Spearman’s rho values for the 18 top ranked notifiable diseases for the period 2009–13. The table only contains the search term with the highest degree of correlation for each disease; see Additional file 1 for a full list of diseases, search terms and correlation coefficients. The column label in bold indicates the Google Trends data used and subheadings in italics indicate the disease notification data used. Case numbers are National totals for the period 2009–13. Shading denoted statistical significance (one-tailed, Bonferroni corrected) at 0.0001 (red), 0.001 (orange), 0.01 (yellow) and 0.05 (green) levels. For disease grouping, BB: Blood-borne diseases; GI: Gastrointestinal diseases; Other; Other bacterial diseases; QD; Quarantinable diseases; STI: Sexually Transmissible Infections; VBD: Vector-borne Diseases; VPD: Vaccine preventable diseases; Zoo: Zoonoses.