UpToDate is an online clinical decision support resource that is used widely by clinicians around the world. Digital surveillance techniques have shown promise for aiding with the detection and monitoring of infectious disease outbreaks. We sought to determine whether significant increases in UpToDate search activity for selected infectious diseases predate or coincide with infectious disease outbreaks.
We analyzed daily searches related to Middle East respiratory syndrome (MERS) in Jeddah and Riyadh, Saudi Arabia during three hospital-based outbreaks in these cities in 2014 and 2015 and compared them with reported cases during the same periods. We also compared UpToDate MERS searches in the affected cities to those in a composite of four negative control cities for the two outbreaks in 2014. UpToDate MERS searches during all three MERS outbreaks in Saudi Arabia showed a correlation to reported cases. In addition, UpToDate MERS search volume in Jeddah and Riyadh during the outbreak periods in 2014 was significantly higher than the concurrent search volume in the negative control cities.
UpToDate search activity for specific infectious diseases also increased during outbreaks of salmonellosis, measles, dengue, West Nile virus, and influenza in Arizona, USA, and cyclosporiasis in Texas, Iowa, and Nebraska, USA. For outbreaks of salmonellosis, dengue, and measles in Arizona, UpToDate search activity increased before cases were reported or confirmed, suggesting that UpToDate search log data could be used as a complementary method for the early detection of new outbreaks. Analysis of UpToDate search logs is also a promising tool for monitoring ongoing outbreaks.