Mumps   
Annual Summary of Reportable Diseases

• In 2023, two unrelated cases of mumps were confirmed in Minnesota.  
• No outbreaks of mumps were reported in Minnesota.
• Nationally, mumps case counts were low in 2023, and no significant outbreaks occurred. 

Two mumps cases were identified in 2023 in Minnesota and laboratory confirmed PCR positive. One of the cases was genotyped as D, and the other case was sequenced but failed to be successfully genotyped. Two cases reported receiving at least one dose of mumps vaccine (MMR); however, only one case had 2 doses documented with dates.  

One case acquired mumps in Minnesota from exposure to a relative with recent international travel and mumps compatible symptoms, and one acquired mumps from direct international travel. Both cases were in adult females, one residing in Rice County, the other in Hennepin County. Both experienced parotitis, and neither were hospitalized. 

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Mumps is a viral disease, which typically spreads from person to person via prolonged and close contact with infected persons. In 2022, seven mumps cases were reported. One (14%) was classified as confirmed (tested positive by PCR) but failed to be successfully genotyped. Six cases (86%) were classified as probable (tested positive by IgM serology). Five (71%) cases reported receiving at least one dose of mumps vaccine (MMR). Two (29%) cases were unvaccinated. No case reported a previous history of mumps disease.

Six (86%) cases acquired mumps in Minnesota and were not linked to outbreaks occurring elsewhere, and one (14%) acquired mumps from international travel. The median age of cases was 28 years (range 8 to 42). All 7 cases experienced parotitis. None were hospitalized.

Mumps surveillance is complicated by nonspecific clinical presentation in nearly half of cases, asymptomatic infections in an estimated 30% of cases, improper laboratory test ordering, and suboptimal sensitivity and specificity of serologic testing. Several 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.

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No mumps cases were reported in 2021.

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In 2020, 2 mumps cases were reported. The two cases reported were classified as probable (tested positive by IgM serology). The first case occurred in an individual with recent travel to Mexico. The second case had an unknown source. One case was 18-49 years, and the second case was ≥50 years of age. Both cases reported not knowing their vaccination status, and no vaccination records could be located. Both cases reported parotitis and one reported orchitis. Neither case was hospitalized.

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.

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In 2019, 11 mumps cases were reported. Nine were classified as confirmed (tested positive by PCR), and 2 as probable (tested positive by IgM serology or were linked to another case or outbreak). Two were genotyped as K, a common genotype circulating in mainland southeast Asia. The remaining confirmed cases were genotyped as G, which is the dominant genotype circulating in the United States since 2006. Eight cases had a documented history of receiving at least 1 dose of mumps-containing vaccine, 1 was unvaccinated, and 2 reported unknown vaccination status. No case reported a previous history of mumps disease.

Seven cases occurred in a county jail housing U.S. Immigration and Customs Enforcement detainees linked to larger national outbreak involving 898 cases in 19 states. Two cases were acquired in Minnesota and were not linked to outbreaks occurring elsewhere, 1 acquired mumps from domestic travel, and 1 from international travel. The median age of cases was 27 years (range 3 to 36 years). Ten cases occurred in persons 18-49 years, and 1 was <18 years of age. Ten experienced parotitis, and 1 reported orchitis.

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 virus, 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

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

• Archive of Annual Summary of Communicable Diseases Reported to the Minnesota Department of Health
  Archive of past summaries (years prior to 2023 are available as PDFs).