“…2 The incidence of ReA appears to be higher in Y pseudotuberculosis serotype O:3 outbreaks than in Y pseudotuberculosis serotype O:1 outbreaks (table 2). However, as ReA is considered less common in children than in adults, [22][23][24][25] it is possible that the different age distributions in the reported outbreaks might have influenced the observed incidences of 2 Differences in the occurrence of ReA may be explained by the varying arthritogenic potential of different Y pseudotuberculosis serotypes, differences in case ascertainment, and definitions used for Y pseudotuberculosis infection in the outbreaks, as well as different definitions of ReA (table 2). The limited number of patients in the reported outbreaks may also have a role.…”