Brief report: update: mumps activity--United States, January 1-October 7, 2006.

During January 1-October 7, 2006, a total of 45 states and the District of Columbia reported 5,783 confirmed or probable mumps cases to CDC. This includes 2,597 cases previously reported by 11 states during January 1-April 29, 2006. This report summarizes the epidemiology of mumps cases in the United States during 2006. With low levels of reported mumps continuing, health-care workers should remain alert to suspected mumps, conduct appropriate laboratory testing, and use every opportunity to ensure adequate immunity, particularly among populations at high risk for mumps.