With an estimated 500 million people infected each year, dengue ranks as one of the most significant mosquito-borne viral human diseases and one of the most rapidly emerging vectorborne diseases (1) . A variety of obstacles including bureaucracy and lack of resources have interfered with timely detection and reporting of dengue cases in many endemic countries (2) . Surveillance efforts have turned to modern data sources, such as Internet search queries, which have been shown to be effective for monitoring influenza-like illnesses (3, 4) . However, few have evaluated the utility of web search query data for other diseases, especially those of high morbidity and mortality or where a vaccine may not exist.