In 2016, 24 mumps cases were reported. Seventeen (71%) were classified as confirmed (tested positive by PCR), and 8 as probable (tested positive by IgM serology or were linked to another case or outbreak). Of the confirmed cases, 15 (88%) were genotyped as G which is the dominant genotype circulating in the United States for the past 10 years.
Sixteen (66%) cases were acquired in Minnesota and were not linked to outbreaks occurring elsewhere. Four cases were household contacts of a confirmed case, and 4 acquired mumps from international or domestic travel. Cases ranged in age from 16 to 53 years. Fourteen (58%) cases reported a history of receiving at least 1 dose of mumps-containing vaccine but had no documentation of those doses. Four had a documented history of 2 doses of mumps-containing vaccine; 3 cases had a documented history of 1 dose. Three reported unknown vaccination status. No case reported a previous history of mumps disease.
There was an increase in reported cases nationally in 2016, with many cases occurring in neighboring Midwestern states. The majority of Minnesota cases were indigenously acquired indicating that mumps cases are being underreported. Up to 30% of mumps infections are asymptomatic, and an additional 40-50% may have only nonspecific or primarily respiratory symptoms, making surveillance challenging. Apart from the 4 cases who acquired mumps from a close contact, no documented transmission or sustained outbreaks occurred within Minnesota.
- For up to date information see>> Mumps
- Full issue>> Annual Summary of Communicable Diseases Reported to the Minnesota Department of Health, 2016