Inverse distance weighting (IDW) interpolation map of PI*SZ prevalence in Europe. Prevalence is represented by a colour-gradient “red (high)–blue (low)” scale; areas with population density below 1 inhabitant per km2 appear in white. The highest PI*SZ prevalence is in Portugal (1:205), followed by Spain (1:278), Latvia (1:354), France (1:413), Republic of Ireland (1:424), Belgium (1:551), the Netherlands (1:617), and UK (1:900), and it is over 1 per 1000 in the remaining European countries, reaching the minimum prevalence of almost 1:25 000 in Russia. By individual countries, the highest number of PI*SZ are in Spain (174 822), followed by France (161 680), UK (73 973), Italy (64 137), Germany (60 396) and Portugal (52 836). Pi*SZ numbers in other countries are very variable, but always much lower than in the aforementioned. Figure and text adapted from [19] with permission.