Mumps, 2009

During 2009, 6 cases of mumps (0.13 per 100,000) were reported. All 6 cases were laboratory confirmed, including 1 (17%) case confirmed by both positive mumps IgM serology and a demonstrated rise in mumps IgG between acute and convalescent serologic specimens, and 5 (83%) cases confirmed by mumps IgM serology only. None of the 6 cases was epidemiologically linked to a source case, demonstrating that asymptomatic infections are occurring, and suggesting that mumps is under-diagnosed. Cases ranged in age from 25 to 70 years. All cases occurred in persons older than 21 years of age; 3 (50%) cases occurred in persons 22 through 33 years of age; 1 (17%) case occurred in persons 34 through 49 years of age; and 2 (33%) cases occurred persons 50 years and older.

No cases had a documented history of 2 doses of mumps-containing vaccine; 1 case (17%) had a documented history of 1 dose. Two cases (33%) reported a history of receiving 1 dose of mumps-containing vaccine but these reports were not verified. No cases reported a previous history of mumps disease; and 3 (50%) had unknown history of disease as well as unknown vaccination status, 1 of whom was born before 1957 and 2 of whom were born after 1957.

Mumps surveillance is complicated by nonspecific clinical presentation in nearly half of cases, asymptomatic infections in an estimated 20% of cases, and suboptimal sensitivity and specificity of serologic testing. Mumps should not be ruled out solely on the basis of negative laboratory results. Providers are advised to test for other causes of sporadic parotitis including parainfluenza virus types 1 and 3, Epstein-Barr virus, influenza A virus, coxsackie A virus, echovirus, lymphocytic choriomeningitis virus, human immunodeficiency virus, and other noninfectious causes such as drugs, tumors, immunologic diseases, and obstruction of the salivary duct.

• For up to date information see>> Mumps
• Full issue>> Annual Summary of Communicable Diseases Reported to the Minnesota Department of Health, 2009