Norovirus disease surveillance using Google Internet query share data.

Google Internet query share (IQS) data for gastroenteritis-related search terms correlated strongly with contemporaneous national (R(2) = 0.70) and regional (R(2) = 0.74) norovirus surveillance data in the United States. IQS data may facilitate rapid identification of norovirus season onset, elevated peak activity, and potential emergence of novel strains.