Mumps, 2008

During 2008, 9 cases of mumps (0.2 per 100,000) were reported. All 9 cases were laboratory confirmed, including 1 (11%) case confirmed by both positive mumps IgM serology and a demonstrated rise in mumps IgG between acute and convalescent serologic specimens, and 8 (89%) cases confirmed by mumps IgM serology only. None of the 9 total cases were epidemiologically linked to a source case, demonstrating that asymptomatic infections are occurring, and suggesting that mumps is under-diagnosed.

Case-patients ranged in age from 11 to 52 years. Six (67%) cases occurred in persons older than 21 years of age; 2 (22%) cases occurred in persons 22 through 33 years of age; 4 (44%) cases occurred in persons 34 through 49 years of age; and 1 (11%) case occurred in a person 50 years and older.

Two (22%) case-patients had a documented history of two doses of mumps-containing vaccine. The other seven (78%) case-patients had no documented history of vaccination for mumps. Of these seven case-patients, two (29%) reported a history of mumps; two (29%) reported a history of receiving two doses of mumps-containing vaccine but were not verified; one (14%) reported a history of receiving one dose of mumps-containing vaccine but was not verified; and two (29%) had unknown history of disease and vaccination, one of whom was born before 1957 and one of whom was 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.

The CDC released new guidance in April 2008 which advises that mumps infections 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, 2008