Centers for Disease Control and Prevention (CDC) clinical case definition for mumps: illness with acute onset of unilateral or bilateral, tender, self-limited swelling of the parotid or other salivary gland, lasting ≥2 days, without other apparent cause
- In the prevaccine era, 90% of all children contracted mumps virus infection by 14 years of age.
- Incidence of this once very common disease has declined dramatically since the advent of universal childhood immunization.
- Outbreaks, however, continue to occur, and cases in the United States have ranged from several hundred to several thousand cases annually.
- Since 2014, >1,000 cases per year have been reported in the United States, with >6,000 cases reported in 2016.
- Most outbreaks have been linked to being in a close crowded environment and intense exposures, such as universities, sports teams, and close-knit religious communities.
- Outbreaks can occur in highly vaccinated communities, particularly in very close-contact settings such as college dormitories and camps.
- High vaccination rate helps limit the severity, size, and duration of mumps outbreaks.
- Two combination mumps vaccine are used:
- MMR: measles, mumps, rubella
- MMRV: measles, mumps, rubella, varicella
- A single 0.5-mL SC injection of live mumps vaccine (MMR or MMRV) is recommended at 12 to 15 months.
- A second vaccination is recommended between 4 and 6 years of age.
- The efficacy of 2 doses of vaccines is estimated at approximately 80–90%.
- Primary vaccine failure and waning vaccine-induced immunity have been reported.
- During mumps outbreaks, a third dose of vaccine may be recommended by public health authorities for targeted populations in conjunction with CDC guidance. Studies indicate no increase in adverse effects after a third vaccine dose and improved control of mumps outbreak.
- The first dose of MMR vaccine can be associated with fever and rash:
- These symptoms occur 7 to 12 days after immunization.
- Measles component is usually the culprit.
- Both MMRV and MMR vaccines, but not varicella vaccine alone, are associated with increased outpatient fever visits and seizures 5 to 12 days after vaccination in 12- to 23-month-olds, with MMRV vaccine increasing fever and seizure twice as much as the MMR + varicella vaccine.
- Vaccine should not be administered to children who are immunocompromised by disease or pharmacotherapy, as well as to pregnant women.
- If a child has recently received immune globulin (IG), administration of MMR vaccine should be delayed (for 3 to 11 months depending on the dose of immune globulin).
- Children with HIV infection who are not severely immunocompromised (age-specific CD4+ T-lymphocyte percentages of 15% or greater) should be immunized with the MMR vaccine.
- One attack of mumps (clinical or subclinical) usually confers lifelong immunity.
- Links of the MMR vaccine to autism by Andrew Wakefield in a 1998 Lancet publication have now been exposed as fraudulent, and multiple studies have documented no association between MMR vaccine and autism.
- Epidemic parotitis is caused by mumps, an RNA virus in the Paramyxoviridae family.
- Other viral causes of parotitis include Epstein-Barr virus, cytomegaloviruses, influenza, parainfluenza, and enteroviruses.
- Parotid enlargement can be an initial sign in HIV-infected children.
- Bacterial cases are usually secondary to Staphylococcus aureus (suppurative parotitis).
- Streptococci, gram-negative bacilli, and anaerobic infections are also possible.
- Rare childhood cases may be secondary to an obstructing calculus, foreign body (sesame seed), tumors, sarcoid, Sjögren syndrome, or various drugs (antihistamines, phenothiazines, iodine-containing drugs/contrast media).
- The virus is spread by contact with respiratory secretions.
- The mumps virus enters via the respiratory tract, and a viremia ultimately ensues.
- The virus spreads to many organs, including the salivary glands, gonads, pancreas, and meninges.
- Period of communicability: 7 days before to 9 days after onset of parotid swelling
- Most communicable period: 2 to 3 days before to 5 days after onset of parotid swelling
- Incubation period: 12 to 25 days after exposure (16 to 18 days most common)
- Humans are the only known host for mumps.
- Salivary adenitis
- Most common manifestation of mumps
- 1/3 of cases occur subclinically.
- Up to 35% of adolescent mumps cases are complicated by orchitis.
- Orchitis develops within 4 to 10 days of the onset of the parotid swelling.
- Sterility is uncommon.
- Aseptic meningitis
- Mild inflammation is common.
- Serious involvement is rare.
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