Increase in Mumps Cases Among Young Adults in Orange County
August 23, 2018
Orange County Health Care Agency has received five reports of mumps cases among young adults since June 1, 2018. The cases ranged in age from 18-22, three of five were male. Two reported histories of travel to regions where mumps is endemic or an outbreak is occurring, one had close contact with a mumps case. None attended school during their potential exposure period. Four of five cases self-reported having received two doses of MMR (measles, mumps, rubella) vaccine in the past. Orange County has had eight cases of mumps reported since the start of the year, including four cases who have no history of travel or known mumps exposure and apparently acquired infection locally.
  • Providers should consider the diagnosis of mumps in patients with an appropriate clinical presentation, particularly in young adults, those with a history of international travel, or exposure to a known mumps case. Notify the Orange County Health Care Agency Epidemiology Program immediately at 714-834-8180 with any suspect cases.
  • Providers are encouraged to ask patients with parotitis whether they have had contact with other cases of mumps or parotitis. Mumps should be considered in all patients with parotitis, but testing is particularly important when multiple cases of parotitis are identified in a school, family, work site, or other social group.
  • Mumps’ most characteristic symptom is parotid swelling. Parotitis is unilateral at first but eventually becomes bilateral in 70% of cases. Parotitis can initially manifest as earache and tenderness on palpation of the angle of the jaw. Symptoms generally resolve over 7-10 days.
  • A nonspecific prodrome often occurs 1-2 days before the onset of parotid swelling, and can include muscle aches, loss of appetite, malaise, headache, or fever.
  • Complications include orchitis (testicular swelling), which occurs in 14-35% of postpubertal males, and aseptic meningitis, which is found in 1-10% of cases.
  • The incubation period ranges from 12 to 25 days.
  • Treatment is supportive.
Laboratory Testing:
  • The preferred method of diagnosis is mumps polymerase chain reaction (PCR) testing of a buccal swab specimen. Collection of a buccal specimen within 1 to 3 days of parotitis onset is optimal, but virus may be detected for up to 9 days after parotitis onset. The Orange County Health Care Agency Laboratory can assist with performing mumps PCR testing.
  • Testing can also include serum mumps IgM and IgG. However, the mumps IgM response may be absent in immunized patients, and patients with detectable mumps IgG can still develop infection.
  • Detailed descriptions of specimen collection procedures can be found at:
Infection Control:
  • Mumps virus is transmitted by direct exposure to respiratory secretions of infected persons.
  • Infectiousness is highest from 2 days before until 5 days after onset of parotitis. Persons with mumps should stay home from work, school and other activities until at least 5 days after symptom onset.
  • Healthcare providers should use droplet and standard precautions when caring for suspect or confirmed cases.
  • Healthcare workers should have two documented MMR doses or documented mumps immunity.
  • Mumps vaccine is given as part of the Measles, Mumps and Rubella (MMR) vaccine.
  • All children are recommended to receive a first MMR at 12-15 months and a second MMR at 4-6 years of age.
  • All adults without evidence of immunity to measles, mumps, and rubella should have at least one dose of MMR. Certain high risk groups should have two MMR doses, including healthcare professionals, international travelers and students at post-high school educational institutions.
  • The CDC estimates an effectiveness of two MMR doses for preventing mumps of 88%.
  • Vaccination does not provide post-exposure prophylaxis for mumps, but should prevent illness after future exposures. 
  • Breakthrough infection can occur despite vaccination, and most cases seen in college outbreaks have occurred in fully vaccinated patients. However, high vaccination coverage can help to limit the spread, duration, and magnitude of mumps outbreaks.
Contact Information:
If you have any questions or concerns please contact the Epidemiology and Assessment Program at (714) 834-8180.
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