Assessing cyber-user awareness of an emerging infectious disease: evidence from human infections with avian influenza A H7N9 in Zhejiang, China

Objectives: The aim of this study was to assess cyber-user awareness of human infections with avian influenza A H7N9 in Zhejiang, China. Methods: Daily Baidu index values were compared for different keywords, different periods (epidemic and non-epidemic), different levels of epidemic publicity (whether new cases were publicized), and different cities (divided into high, medium, low, and zero groups according to the number of cases). Furthermore, the correlation between the daily Baidu index values and the daily number of new cases was analyzed. Results: Three epidemic periods (periods A/C/E) and three non-epidemic periods (periods B/D/F) were identified from April 2013 to May 2015 according to the curves of daily new cases. Each epidemic period was followed by a non-epidemic period. Baidu index values using 'H7N9' as a keyword were higher than the values using the keyword (avian influenza in Chinese) in earlier periods, but the situation reversed in later periods. Index values for 'H7N9' in the epidemic periods were higher than in the non-epidemic periods. In the first epidemic period (period A), the Baidu index values for 'H7N9' showed no difference between the different levels of epidemic publicity and had no correlation with the daily number of new cases. The index values in cities without reported cases showed no difference from the values recorded in the medium and low groups. However, a difference and a correlation were found in a later epidemic period. Conclusions: The Baidu index would be a useful tool for assessing cyber-user awareness of an emerging infectious disease. (C) 2015 The Authors. Published by Elsevier Ltd on behalf of International Society for Infectious Diseases.