Infectious Disease · PANCE / PANRE

Mumps

Written & clinically reviewed by Ryan Busch, PA-C · Updated August 2026 · Report an error

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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Question 1Infectious DiseaseEasy
A 17-year-old male college freshman presents with 3 days of painful bilateral cheek swelling that worsened over the first 2 days, accompanied by low-grade fever, malaise, and earache. He recently moved into a crowded dormitory and is unsure whether he completed his childhood vaccinations. On exam, both parotid regions are tender and swollen, with the swelling pushing each earlobe outward and upward and obliterating the angle of the jaw. The Stensen duct orifices are erythematous but express no pus. Which of the following is the most likely diagnosis?
  • AMumps
  • BBacterial parotitis
  • CSialolithiasis
  • DPleomorphic adenoma
Reveal answer & full explanation
Correct answer: A — Mumps
  • AMumps✓
  • BBacterial parotitis
  • CSialolithiasis
  • DPleomorphic adenoma

Why Mumps is correct

  • Acute, tender, bilateral parotid swelling with the earlobe displaced upward and outward in an undervaccinated young adult living in a crowded dormitory is the classic mumps presentation.
  • A viral prodrome (low-grade fever, malaise, earache) followed by parotid swelling that peaks at 2-3 days, plus an erythematous Stensen duct orifice WITHOUT purulent discharge, points to mumps rather than a bacterial or obstructive cause.
  • Two MMR doses are only about 88% effective against mumps, so outbreaks still occur in college and military dormitories; diagnosis is confirmed with buccal-swab RT-PCR collected within 3 days of parotitis onset, and mumps is nationally notifiable.

Why the others are wrong

  • Bacterial parotitis is typically unilateral and exquisitely tender with purulent material expressible from the Stensen duct, usually in elderly or dehydrated patients; the bilateral involvement and absence of pus argue against it.
  • Sialolithiasis causes mealtime (postprandial) gland swelling and pain from ductal stone obstruction and is usually unilateral; it lacks the viral prodrome and bilateral parotid involvement seen here.
  • Pleomorphic adenoma is a benign salivary gland tumor that presents as a slowly enlarging, painless, unilateral mass rather than an acute febrile bilateral swelling.
Question 2Infectious DiseaseMedium
A 19-year-old college freshman presents with 2 days of bilateral cheek swelling, low-grade fever, and pain when chewing. He lives in a crowded dormitory and is unsure whether he completed his childhood vaccine series. On exam, both parotid glands are tender and swollen, displacing the earlobes upward and outward, and the angle of the jaw is obscured. The orifice of the Stensen duct is erythematous without purulent drainage. His symptoms began roughly 48 hours ago. Which of the following is the most appropriate next diagnostic test?
  • ASerum mumps IgM antibody titer
  • BContrast-enhanced CT of the neck
  • CSerum amylase and lipase levels
  • DBuccal swab for mumps RT-PCR
Reveal answer & full explanation
Correct answer: D — Buccal swab for mumps RT-PCR
  • ASerum mumps IgM antibody titer
  • BContrast-enhanced CT of the neck
  • CSerum amylase and lipase levels
  • DBuccal swab for mumps RT-PCR✓

Why Buccal swab for mumps RT-PCR is correct

  • This vignette is classic acute mumps: bilateral tender parotitis with upward-and-outward earlobe displacement in an undervaccinated young adult in a dormitory outbreak setting.
  • A buccal (Stensen duct) swab for RT-PCR is the most sensitive confirmatory test and is the preferred study when collected within 3 days of parotitis onset; this patient is within that window.
  • Mumps is nationally notifiable, so laboratory confirmation guides public health reporting and outbreak control.

Why the others are wrong

  • Serum mumps IgM antibody titer is a useful adjunct but is less sensitive than early PCR and is frequently falsely negative in previously vaccinated patients, so it is not the preferred confirmatory test in an outbreak with classic findings.
  • Serum amylase and lipase levels can show an elevated amylase from a parotid source, but that finding does not confirm mumps; lipase is used to exclude pancreatitis, not to establish the diagnosis.
  • Contrast-enhanced CT of the neck is not routinely required and is reserved for suspected abscess or sialolithiasis; the bilateral inflammatory swelling without fluctuance or purulence does not suggest those.
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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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Differentials & related conditions

Salivary Gland Disorders (Sialadenitis, Sialolithiasis, Parotitis)Sjögren Syndrome

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