León municipality in Nicaragua and map of the León health and demographic surveillance system clusters. The small map in the bottom left corner of the figure shows the location of León municipality within the country of Nicaragua. The municipality of León has an area of 820 km2, making it the second largest city in Nicaragua . The dark grey and black areas in the larger map represent the clusters that form the León Health and Demographic Surveillance System. Cluster sampling was conducted in each territory of the municipality of León: Perla, Sutiava, and Mantica. All three territories include both rural and urban areas.