Examination of outbreaks within categories of setting, identification of the index case, and clinical characteristics provided additional insights. By reviewing original publications, we were able to categorize and analyze many outbreaks by setting. For example, were able to review the original publications for eight outbreaks documented by the WHO [25, 26, 28, [33] [34] [35] [36] [37] as well as, identify thirteen additional outbreaks [20, 27, [29] [30] [31] [38] [39] [40] [41] . Several of these outbreaks also had epidemiologically distinct components, resulting in 51 effective outbreaks for analysis.