Mumps is an acute, vaccine-preventable viral illness caused by a paramyxovirus (single-stranded RNA virus, genus Rubulavirus), transmitted via respiratory droplets and saliva. [1-2] The pathognomonic finding is nonsuppurative parotitis, though 15–27% of infections are asymptomatic. [1][3] Despite high vaccination coverage, outbreaks continue to occur, particularly in close-contact settings such as universities and congregate living. [4-5]
1. History
- Exposure history: Contact with a known mumps case, travel to endemic regions, congregate living (dormitories, barracks, shelters, jails) [2-3][6]
- Vaccination status: Number of MMR doses and timing of last dose; vaccine efficacy ~88% with 2 doses, waning immunity over time [4][7]
- Prodrome: Low-grade fever, headache, myalgias, malaise, and anorexia typically precede parotitis by 1–2 days [3]
- Parotitis characterization: Unilateral vs. bilateral, onset timing, duration (typically ≥2 days), pain with chewing or swallowing [1][8]
- Incubation period: Average 16–18 days (range 12–25 days) [1][9]
- Important negatives: Purulent drainage from Stensen's duct (suggests bacterial sialadenitis, not mumps), recurrent episodes (consider sialolithiasis, juvenile recurrent parotitis), painless mass (consider neoplasm) [10]
2. Alarm Features
- Severe testicular pain/swelling (orchitis) — most common serious complication in postpubertal males (3–10% in vaccine era) [1][5]
- Meningeal signs: Headache, neck stiffness, vomiting, photophobia — meningitis occurs in 1–10% of infections [8]
- Seizures, altered consciousness, focal neurological deficits — suggest encephalitis (0.1%), which carries ~1.5% mortality [8]
- Severe abdominal/epigastric pain — consider pancreatitis (~4% prevaccine era, <1% vaccine era) [1]
- Sudden hearing loss — can be unilateral, permanent; estimated 1 in 20,000 cases [8]
- Severe dehydration from inability to eat/drink due to parotid pain
3. Medications
- No antiviral therapy exists — treatment is entirely supportive [2]
- Analgesics/antipyretics: Acetaminophen or NSAIDs for pain and fever
- NSAIDs (e.g., ibuprofen) preferred for orchitis-related pain and inflammation
- Avoid aspirin in children (Reye syndrome risk)
- Drug-induced parotitis is a differential consideration — phenothiazines, thiouracil, iodides, and phenylbutazone can cause parotid swelling [8]
4. Diet
- Avoid sour, acidic, or citrus foods/drinks — stimulate salivary flow and worsen parotid pain
- Soft, bland diet recommended during acute parotitis
- Adequate hydration is essential, especially with fever or poor oral intake
- Avoid hard-to-chew foods during the acute phase
5. Review of Systems
- HEENT: Jaw/ear pain, difficulty opening mouth, hearing changes, sore throat
- Neurological: Headache, neck stiffness, altered mental status, ataxia, seizures
- GU (males): Testicular pain/swelling (orchitis), typically onset ~4–8 days after parotitis
- GU (females): Lower abdominal/pelvic pain (oophoritis ~5% prevaccine, ≤1% vaccine era) [1]
- GI: Epigastric pain, nausea, vomiting (pancreatitis)
- Breast: Tenderness/swelling (mastitis in postpubertal females) [1]
- Constitutional: Fever, malaise, anorexia, myalgias
6. Collateral History and Family History
- Outbreak context: Known cases at school, workplace, or community; recent travel to endemic areas [3-4]
- Household contacts: Vaccination status of close contacts; immunocompromised household members
- Immigration/travel history: Outbreaks linked to migrant populations and international travel [6]
- Family history is generally not contributory, as mumps is an infectious rather than hereditary condition
7. Risk Factors
- Incomplete or absent MMR vaccination [2][4]
- Waning vaccine-induced immunity — risk increases with time since last MMR dose [4]
- Close-contact/congregate settings: College dormitories, military barracks, detention facilities, close-knit communities [5-6]
- Age: Young adults (median outbreak age ~21 years); complications more frequent in adults than children [5][11]
- Male sex: Higher complication rate, primarily driven by orchitis [11-12]
- International travel to endemic regions [3]
- Immunocompromised status [2]
The following figure from the 2006 U.S. resurgence demonstrates the age- and sex-dependent complication rates:
8. Differential Diagnosis
- Other viral parotitis: EBV (most common mimic, ~7–20% of mumps-negative parotitis), parainfluenza viruses (types 1–3), influenza A (especially H3N2), adenovirus, HHV-6B, HIV, coxsackievirus, parvovirus B19 [8][13-15]
- Acute suppurative sialadenitis: Bacterial (S. aureus), presents with unilateral erythema, tenderness, and purulent discharge from Stensen's duct; mortality up to 40% if untreated [10]
- Sialolithiasis: Recurrent periprandial swelling; most common cause of salivary gland swelling overall [10]
- Sjögren syndrome / IgG4-related disease: Chronic bilateral parotid swelling, xerostomia [10]
- Salivary gland neoplasm: Painless, slow-growing mass [10]
- Juvenile recurrent parotitis: Recurrent unilateral episodes in children, may resolve at puberty [10]
- Drug-induced parotitis: Phenothiazines, iodides, thiouracil [8]
- Peritonsillar/parapharyngeal abscess: Can mimic parotid swelling
Key pearl: In non-outbreak settings, only ~9% of clinically diagnosed mumps cases may be confirmed by laboratory testing; laboratory confirmation is essential. [8][16]
9. Past Medical History
- Prior MMR vaccination (number of doses, dates)
- Previous mumps infection (confers lifelong immunity)
- Immunocompromising conditions (HIV, transplant, chemotherapy)
- History of recurrent parotitis or salivary gland disease
- Pregnancy status — mumps in the first trimester may increase spontaneous abortion risk [17]
10. Physical Exam
- Vital signs: Low-grade fever typical; high fever suggests complication (meningitis, orchitis)
- Parotid glands: Unilateral or bilateral, tender, nonsuppurative swelling; ear lobe displaced upward and outward; obscures angle of mandible
- Stensen's duct: Erythematous and edematous orifice; no purulence on expression (purulence = bacterial sialadenitis) [3][10]
- Submandibular/sublingual glands: May also be involved
- Neck: Assess for lymphadenopathy, peritonsillar fullness
- Neurological: Meningeal signs (Brudzinski, Kernig), mental status, cranial nerves (facial nerve palsy reported rarely) [8][11]
- Genitourinary (males): Testicular exam — swelling, tenderness, erythema of scrotal skin (orchitis)
- Abdomen: Epigastric tenderness (pancreatitis)
11. Lab Studies
- RT-PCR (buccal/parotid duct swab): Preferred diagnostic test — highest sensitivity (90% in one outbreak study), detectable from before parotitis onset through 5–9 days post-onset. Massage parotid gland for 30 seconds before swabbing Stensen's duct. [7][18]
- Mumps IgM serology: Supportive but less sensitive, especially in previously vaccinated individuals (sensitivity ~34–43% in vaccinated vs. ~64% in unvaccinated). Optimum collection 7–10 days after symptom onset. [7-8][18]
- Mumps IgG (acute and convalescent): 4-fold rise confirms infection; acute sera at onset, convalescent at 5–10 days [7]
- Serum amylase: Elevated in most cases of parotitis or pancreatitis [8]
- CBC: Usually normal; leukocytosis may occur with meningitis, orchitis, or pancreatitis [8]
- Lipase: If pancreatitis suspected
- CSF analysis (if meningitis suspected): Lymphocytic pleocytosis, normal glucose, normal-to-mildly elevated protein [8]
Critical caveat: Previously immunized patients may not mount a detectable IgM response — RT-PCR or viral culture is required for confirmation in these individuals. [7]
12. Imaging
- Imaging is generally unnecessary for uncomplicated mumps parotitis
- Ultrasound of parotid gland: May help differentiate from abscess, sialolithiasis, or neoplasm if diagnosis is uncertain [10]
- Scrotal ultrasound: If orchitis is suspected and exam is equivocal, or to rule out testicular torsion
- CT head/MRI brain: Only if encephalitis is suspected (altered mental status, seizures, focal deficits)
- CT abdomen: If pancreatitis is suspected and clinical picture is unclear
13. Special Tests
- Buccal swab RT-PCR: Gold standard for diagnosis; coordinate with local/state public health laboratory [7][18-19]
- Viral culture: Available through public health labs and CDC; less sensitive than RT-PCR [8]
- Genotyping (SH gene sequencing): For molecular epidemiology and outbreak linkage, performed at public health labs [18]
- Lumbar puncture: Indicated if meningitis/encephalitis suspected; mumps RT-PCR can be performed on CSF [7-8]
- EEG: To differentiate meningitis from encephalitis if CNS involvement is present [8]
14. ECG
- Myocarditis is a rare complication of mumps; ECG is not routinely indicated
- Obtain ECG if chest pain, dyspnea, tachycardia, or signs of heart failure develop
- Look for: ST-segment changes, T-wave inversions, arrhythmias, low voltage (suggestive of myocarditis)
15. Assessment
- Typical presentation: Prodrome of fever, malaise, myalgias → unilateral or bilateral nonsuppurative parotitis lasting ≥2 days, with pain exacerbated by chewing [1][3][8]
- Atypical presentations: Mumps without parotitis (up to 50% of meningitis cases lack parotid swelling); isolated orchitis, pancreatitis, or meningitis as presenting complaint [1][8]
- Severity stratification:
- Mild: Parotitis only, well-appearing, tolerating PO
- Moderate: Orchitis, significant pain, dehydration
- Severe: Meningitis, encephalitis, pancreatitis, hearing loss
- Complications are more common in adults than children and in males than females [1][11-12]
- Vaccinated patients tend to have milder disease and fewer complications [11][20]
16. Treatment Plan
- Supportive care is the mainstay — no specific antiviral therapy: [2]
- Analgesics/antipyretics (acetaminophen, ibuprofen)
- Warm or cold compresses to parotid glands
- Soft diet, adequate hydration
- Orchitis management: Bed rest, scrotal support, ice packs, NSAIDs; consider short course of corticosteroids for severe cases (limited evidence)
- Meningitis: Supportive; typically self-limited (resolves in 7–10 days) [8]
- Pancreatitis: IV fluids, NPO, pain management
- Isolation: Standard and droplet precautions for 5 days after parotitis onset (CDC, AAP, HICPAC consensus) [21-22]
- Reporting: Mumps is a reportable disease in most U.S. states — notify local/state health department immediately [2]
- Outbreak response: Consider a third dose of MMR vaccine for persons at increased risk during an outbreak, in coordination with public health [4-5]
17. Disposition
- Discharge criteria (majority of cases):
- Uncomplicated parotitis with adequate PO intake
- Pain controlled with oral analgesics
- Reliable follow-up and understanding of isolation precautions
- Admission criteria:
- Meningitis or encephalitis (altered mental status, seizures, focal deficits)
- Severe orchitis with intractable pain or vomiting
- Pancreatitis requiring IV fluids/NPO
- Severe dehydration or inability to tolerate PO
- Immunocompromised host with complications
- Specialist consultation triggers:
- Infectious disease: Outbreak management, atypical presentations
- Urology: Severe or bilateral orchitis
- Neurology: Encephalitis, hearing loss
- ENT: Diagnostic uncertainty regarding parotid mass
18. Follow Up / Return Precautions
- Isolation: Exclude from work, school, or daycare for 5 days after parotitis onset [21-22]
- Follow-up: Primary care within 1–2 weeks; sooner if symptoms worsen
- Return precautions — seek immediate care for:
- Severe headache, neck stiffness, or altered mental status (meningitis/encephalitis)
- Testicular pain or swelling (orchitis)
- Severe abdominal pain (pancreatitis)
- Hearing changes
- High fever (>39.5°C) or inability to tolerate fluids
- Expected course: Parotid swelling typically resolves within 7–10 days; contralateral parotitis may develop within a week of initial onset [23]
- Patient counseling: Mumps is contagious from 2 days before through 5 days after parotitis onset; avoid sharing utensils, drinks, and close contact during this period [4]
- Contacts: Unvaccinated or incompletely vaccinated contacts should receive MMR vaccine; exposed individuals should be monitored for symptoms for 25 days after last exposure [1]
References
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