. 

“We really want to show the translation of the virus and how it changes and moves over geographical space,” says Zach Witter, a research engineer who helped create the program. “It helps to get an understanding of how the Zika virus and other diseases flow, because this program can be applied to many illnesses.

“The truly useful thing about this program is that we’re collecting real time genetic information because these viruses were isolated from patients not long ago,” explains Janies as he looks at once again at a globe covered with white arcs. “And much like you’re turning on the news and you see a weather map with an image of a storm coming, you can look at this and see a virus moving across the world and possibly affecting North Carolina.”


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