The money quote:
The state Health Department reports at least 45 children in religious communities in Monsey and Spring Valley have come down with the mumps… Health officials say the disease shows no signs of spreading beyond the religious communities.
So what happened? It appears that Hasidic Jews who concentrate in the affected areas are reluctant to vaccinate their children. E.G.:
Measles is one of those childhood diseases that, like polio, has been all but eradicated in the United States, thanks to decades of aggressive government vaccination efforts. But New York’s ultra-Orthodox neighborhoods are suffering through their second outbreak in as many years—the direct result of large numbers of unvaccinated children being exposed to regular visitors from the far-flung corners of the Hasidic world, where measles still exists.
Health officials say that ultra-Orthodox parents in Brooklyn are as susceptible as their crunchier counterparts to the belief that there may be a causal link between the measles-mumps-rubella vaccine and autism. (Public health officials say there is no evidence to support the claim.) The kids of most skeptics serve as free riders, staying clear of the infection because most other children they come in contact with are vaccinated and safe. But the tendency of Hasidic parents to wait far beyond the recommended 12-month vaccination deadline produces a large pool of potential victims for viruses trafficked by unvaccinated—and frequently visiting—kids from Israel and Europe. “Herd immunity can’t protect you if you’ve got a case in there and a large pocket of unvaccinated people,” said Jane Seward, deputy director of the division of viral diseases of the Centers for Disease Control in Atlanta. “It just ignites.”