The year isn’t quite over yet, but we’ve already had 4,258 cases of mumps in the U.S., more than any year since 2006, when we also experienced a dramatic spike in cases. As the chart here shows, before 2006 we only saw a couple of hundred cases per year, but the numbers have been trending higher since then. After two years with about 1,200 cases each, this year looks to quadruple last year’s total when the final numbers come in.