This National Geographic video highlights how deadly rainforest viruses have transported from their animal hosts, and across continents. West Nile Virus is an example of how the world’s increased globalization has made people more vulnerable to deadly diseases. The virus is native to a very specific ecology of birds and streams in Africa. “No one could have imagined it [West Nile] could have emerged in the concrete jungle of Manhattan and Queens,” said Laurie Garrett, a science writer featured in the video.