Infectious Disease · PANCE / PANRE

Mumps

Paramyxovirus causing bilateral parotitis with fever and malaise; complications include orchitis, oophoritis, aseptic meningitis, and rare sensorineural hearing loss.

Also known as: epidemic parotitis, mumps virus, infectious parotitis

Overview

Acute viral infection caused by the mumps virus (genus Rubulavirus, family Paramyxoviridae). Classically presents with painful, bilateral parotid swelling. Transmitted by respiratory droplets and saliva.

Epidemiology

MMR has reduced US incidence dramatically, but outbreaks occur in college dormitories and tight-knit communities. Two doses of MMR are ~88% effective against mumps — lower than for measles or rubella, accounting for outbreaks in fully vaccinated young adults.

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Risk factors

Unimmunized or undervaccinated status
College and military dormitories, sports teams
International travel to endemic areas
Close-contact household and school exposure
Waning immunity in young adults

Pathophysiology

Virus enters via respiratory droplets, replicates in the nasopharynx and regional lymph nodes, and disseminates by viremia to salivary glands, gonads, pancreas, and CNS. Glandular swelling reflects ductal epithelial necrosis and interstitial edema.

Clinical presentation

Symptoms

Prodrome (1-2 days): low-grade fever, malaise, anorexia, headache, earache
Parotid swelling: typically bilateral (70-80%), tender, with displacement of the earlobe outward and upward; peaks at 2-3 days
Submandibular and sublingual glands also affected in some cases
Orchitis: testicular pain and swelling in 15-30% of post-pubertal males, 4-8 days after parotitis
Aseptic meningitis: headache, photophobia, neck stiffness

Signs / physical exam

Edema obliterating the angle of the jaw
Erythematous Stensen duct orifice without purulence
Unilateral or bilateral testicular tenderness with overlying erythema
Mild meningismus

Classic findings

Bilateral parotid swelling in an unvaccinated adolescent with low-grade fever.

Differential diagnosis

Bacterial parotitis (S. aureus) — Unilateral, exquisitely tender, purulent expression from Stensen duct, elderly/dehydrated
Sialolithiasis — Mealtime swelling and pain, stone on imaging or massage
HIV-associated lymphoepithelial cysts — Painless, bilateral, multicystic on imaging
Sjögren syndrome — Chronic, dry eyes/mouth, autoantibodies
Lymphoma of parotid — Chronic, painless mass, B symptoms
Tumor (pleomorphic adenoma, Warthin) — Slowly enlarging unilateral mass, often discovered incidentally

Diagnostic workup

Diagnostic criteria

Clinical presentation plus positive RT-PCR or seroconversion. Report to public health (nationally notifiable).

Labs

Mumps IgM and IgG (paired sera) — IgM may be falsely negative in vaccinated patients
RT-PCR on buccal swab from the Stensen duct (preferred; collect within 3 days of parotitis onset)
Amylase often elevated (parotid source, not pancreatic) — distinguish with lipase
CBC: leukopenia with relative lymphocytosis
CSF in suspected meningitis: lymphocytic pleocytosis, normal glucose

Imaging

Not routinely required; ultrasound or CT of parotid only if abscess or stone suspected
Scrotal ultrasound to confirm orchitis and exclude torsion

Diagnostic algorithm

flowchart TD
  A[Bilateral parotid swelling<br/>+ low-grade fever] --> B[Mumps RT-PCR<br/>buccal swab + IgM/IgG]
  B --> C{Confirmed mumps}
  C --> D[Droplet isolation 5 d<br/>Supportive care]
  D --> E{Complications?}
  E -->|Orchitis| F[NSAIDs, support, ice]
  E -->|Aseptic meningitis| G[LP, supportive]
  E -->|Hearing loss| H[Audiology referral]
  C --> I[Public health report<br/>+ Outbreak: third MMR dose]

Mumps clinical pathway from presentation through complication management.

Treatment

First-line

Supportive care: hydration, antipyretics (acetaminophen, ibuprofen), warm or cold compresses, soft diet
Avoid sour foods (stimulate painful salivation)
Isolation (droplet precautions) for 5 days after parotitis onset
MMR vaccine (live, 2-dose schedule) is the primary prevention strategy — first dose at 12-15 months, second at 4-6 years

Mumps orchitis

Bed rest, scrotal support, ice packs
NSAIDs
Corticosteroids and interferon are not proven; do not prevent atrophy

Outbreak control

Third dose of MMR for individuals in close-contact outbreak settings (ACIP 2018)
Isolation of cases for 5 days from parotitis onset

Second-line / adjunct

No antiviral therapy proven effective
Treat bacterial superinfection if suspected

Complications

Orchitis (15-30% of post-pubertal males) — testicular atrophy in half, but sterility uncommon
Oophoritis (5% of post-pubertal women)
Aseptic meningitis (1-10%)
Encephalitis (rare, more severe)
Sensorineural deafness (often unilateral, sometimes permanent)
Pancreatitis
First-trimester miscarriage (no link to congenital defects)

PANCE pearls

Two doses of MMR are required, but vaccine effectiveness against mumps is only ~88% — outbreaks happen in vaccinated populations.
Earlobe displacement upward and outward by parotid swelling is the classic exam finding.
Buccal swab RT-PCR within 3 days of parotitis is the most sensitive diagnostic.
Mumps is a leading viral cause of unilateral sensorineural hearing loss in children.
Lipase distinguishes pancreatitis from parotid amylase elevation.

References

ACIP 2018 — Recommendation of the ACIP for Use of a Third Dose of Mumps Virus-Containing Vaccine in Persons at Increased Risk for Mumps During an Outbreak (Marin et al., MMWR 2018)
AAP Red Book — American Academy of Pediatrics Red Book — Mumps chapter
CDC — CDC Mumps Surveillance and Outbreak Resources

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