Mumps, 2018

In 2018, 13 mumps cases were reported. Eleven (85%) were classified as confirmed (tested positive by PCR), and 2 (15%) as probable (tested positive by IgM serology or were linked to another case or outbreak). All of the confirmed cases were genotyped as G, which is the dominant genotype circulating in the United States since 2006.

Two (15%) cases reported a history of receiving at least 1 dose of mumps-containing vaccine but had no documentation of those doses. Four (31%) cases had a documented history of receiving 1 or 2 doses of mumps-containing vaccine. Two (15%) cases were unvaccinated, and 5 (38%) reported unknown vaccination status. No case reported a previous history of mumps disease.

Eight (62%) cases were acquired in Minnesota and were not linked to outbreaks occurring elsewhere, and 5 (38%) acquired mumps from international travel. The median age of cases was 32 years (range 20 to 85). Nine cases (69%) occurred in persons 18-49 years, and 4 (31%) occurred in persons ≥50 years of age. Twelve cases (92%) experienced parotitis, and 5 (38%) reported orchitis. One unvaccinated adult was hospitalized for 1 day with fever, arthralgia, and bilateral orchitis and recovered without complications.

Mumps surveillance is complicated by nonspecific clinical presentation in nearly half of cases, asymptomatic infections in an estimated 30% of cases, and suboptimal sensitivity and specificity of serologic testing. A number of viruses can cause sporadic parotitis including parainfluenza virus types 1 and 3, influenza A virus, human herpes virus 6, enterovirus, Epstein- Barr, lymphocytic choriomeningitis virus, bocavirus, and human immunodeficiency virus. Acute bacterial parotitis may present with unilateral swelling. Noninfectious causes include drugs, tumors, and immunologic diseases.

• For up to date information see>> Mumps
• Full issue>> Annual Summary of Communicable Diseases Reported to the Minnesota Department of Health, 2018