These methods are the basis for at least one deployed, widely
used surveillance system. Based upon search query data, Google
Flu Trends offers near-real-time estimates of influenza activity in
29 countries across the world (15 at the province level); another
facet of the same system, Google Dengue Trends (http://www.
google.org/denguetrends/) estimates dengue activity in 9 countries
(2 at the province level) in Asia and Latin America.