Choropleth map of Population density, Congo River and Wild Polio virus cases. KML layers resulted in high quality visual display and can improve our understanding of the spatiotemporal relationships between the entities involved in the polio outbreak. Colours and values for population density classes were chosen by the author and may not conform to existing standards. Markers are custom Portable Network Graphics (PNG) images designed with Macromedia Fireworks™. Disclaimer: The map is intended solely to demonstrate the use of Google Earth™ in public health mapping and has no other intentions whatsoever. Refer to authoritative sources for disease and population information about the Democratic Republic of Congo.