Two boys study together at a Chicago yeshiva in 2009. Public health officials say this type of close physical contact caused a mumps outbreak to spread throughout several orthodox Jewish communities in and around New York City. M. Spencer Green/AP hide caption

itoggle caption M. Spencer Green/AP

The Passover Seder plate with symbolic foods (clockwise, from top center): horseradish; a shank bone; a mixture of fruit, wine and nuts called haroset; lettuce, parsley and an egg. Dan Goodman/AP hide caption

itoggle caption Dan Goodman/AP