Isn't mumps a disease that included in childhood immunizations? Or have "they" decided that the vaccine is no longer needed becasue of so few cases or becasue of the anti-vaccine crowed?
Yes, it's the MMR immunization (measles, mumps, rubella). I think it's typically required for school but some parents don't have their kids immunized. Apparently this strain of mumps was imported from England.
The vaccination frequently attenuates over the years. The idea is that you get a critical mass of kids vaccinated and this breaks the transmission vectors so that even unvaccinated people or people whose immunity has waned with age don't have much to worry about. But, if there's an outbreak anyhow, then you've got to revaccinate.
I somehow managed to contract a freak case of mumps back in 1989. They didn't have any other reports of it in the area, but I somehow got it, and I had had all the childhood vaccinations.