Volume 15, Number 8—August 2009
Letter
More Diseases Tracked by Using Google Trends
Appendix Figure

Appendix Figure. Time series of search queries plotted along the incidence of 3 diseases (influenza-like illness, gastroenteritis, and chickenpox), 2004-2008. Black lines show trends of search fractions containing the French words for influenza (A), gastroenteritis (B), and chickenpox (C). Red lines show incidence rates for the 3 corresponding diseases (influenza-like illness, acute diarrhea, and chickenpox). Search fractions are scaled between 0 and 100 by Google Insights for Search's internal processes (5). Incidence rates are expressed in no. cases for 100,000 inhabitants, as provided by the Sentinel Network (4).
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