Google Flu á la Sweden

The fact that the spread of flu could be predicted by tapping into searches on Google, gained much attention during 20098-9. (See however here). The idea to tap into web searches to find early warnings of disease outbreaks seems to be spreading, this time however, applied on something that Swedes know far too well: the extremely infectious norovirus. The virus is known to give nausea, vomiting, diarrhea, and abdominal pain.

A research team at the Swedish Institute for Infectious Disease Control, recently published data showing that queries for *vomit* (asterisks denote any prefix or suffix) submitted to the search engine on a medical website in Sweden (, match the number of laboratory-verified cases almost perfectly (see figure).

Figure. Number of queries for *vomit* submitted to a medical Web site (blue), number of laboratory-verified norovirus samples (red), with baselines and 99% prediction intervals, and number of media articles about winter vomiting disease (black) in Sweden, 2005–2010. From: Hulth A, Andersson Y, Hedlund K-O, Andersson M. Eye-opening approach to norovirus surveillance [letter]. Emerg Infect Dis. 2010 Aug:

The original article in Emerging Infectious Diseases can be found here.

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