Mumps

Mumps is a highly contagious viral infection that is transmitted via airborne droplets. The incidence is now very low in the US because of the combined measles, mumps, and rubella (MMR) vaccine. The condition primarily affects children between the ages of five and fourteen. Classically, it manifests with parotitis, which initially occurs unilaterally, but typically progresses to involve both sides. The lateral cheek and jaw area usually show marked swelling and the ears may protrude. Other symptoms include low-grade fever, malaise, headache, and possible swelling of other salivary glands. The diagnosis of mumps is largely based on clinical findings. Many cases, however, present with nonspecific features and are not easily recognizable as mumps. If possible, diagnosis should be confirmed with laboratory tests. Treatment is symptomatic. Rare complications include orchitis, aseptic meningitis, hearing loss, and pancreatitis. Immunization offers the best protection against future exposure. Mumps is a self-limiting disease, followed by lifelong immunity. The prognosis in uncomplicated cases is very good.

• Incidence: drastically declined in the US since the introduction of the MMR vaccine ^[1][2]
• Peak age: 5–14 years of age
• Sex: ♂ = ♀ for parotitis; (however, males are three times more likely to have CNS complications) ^[3]

Epidemiological data refers to the US, unless otherwise specified.

• Pathogen: Mumps virus from the Paramyxoviridae family
• Transmission ^[4]
  • Humans are the sole host and the virus is transmitted via airborne droplets.
  • Direct contact with contaminated saliva or respiratory secretions
  • Contaminated fomites
• Infectivity ^[4][5]
  • Highly infectious
  • Affected individuals are contagious ∼ 3 days before and up to 9 days after disease onset (when the parotid gland becomes swollen).

Asymptomatic cases are also contagious.

• Nasopharyngeal entry → replication of the virus in the mucous membranes and lymph nodes → viremia and secondary infection of the salivary glands (particularly the parotid gland) → further dissemination possible (lacrimal, thyroid, and mammary glands, pancreas, testes, ovaries, CNS)

• Incubation period: 16–18 days ^[6]
• Prodrome
  • Duration: 3–4 days
  • Symptoms: low-grade fever , malaise, headache
• Classic course: inflammation of the salivary glands, particularly parotitis ; ^[5][7]
  • Duration of parotitis: at least 2 days (may persist > 10 days)
  • Symptoms
    • May initially present with local tenderness, pain, and earache
    • Unilateral swelling of the salivary gland (lateral cheek and jaw area); During the course of disease, both salivary glands are usually swollen.
    • Redness in the area of the parotid duct
    • Possible protruding ears
    • A flat, red rash that begins on the face and disseminates to the rest of the body can occur.
  • Chronic courses are rare.
• Subclinical presentation ^[6]
  • Nonspecific or predominantly respiratory symptoms
  • Asymptomatic (in 15–20% of cases) ^[4]

Laboratory tests, if available, should be conducted to confirm the suspected cases (especially if presentation is atypical or there is a mumps outbreak). ^[4][6][7]

• Pathogen detection
  • Real-time reverse transcriptase PCR (rRT-PCR) on serum or buccal or oral swab
  • Viral culture (e.g., on CSF, urine, or saliva)
• Serology: Positive serum IgM suggests recent infection and confirms the diagnosis.
• Relative lymphocytosis
• ↑ CRP, ↑ ESR
• ↑ Amylase

• Differential diagnosis of orchitis: epididymitis, testicular torsion
• Differential diagnosis of aseptic meningitis (See “Meningitis.”)

The differential diagnoses listed here are not exhaustive.

Mumps is usually self-limited with a good prognosis (unless complications arise). Treatment is mainly supportive care.

• Medication for pain and fever (e.g., acetaminophen)
• Bedrest
• Adequate fluid intake
• Avoidance of acidic foods and drinks
• Ice packs to soothe parotitis

Orchitis

• Definition: inflammation of the testis
• Epidemiology: most common complication of mumps in postpubertal male individuals (20–30% in unvaccinated postpubertal and 6–7% in vaccinated males) ^[6][8]
• Clinical features
  • Sudden onset of fever, nausea, vomiting
  • Swollen and tender affected testicle(s); primarily unilateral, although bilateral in ∼ 15% of cases
• Complications: : may lead to atrophy and, in rare cases, hypofertility

Other complications ^[4]

• Aseptic meningitis: (1–10% of cases): predominantly mild course and usually no permanent sequelae
• Encephalitis (< 1% of cases)
  • Reduced consciousness, seizures
  • Neurological deficits: cranial nerve palsy, hemiplegia, sensorineural hearing loss (rare)
• Acute pancreatitis (< 1% of cases)
  • Vomiting, nausea, upper abdominal pain
  • ↑ Lipase in addition to ↑ amylase
  • Diabetes mellitus type I (delayed complication) ^[6]
• Hearing loss (extremely rare)

The MEN of the PANamanian ORCHestra know how to throw a good PARty: MENingitis, PANncreatitis, ORCHhitis, and PARotitis are the most important complications of mumps.

We list the most important complications. The selection is not exhaustive.

• General measurements ^[4]
  • Isolate infected patients (up to 5 days after onset of symptoms).
  • Mass vaccination of susceptible people
  • Mumps is a reportable disease and all cases should be reported to the local health departments.
• Primary immunization: a live attenuated vaccine in combination with measles and rubella vaccine (i.e., MMR) and, if necessary, varicella (MMRV)
  • Recommended in all children at 12–15 months of age; see “ACIP immunization schedule” for details.
  • See also “Contraindications for live vaccines.”

Mumps vaccination during the first trimester of pregnancy may lead to embryonal death.