Fig. 3: O-type and H-type diversity.

a A bar chart showing the frequency of the different O-types. b A bar chart showing the proportion of isolates per year that had different O-types. The colours are the same as those represented in (a). c A bar chart showing the frequency of the different H-types. Where an isolate had more than one H-type gene, this was counted twice. d A bar chart showing the proportion of isolates per year that had different H-types. The colours are the same as those represented in (c).