Fig. 8

Additional scatterplots of incidence 39 global studies [15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53] reporting incidence, individually represented as circles with size proportional to sample size, are visualized. a 2 cohort studies [47, 49] were removed from the global latitudinal selection before re-plotting with remaining 37 figures. 95% confidence intervals (CIs) and line of regression are shown. b 4 community-based studies [21, 24, 42, 49] were removed from the global latitudinal selection before re-plotting with remaining 35 figures. 95% CIs and line of regression shown. c Global incidence plotted against time, defined here as the midpoint of observation period. Studies are represented as circles proportional to sample size. 95% CIs and line of regression are shown. The observation period of all incidence studies extended 1957 to 2014 with midpoints ranging from 1961 to 2013. Corresponding univariate meta-regression analysis demonstrated no effect of time on incidence globally (p = 0.07)