SEATTLE -- Skagit County health officials have identified ten cases of mumps in the county. Half the cases involve students in the Mount Vernon School District.

No mumps cases have been found in other districts, but health officials say the mumps virus is extremely contagious.

Officials say the measles-mumps-rubella vaccination is the most effective weapon against mumps. People who have not had two mumps vaccinations are nine times more likely to contract the illness.