A Risk Map depicts which geographic regions are at greater or lesser risk for some specific event or condition. This image represents a sample risk map for the West Nile Virus in North America. This image was created in support of a story describing how NASA is assisting the CDC and EPA in tracking the spread of West Nile Virus. Note: A sample West Nile Virus risk map for North America. Animator: James W. Williams (GST). Scientist: David Rogers (Oxford University).