Mumps surveillance--United States, 1988-1993.

Problem/condition: CDC monitors the incidence of mumps in the United States through the passive reporting of cases to its National Notifiable Disease Surveillance System (NNDSS).
Reporting Period Covered: 1988-1993.
Description of System: Weekly reports to the NNDSS from 48 states and the District of Columbia were used to calculate incidence rates for mumps. State immunization requirements were obtained from the U.S. Department of Health and Human Services.
Results: After the licensure of mumps vaccine in the United States in December 1967 and the subsequent introduction of state immunization laws in an increasing number of states, the reported incidence of mumps decreased substantially. The 1,692 cases of mumps reported for 1993 represent the lowest number of cases ever reported to NNDSS and a 99% decrease from the 152,209 cases reported for 1968. During 1988-1993, most cases occurred in children 5-14 years of age (52%) and in persons > or = 15 years of age (36%). Although the incidence decreased in all age groups, the largest decreases (> 50% reduction in incidence rate per 100,000 population) occurred in persons > or = 10 years of age. Overall, the incidence of mumps was lowest in states that had comprehensive school immunization laws requiring mumps vaccination and highest in states that did not have such requirements.
Interpretation: Because of the extensive use of mumps vaccine and the increased number of states that had enacted mumps immunization laws, the number of reported mumps cases decreased further since the marked decline that began during the early 1970s. The earlier shift in incidence from children of school ages to older persons that was noted during 1985-1988 continued until 1992, when the proportion of cases occurring in children of school ages increased and exceeded the proportions occurring in other age groups.
Actions Taken: All health-care providers are encouraged to a) report mumps cases to their local and state health departments for transmission to NNDSS and b) enact school immunization laws requiring mumps vaccination.